journalctl
: Query the systemd
Journalupdate-alternatives
: Managing Multiple Versions of Commands and Filesudev
Covers system administration tasks like maintaining, monitoring and customizing an initially installed system.
journalctl
: Query the systemd
Journalupdate-alternatives
: Managing Multiple Versions of Commands and Filesudev
/dev
Directoryuevents
and udev
udev
Daemonudev
Rulesudev
wicked
architecturefirewalld
Zones in NetworkManagersystemd
Target Unitsulimit
: Setting Resources for the User/proc
File System/sys
File Systemrpm -q -i wget
java
Command/var/run/netconfig/resolv.conf
/etc/hosts
/etc/networks
/etc/host.conf
/etc/nsswitch.conf
lpd
udev
Rulesulimit
: Settings in ~/.bashrc
rpcclient
to Request a Windows Server 2012 Share Snapshothostinfo
When Logging In as root
Copyright © 2006– 2022 SUSE LLC and contributors. All rights reserved.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or (at your option) version 1.3; with the Invariant Section being this copyright notice and license. A copy of the license version 1.2 is included in the section entitled “GNU Free Documentation License”.
For SUSE trademarks, see https://www.suse.com/company/legal/. All other third-party trademarks are the property of their respective owners. Trademark symbols (®, ™ etc.) denote trademarks of SUSE and its affiliates. Asterisks (*) denote third-party trademarks.
All information found in this book has been compiled with utmost attention to detail. However, this does not guarantee complete accuracy. Neither SUSE LLC, its affiliates, the authors nor the translators shall be held liable for possible errors or the consequences thereof.
This guide is intended for use by professional network and system administrators during the operation of SUSE® Linux Enterprise. As such, it is solely concerned with ensuring that SUSE Linux Enterprise is properly configured and that the required services on the network are available to allow it to function properly as initially installed. This guide does not cover the process of ensuring that SUSE Linux Enterprise offers proper compatibility with your enterprise's application software or that its core functionality meets those requirements. It assumes that a full requirements audit has been done and the installation has been requested, or that a test installation for such an audit has been requested.
This guide contains the following:
SUSE Linux Enterprise offers a wide range of tools to customize various aspects of the system. This part introduces a few of them.
Learn more about the underlying operating system by studying this part. SUSE Linux Enterprise supports several hardware architectures and you can use this to adapt your own applications to run on SUSE Linux Enterprise. The boot loader and boot procedure information assists you in understanding how your Linux system works and how your own custom scripts and applications may blend in with it.
SUSE Linux Enterprise is designed to be a network operating system. SUSE® Linux Enterprise Desktop includes client support for many network services. It integrates well into heterogeneous environments including MS Windows clients and servers.
Laptops, and the communication between mobile devices like PDAs, or cellular phones and SUSE Linux Enterprise need some special attention. Take care for power conservation and for the integration of different devices into a changing network environment. Also get in touch with the background technologies that provide the needed functionality.
Provides an overview of finding help and additional documentation when you need more information or want to perform specific tasks. There is also a list of the most frequent problems with explanations of how to fix them.
Documentation for our products is available at https://documentation.suse.com/, where you can also find the latest updates, and browse or download the documentation in various formats. The latest documentation updates are usually available in the English version of the documentation.
Many commands are described in detail in their manual
pages. You can view manual pages by running the
man
command followed by a specific command name. If the
man
command is not installed on your system, install it
by running zypper install man
.
The following documentation is available for this product:
This Quick Start guides you step-by-step through the installation of SUSE® Linux Enterprise Desktop 15 SP1.
This guide details how to install single or multiple systems, and how to exploit the product-inherent capabilities for a deployment infrastructure. Choose from various approaches: local installation from physical installation media, customizing the standard installation images, network installation server, mass deployment using a remote-controlled, highly-customized, automated installation process, and initial system configuration.
Covers system administration tasks like maintaining, monitoring and customizing an initially installed system.
Introduces basic concepts of system security, covering both local and network security aspects. Shows how to use the product inherent security software like AppArmor, SELinux, or the auditing system that reliably collects information about any security-relevant events. Supports the administrator with security-related choices and decisions in installing and setting up a secure SUSE Linux Enterprise Server and additional processes to further secure and harden that installation.
An administrator's guide for problem detection, resolution and optimization. Find how to inspect and optimize your system by means of monitoring tools and how to efficiently manage resources. Also contains an overview of common problems and solutions and of additional help and documentation resources.
Introduces the GNOME desktop of SUSE Linux Enterprise Desktop. It guides you through using and configuring the desktop and helps you perform key tasks. It is intended mainly for end users who want to make efficient use of GNOME as their default desktop.
The release notes for this product are available at https://www.suse.com/releasenotes/.
Your feedback and contributions to this documentation are welcome. The following channels for giving feedback are available:
For services and support options available for your product, see https://www.suse.com/support/.
To open a service request, you need a SUSE subscription registered at SUSE Customer Center. Go to https://scc.suse.com/support/requests, log in, and click .
Report issues with the documentation at https://bugzilla.suse.com/. To simplify this process, you can use the links next to headlines in the HTML version of this document. These preselect the right product and category in Bugzilla and add a link to the current section. You can start typing your bug report right away. A Bugzilla account is required.
To contribute to this documentation, use the
links next to headlines in the HTML version of this document. They take you to the source code on GitHub, where you can open a pull request. A GitHub account is required.The
links are only available for the English version of each document. For all other languages, use the links instead.For more information about the documentation environment used for this documentation, see the repository's README at https://github.com/SUSE/doc-sle/blob/main/README.adoc
You can also report errors and send feedback concerning the documentation to <doc-team@suse.com>. Include the document title, the product version, and the publication date of the document. Additionally, include the relevant section number and title (or provide the URL) and provide a concise description of the problem.
The following notices and typographical conventions are used in this documentation:
/etc/passwd
: directory names and file names
PLACEHOLDER: replace PLACEHOLDER with the actual value
PATH
: the environment variable PATH
ls
, --help
: commands, options, and
parameters
user
: users or groups
package name : name of a package
Alt, Alt–F1: a key to press or a key combination; keys are shown in uppercase as on a keyboard
, › : menu items, buttons
Dancing Penguins (Chapter Penguins, ↑Another Manual): This is a reference to a chapter in another manual.
Commands that must be run with root
privileges. Often you can also
prefix these commands with the sudo
command to run them
as non-privileged user.
root #
command
tux >
sudo
command
Commands that can be run by non-privileged users.
tux >
command
Notices
Vital information you must be aware of before proceeding. Warns you about security issues, potential loss of data, damage to hardware, or physical hazards.
Important information you should be aware of before proceeding.
Additional information, for example about differences in software versions.
Helpful information, like a guideline or a piece of practical advice.
SUSE products are supported for up to 13 years. To check the life cycle dates for your product, see https://www.suse.com/lifecycle/.
For SUSE Linux Enterprise, the following life cycles and release cycles apply:
SUSE Linux Enterprise Server has a 13-year life cycle: 10 years of general support and three years of extended support.
SUSE Linux Enterprise Desktop has a 10-year life cycle: seven years of general support and three years of extended support.
Major releases are published every four years. Service packs are published every 12-14 months.
SUSE supports previous SUSE Linux Enterprise service packs for six months after the release of a new service pack.
For some products, Long Term Service Pack Support (LTSS) is available. Find information about our support policy and options at https://www.suse.com/support/policy.html and https://www.suse.com/support/programs/long-term-service-pack-support.html.
Modules have a different life cycle, update policy, and update timeline than their base products. Modules contain software packages and are fully supported parts of SUSE Linux Enterprise Desktop. For more information, see the Article “Modules and Extensions Quick Start”.
To receive support, you need an appropriate subscription with SUSE. To view the specific support offerings available to you, go to https://www.suse.com/support/ and select your product.
The support levels are defined as follows:
Problem determination, which means technical support designed to provide compatibility information, usage support, ongoing maintenance, information gathering and basic troubleshooting using available documentation.
Problem isolation, which means technical support designed to analyze data, reproduce customer problems, isolate problem area and provide a resolution for problems not resolved by Level 1 or prepare for Level 3.
Problem resolution, which means technical support designed to resolve problems by engaging engineering to resolve product defects which have been identified by Level 2 Support.
For contracted customers and partners, SUSE Linux Enterprise Desktop is delivered with L3 support for all packages, except for the following:
Technology Previews
Sound, graphics, fonts and artwork.
Packages that require an additional customer contract.
Some packages shipped as part of the module Workstation Extension are L2-supported only.
Packages with names ending in -devel (containing header files and similar developer resources) will only be supported together with their main packages.
SUSE will only support the usage of original packages. That is, packages that are unchanged and not recompiled.
Technology previews are packages, stacks, or features delivered by SUSE to provide glimpses into upcoming innovations. The previews are included for your convenience to give you the chance to test new technologies within your environment. We would appreciate your feedback! If you test a technology preview, please contact your SUSE representative and let them know about your experience and use cases. Your input is helpful for future development.
However, technology previews come with the following limitations:
Technology previews are still in development. Therefore, they may be functionally incomplete, unstable, or in other ways not suitable for production use.
Technology previews are not supported.
Technology previews may only be available for specific hardware architectures.
Details and functionality of technology previews are subject to change. As a result, upgrading to subsequent releases of a technology preview may be impossible and require a fresh installation.
Technology previews can be dropped at any time. For example, if SUSE discovers that a preview does not meet the customer or market needs, or does not prove to comply with enterprise standards. SUSE does not commit to providing a supported version of such technologies in the future.
For an overview of technology previews shipped with your product, see the release notes at https://www.suse.com/releasenotes/.
Today, many people use computers with a graphical user interface (GUI) like GNOME. Although GUIs offer many features, they're limited when performing automated task execution. Shells complement GUIs well, and this chapter gives an overview of some aspects of shells, in this case the Bash shell.
Many commands and system utilities need to be run as root to modify files and/or perform tasks that only the super user is allowed to. For security reasons and to avoid accidentally running dangerous commands, it is generally advisable not to log in directly as root. Instead, it is recommended to wo…
SUSE offers a continuous stream of software security updates for your product. By default, the update applet is used to keep your system up-to-date. Refer to Book “Deployment Guide”, Chapter 16 “Installing or Removing Software”, Section 16.5 “The GNOME Package Updater” for further information on the…
YaST is the installation and configuration tool for SUSE Linux Enterprise Desktop. It has a graphical interface and the capability to customize your system quickly during and after the installation. It can be used to set up hardware, configure the network, system services, and tune your security set…
This section is intended for system administrators and experts who do not run an X server on their systems and depend on the text-based installation tool. It provides basic information about starting and operating YaST in text mode.
This chapter describes Zypper and RPM, two command line tools for managing
software. For a definition of the terminology used in this context (for
example, repository
, patch
, or
update
) refer to
Book “Deployment Guide”, Chapter 16 “Installing or Removing Software”, Section 16.1 “Definition of Terms”.
Snapper allows creating and managing file system snapshots. File system snapshots allow keeping a copy of the state of a file system at a certain point of time. The standard setup of Snapper is designed to allow rolling back system changes. However, you can also use it to create on-disk backups of user data. As the basis for this functionality, Snapper uses the Btrfs file system or thinly-provisioned LVM volumes with an XFS or Ext4 file system.
This document describes the basic principles of the Kernel Live Patching (KLP) technology, and provides usage guidelines for the SLE Live Patching service.
Transactional updates are available in SUSE Linux Enterprise Desktop as a technology preview, for updating SLES when the root filesystem is read-only. Transactional updates are atomic (all updates are applied only if all updates succeed) and support rollbacks. It does not affect a running system as no changes are activated until after the system is rebooted. As reboots are disruptive, the admin must decide if a reboot is more expensive than disturbing running services. If reboots are too expensive then do not use transactional updates.
Transactional updates are run daily by the
transactional-update
script. The script checks for
available updates. If there are any updates, it creates a new snapshot of
the root file system in the background, and then fetches updates from the
release channels. After the new snapshot is completely updated, it is
marked as active and will be the new default root file system after the next
reboot of the system. When transactional-update
is set to run
automatically (which is the default behavior) it also reboots the system.
Both the time that the update runs and the reboot maintenance window are
configurable.
Only packages that are part of the snapshot of the root file system can be updated. If packages contain files that are not part of the snapshot, the update could fail or break the system.
RPMs that require a license to be accepted cannot be updated.
Virtual Network Computing (VNC) enables you to access a remote computer via a graphical desktop, and run remote graphical applications. VNC is platform-independent and accesses the remote machine from any operating system. This chapter describes how to connect to a VNC server with the desktop clients vncviewer and Remmina, and how to operate a VNC server.
SUSE Linux Enterprise Desktop supports two different kinds of VNC sessions: One-time sessions that “live” as long as the VNC connection from the client is kept up, and persistent sessions that “live” until they are explicitly terminated.
A VNC server can offer both kinds of sessions simultaneously on different ports, but an open session cannot be converted from one type to the other.
Today, a typical user has several computers: home and workplace machines, a laptop, a smartphone or a tablet. This makes the task of keeping files and documents in synchronization across multiple devices all the more important.
Today, many people use computers with a graphical user interface (GUI) like GNOME. Although GUIs offer many features, they're limited when performing automated task execution. Shells complement GUIs well, and this chapter gives an overview of some aspects of shells, in this case the Bash shell.
Traditionally, the Linux shell is Bash (Bourne again Shell). When this chapter speaks about “the shell” it means Bash. There are more shells available (ash, csh, ksh, zsh, …), each employing different features and characteristics. If you need further information about other shells, search for shell in YaST.
A shell can be invoked as an:
Interactive login shell.
This is used when logging in to a machine, invoking Bash with the
--login
option or when logging in to a remote machine
with SSH.
“Ordinary” interactive shell. This is normally the case when starting xterm, konsole, gnome-terminal, or similar command-line interface (CLI) tools.
Non-interactive shell. This is invoked when invoking a shell script at the command line.
Depending on the type of shell you use, different configuration files will be read. The following tables show the login and non-login shell configuration files.
File |
Description |
---|---|
|
Do not modify this file, otherwise your modifications may be destroyed during your next update! |
|
Use this file if you extend |
|
Contains system-wide configuration files for specific programs |
|
Insert user specific configuration for login shells here |
Note that the login shell also sources the configuration files listed under Table 1.2, “Bash Configuration Files for Non-Login Shells”.
|
Do not modify this file, otherwise your modifications may be destroyed during your next update! |
|
Use this file to insert your system-wide modifications for Bash only |
|
Insert user specific configuration here |
Additionally, Bash uses some more files:
File |
Description |
---|---|
|
Contains a list of all commands you have typed |
|
Executed when logging out |
|
User defined aliases of frequently used commands. See
|
There are special shells that block users from logging into
the system: /bin/false
and
/sbin/nologin
. Both fail silently
when the user attempts to log into the system. This was intended
as a security measure for system users, though modern
Linux operating systems have more effective tools for controlling system
access, such as PAM and AppArmor.
The default on SUSE Linux Enterprise Desktop is to assign /bin/bash
to human users, and /bin/false
or
/sbin/nologin
to system users.
The nobody
user has /bin/bash
for historical reasons, as
it is a minimally-privileged user that used to be the default for system users.
However, whatever little bit of security gained by using
nobody
is lost when
multiple system users use it. It should be possible to change it to
/sbin/nologin
; the fastest way to test it is change
it and see if it breaks any services or applications.
Use the following command to list which shells are assigned to all users,
system and human users, in /etc/passwd
. The output
varies according to the services and users on your system:
tux >
sort -t: -k 7 /etc/passwd | awk -F: '{print $1"\t" $7}' | column -t
tux /bin/bash
nobody /bin/bash
root /bin/bash
avahi /bin/false
chrony /bin/false
dhcpd /bin/false
dnsmasq /bin/false
ftpsecure /bin/false
lightdm /bin/false
mysql /bin/false
postfix /bin/false
rtkit /bin/false
sshd /bin/false
tftp /bin/false
unbound /bin/false
bin /sbin/nologin
daemon /sbin/nologin
ftp /sbin/nologin
lp /sbin/nologin
mail /sbin/nologin
man /sbin/nologin
nscd /sbin/nologin
polkitd /sbin/nologin
pulse /sbin/nologin
qemu /sbin/nologin
radvd /sbin/nologin
rpc /sbin/nologin
statd /sbin/nologin
svn /sbin/nologin
systemd-coredump /sbin/nologin
systemd-network /sbin/nologin
systemd-timesync /sbin/nologin
usbmux /sbin/nologin
vnc /sbin/nologin
wwwrun /sbin/nologin
messagebus /usr/bin/false
scard /usr/sbin/nologin
The following table provides a short overview of the most important higher-level directories that you find on a Linux system. Find more detailed information about the directories and important subdirectories in the following list.
Directory |
Contents |
---|---|
|
Root directory—the starting point of the directory tree. |
|
Essential binary files, such as commands that are needed by both the system administrator and normal users. Usually also contains the shells, such as Bash. |
|
Static files of the boot loader. |
|
Files needed to access host-specific devices. |
|
Host-specific system configuration files. |
|
Holds the home directories of all users who have accounts on the system.
However, |
|
Essential shared libraries and kernel modules. |
|
Mount points for removable media. |
|
Mount point for temporarily mounting a file system. |
|
Add-on application software packages. |
|
Home directory for the superuser |
|
Essential system binaries. |
|
Data for services provided by the system. |
|
Temporary files. |
|
Secondary hierarchy with read-only data. |
|
Variable data such as log files. |
|
Only available if you have both Microsoft Windows* and Linux installed on your system. Contains the Windows data. |
The following list provides more detailed information and gives some examples of which files and subdirectories can be found in the directories:
/bin
Contains the basic shell commands that may be used both by root
and
by other users. These commands include ls
,
mkdir
, cp
, mv
,
rm
and rmdir
.
/bin
also contains Bash, the default shell in
SUSE Linux Enterprise Desktop.
/boot
Contains data required for booting, such as the boot loader, the kernel, and other data that is used before the kernel begins executing user-mode programs.
/dev
Holds device files that represent hardware components.
/etc
Contains local configuration files that control the operation of programs
like the X Window System. The /etc/init.d
subdirectory contains LSB init scripts that can be executed during the
boot process.
/home/USERNAME
Holds the private data of every user who has an account on the system. The
files located here can only be modified by their owner or by the system
administrator. By default, your e-mail directory and personal desktop
configuration are located here in the form of hidden files and
directories, such as .gconf/
and
.config
.
If you are working in a network environment, your home directory may be
mapped to a directory in the file system other than
/home
.
/lib
Contains the essential shared libraries needed to boot the system and to run the commands in the root file system. The Windows equivalent for shared libraries are DLL files.
/media
Contains mount points for removable media, such as CD-ROMs, flash disks,
and digital cameras (if they use USB). /media
generally holds any type of drive except the hard disk of your system.
When your removable medium has been inserted or connected to the system
and has been mounted, you can access it from here.
/mnt
This directory provides a mount point for a temporarily mounted file
system. root
may mount file systems here.
/opt
Reserved for the installation of third-party software. Optional software and larger add-on program packages can be found here.
/root
Home directory for the root
user. The personal data of root
is
located here.
/run
A tmpfs directory used by systemd
and various
components. /var/run
is a symbolic link to
/run
.
/sbin
As the s
indicates, this directory holds utilities for
the superuser. /sbin
contains the binaries essential
for booting, restoring and recovering the system in addition to the
binaries in /bin
.
/srv
Holds data for services provided by the system, such as FTP and HTTP.
/tmp
This directory is used by programs that require temporary storage of files.
/tmp
at Boot Time
Data stored in /tmp
is not guaranteed to survive a
system reboot. It depends, for example, on settings made in
/etc/tmpfiles.d/tmp.conf
.
/usr
/usr
has nothing to do with users, but is the acronym
for Unix system resources. The data in /usr
is
static, read-only data that can be shared among various hosts compliant
with the Filesystem Hierarchy Standard
(FHS). This
directory contains all application programs including the graphical
desktops such as GNOME and establishes a secondary hierarchy in the file
system. /usr
holds several subdirectories, such as
/usr/bin
, /usr/sbin
,
/usr/local
, and /usr/share/doc
.
/usr/bin
Contains generally accessible programs.
/usr/sbin
Contains programs reserved for the system administrator, such as repair functions.
/usr/local
In this directory the system administrator can install local, distribution-independent extensions.
/usr/share/doc
Holds various documentation files and the release notes for your system.
In the manual
subdirectory find an online version of
this manual. If more than one language is installed, this directory may
contain versions of the manuals for different languages.
Under packages
find the documentation included in the
software packages installed on your system. For every package, a
subdirectory
/usr/share/doc/packages/PACKAGENAME
is created that often holds README files for the package and sometimes
examples, configuration files or additional scripts.
If HOWTOs are installed on your system /usr/share/doc
also holds the howto
subdirectory in which to find
additional documentation on many tasks related to the setup and operation
of Linux software.
/var
Whereas /usr
holds static, read-only data,
/var
is for data which is written during system
operation and thus is variable data, such as log files or spooling data.
For an overview of the most important log files you can find under
/var/log/
, refer to
Table 37.1, “Log Files”.
/windows
Only available if you have both Microsoft Windows and Linux installed on your system. Contains the Windows data available on the Windows partition of your system. Whether you can edit the data in this directory depends on the file system your Windows partition uses. If it is FAT32, you can open and edit the files in this directory. For NTFS, SUSE Linux Enterprise Desktop also includes write access support. However, the driver for the NTFS-3g file system has limited functionality.
Shell scripts provide a convenient way to perform a wide range of tasks: collecting data, searching for a word or phrase in a text and other useful things. The following example shows a small shell script that prints a text:
#!/bin/sh 1 # Output the following line: 2 echo "Hello World" 3
The first line begins with the Shebang
characters ( | |
The second line is a comment beginning with the hash sign. We recommend that you comment difficult lines. With proper commenting, you can remember the purpose and function of the line. Also, other readers will hopefully understand your script. Commenting is considered good practice in the development community. | |
The third line uses the built-in command |
Before you can run this script, there are a few prerequisites:
Every script should contain a Shebang line (as in the example above). If the line is missing, you need to call the interpreter manually.
You can save the script wherever you want. However, it is a good idea to
save it in a directory where the shell can find it. The search path in a
shell is determined by the environment variable PATH
.
Usually a normal user does not have write access to
/usr/bin
. Therefore it is recommended to save your
scripts in the users' directory ~/bin/
. The above
example gets the name hello.sh
.
The script needs executable permissions. Set the permissions with the following command:
tux >
chmod +x ~/bin/hello.sh
If you have fulfilled all of the above prerequisites, you can execute the script in the following ways:
As Absolute Path.
The script can be executed with an absolute path. In our case, it is
~/bin/hello.sh
.
Everywhere.
If the PATH
environment variable contains the directory
where the script is located, you can execute the script with
hello.sh
.
Each command can use three channels, either for input or output:
Standard Output. This is the default output channel. Whenever a command prints something, it uses the standard output channel.
Standard Input. If a command needs input from users or other commands, it uses this channel.
Standard Error. Commands use this channel for error reporting.
To redirect these channels, there are the following possibilities:
Command > File
Saves the output of the command into a file, an existing file will be
deleted. For example, the ls
command writes its output
into the file listing.txt
:
tux >
ls > listing.txt
Command >> File
Appends the output of the command to a file. For example, the
ls
command appends its output to the file
listing.txt
:
tux >
ls >> listing.txt
Command < File
Reads the file as input for the given command. For example, the
read
command reads in the content of the file into the
variable:
tux >
read a < foo
Command1 | Command2
Redirects the output of the left command as input for the right command.
For example, the cat
command outputs the content of
the /proc/cpuinfo
file. This output is used by
grep
to filter only those lines which contain
cpu
:
tux >
cat /proc/cpuinfo | grep cpu
Every channel has a file descriptor: 0 (zero) for
standard input, 1 for standard output and 2 for standard error. It is
allowed to insert this file descriptor before a <
or
>
character. For example, the following line searches
for a file starting with foo
, but suppresses its errors
by redirecting it to /dev/null
:
tux >
find / -name "foo*" 2>/dev/null
An alias is a shortcut definition of one or more commands. The syntax for an alias is:
alias NAME=DEFINITION
For example, the following line defines an alias lt
that
outputs a long listing (option -l
), sorts it by
modification time (-t
), and prints it in reverse sorted order (-r
):
tux >
alias lt='ls -ltr'
To view all alias definitions, use alias
. Remove your
alias with unalias
and the corresponding alias name.
A shell variable can be global or local. Global variables, or environment variables, can be accessed in all shells. In contrast, local variables are visible in the current shell only.
To view all environment variables, use the printenv
command. If you need to know the value of a variable, insert the name of
your variable as an argument:
tux >
printenv PATH
A variable, be it global or local, can also be viewed with
echo
:
tux >
echo $PATH
To set a local variable, use a variable name followed by the equal sign, followed by the value:
tux >
PROJECT="SLED"
Do not insert spaces around the equal sign, otherwise you get an error. To
set an environment variable, use export
:
tux >
export NAME="tux"
To remove a variable, use unset
:
tux >
unset NAME
The following table contains some common environment variables which can be used in you shell scripts:
|
the home directory of the current user |
|
the current host name |
|
when a tool is localized, it uses the language from this environment
variable. English can also be set to |
|
the search path of the shell, a list of directories separated by colon |
|
specifies the normal prompt printed before each command |
|
specifies the secondary prompt printed when you execute a multi-line command |
|
current working directory |
|
the current user |
For example, if you have the script foo.sh
you can
execute it like this:
tux >
foo.sh "Tux Penguin" 2000
To access all the arguments which are passed to your script, you need
positional parameters. These are $1
for the first argument,
$2
for the second, and so on. You can have up to nine
parameters. To get the script name, use $0
.
The following script foo.sh
prints all arguments from 1
to 4:
#!/bin/sh echo \"$1\" \"$2\" \"$3\" \"$4\"
If you execute this script with the above arguments, you get:
"Tux Penguin" "2000" "" ""
Variable substitutions apply a pattern to the content of a variable either from the left or right side. The following list contains the possible syntax forms:
${VAR#pattern}
removes the shortest possible match from the left:
tux >
file=/home/tux/book/book.tar.bz2tux >
echo ${file#*/} home/tux/book/book.tar.bz2
${VAR##pattern}
removes the longest possible match from the left:
tux >
file=/home/tux/book/book.tar.bz2tux >
echo ${file##*/} book.tar.bz2
${VAR%pattern}
removes the shortest possible match from the right:
tux >
file=/home/tux/book/book.tar.bz2tux >
echo ${file%.*} /home/tux/book/book.tar
${VAR%%pattern}
removes the longest possible match from the right:
tux >
file=/home/tux/book/book.tar.bz2tux >
echo ${file%%.*} /home/tux/book/book
${VAR/pattern_1/pattern_2}
substitutes the content of VAR from the PATTERN_1 with PATTERN_2:
tux >
file=/home/tux/book/book.tar.bz2tux >
echo ${file/tux/wilber} /home/wilber/book/book.tar.bz2
Shells allow you to concatenate and group commands for conditional execution. Each command returns an exit code which determines the success or failure of its operation. If it is 0 (zero) the command was successful, everything else marks an error which is specific to the command.
The following list shows, how commands can be grouped:
Command1 ; Command2
executes the commands in sequential order. The exit code is not checked.
The following line displays the content of the file with
cat
and then prints its file properties with
ls
regardless of their exit codes:
tux >
cat filelist.txt ; ls -l filelist.txt
Command1 && Command2
runs the right command, if the left command was successful (logical AND). The following line displays the content of the file and prints its file properties only, when the previous command was successful (compare it with the previous entry in this list):
tux >
cat filelist.txt && ls -l filelist.txt
Command1 || Command2
runs the right command, when the left command has failed (logical OR).
The following line creates only a directory in
/home/wilber/bar
when the creation of the directory
in /home/tux/foo
has failed:
tux >
mkdir /home/tux/foo || mkdir /home/wilber/bar
funcname(){ ... }
creates a shell function. You can use the positional parameters to access
its arguments. The following line defines the function
hello
to print a short message:
tux >
hello() { echo "Hello $1"; }
You can call this function like this:
tux >
hello Tux
which prints:
Hello Tux
To control the flow of your script, a shell has while
,
if
, for
and case
constructs.
The if
command is used to check expressions. For
example, the following code tests whether the current user is Tux:
if test $USER = "tux"; then echo "Hello Tux." else echo "You are not Tux." fi
The test expression can be as complex or simple as possible. The following
expression checks if the file foo.txt
exists:
if test -e /tmp/foo.txt ; then echo "Found foo.txt" fi
The test expression can also be abbreviated in square brackets:
if [ -e /tmp/foo.txt ] ; then echo "Found foo.txt" fi
Find more useful expressions at https://bash.cyberciti.biz/guide/If..else..fi.
for
Command #Edit source
The for
loop allows you to execute commands to a list of
entries. For example, the following code prints some information about PNG
files in the current directory:
for i in *.png; do ls -l $i done
Important information about Bash is provided in the man pages man
bash
. More about this topic can be found in the following list:
http://tldp.org/LDP/Bash-Beginners-Guide/html/index.html—Bash Guide for Beginners
http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO.html—BASH Programming - Introduction HOW-TO
http://tldp.org/LDP/abs/html/index.html—Advanced Bash-Scripting Guide
http://www.grymoire.com/Unix/Sh.html—Sh - the Bourne Shell
Many commands and system utilities need to be run as root
to modify
files and/or perform tasks that only the super user is allowed to. For
security reasons and to avoid accidentally running dangerous commands, it is
generally advisable not to log in directly as root
. Instead, it is
recommended to work as a normal, unprivileged user and use the sudo
command to run commands with elevated privileges.
On SUSE Linux Enterprise Desktop, sudo
is configured by default to work similarly to su.
However, sudo
offers the possibility to allow users to run commands with
privileges of any other user in a highly configurable manner. This can be
used to assign roles with specific privileges to certain users and groups. It
is for example possible to allow members of the group users
to run a
command with the privileges of wilber
. Access to the command can be
further restricted by, for example, forbidding to specify any command
options. While su always requires the root
password for authentication
with PAM, sudo
can be configured to authenticate with your own credentials.
This increases security by not having to share the root
password. For
example, you can allow members of the group users
to run a command
frobnicate
as wilber
, with the restriction that
no arguments are specified. This can be used to assign roles with specific
abilities to certain users and groups.
sudo
Usage #Edit source
sudo
is simple to use, yet very powerful.
Logged in as normal user, you can run any command as root
by
adding sudo
before it. It will prompt for the root password and, if
authenticated successfully, run the command as root
:
tux >
id -un
1 tuxtux >
sudo
id -un
root's password:2 roottux >
id -un
tux3tux >
sudo
id -un
4 root
The | |
The password is not shown during input, neither as clear text nor as bullets. | |
Only commands started with | |
For a limited amount of time, you do not need to enter the |
I/O redirection does not work as you would probably expect:
tux >
sudo
echo s > /proc/sysrq-trigger bash: /proc/sysrq-trigger: Permission deniedtux >
sudo
cat < /proc/1/maps bash: /proc/1/maps: Permission denied
Only the echo
/cat
binary is run with
elevated privileges, while the redirection is performed by the user's
shell with user privileges. You can either start a shell like in
Section 2.1.2, “Starting a Shell” or use the dd
utility
instead:
echo s | sudo dd of=/proc/sysrq-trigger sudo dd if=/proc/1/maps | cat
Having to add sudo
before every command can be cumbersome. While you
could specify a shell as a command sudo bash
, it is
recommended to rather use one of the built-in mechanisms to start a shell:
sudo -s (<command>)
Starts a shell specified by the SHELL
environment
variable or the target user's default shell. If a command is given, it
is passed to the shell (with the -c
option), else the
shell is run in interactive mode.
tux:~ >
sudo -i root's password:root:/home/tux #
exittux:~ >
sudo -i (<command>)
Like -s
, but starts the shell as login shell. This
means that the shell's start-up files (.profile
etc.) are processed and the current working directory is set to the
target user's home directory.
tux:~ >
sudo -i root's password:root:~ #
exittux:~ >
By default, sudo
does not propagate environment variables:
tux >
ENVVAR=test env | grep ENVVAR ENVVAR=testtux >
ENVVAR=test sudo env | grep ENVVAR root's password: 1tux >
The empty output shows that the environment variable
|
This behavior can be changed by the env_reset
option,
see Table 2.1, “Useful Flags and Options”.
sudo
#Edit source
sudo
is a very flexible tool with extensive configuration.
If you accidentally locked yourself out of sudo
, use su
-
and the root
password to get a root shell.
To fix the error, run visudo
.
The main policy configuration file for sudo
is
/etc/sudoers
. As it is possible to lock yourself out
of the system because of errors in this file, it is strongly
recommended to use visudo
for editing. It will prevent
simultaneous changes to the opened file and check for syntax errors before
saving the modifications.
Despite its name, you can also use editors other than vi by setting the
EDITOR
environment variable, for example:
sudo EDITOR=/usr/bin/nano visudo
However, the /etc/sudoers
file itself is supplied by
the system packages and modifications may break on updates. Therefore, it
is recommended to put custom configuration into files in the
/etc/sudoers.d/
directory. Any file in there is
automatically included. To create or edit a file in that subdirectory, run:
sudo visudo -f /etc/sudoers.d/NAME
Alternatively with a different editor (for example
nano
):
sudo EDITOR=/usr/bin/nano visudo -f /etc/sudoers.d/NAME
/etc/sudoers.d
The #includedir
command in
/etc/sudoers
, used for
/etc/sudoers.d
, ignores files that end in
~
(tilde) or contain a .
(dot).
For more information on the visudo
command, run
man 8 visudo
.
In the sudoers configuration files, there are two types of options: strings and flags. While strings can contain any value, flags can be turned either ON or OFF. The most important syntax constructs for sudoers configuration files are:
# Everything on a line after a # gets ignored 1 Defaults !insults # Disable the insults flag 2 Defaults env_keep += "DISPLAY HOME" # Add DISPLAY and HOME to env_keep tux ALL = NOPASSWD: /usr/bin/frobnicate, PASSWD: /usr/bin/journalctl 3
There are two exceptions: | |
Remove the | |
Option name |
Description |
Example |
---|---|---|
targetpw
|
This flag controls whether the invoking user is required to enter the
password of the target user (ON) (for example |
Defaults targetpw # Turn targetpw flag ON |
rootpw
|
If set, |
Defaults !rootpw # Turn rootpw flag OFF |
env_reset
|
If set, |
Defaults env_reset # Turn env_reset flag ON |
env_keep
|
List of environment variables to keep when the
|
# Set env_keep to contain EDITOR and PROMPT Defaults env_keep = "EDITOR PROMPT" Defaults env_keep += "JRE_HOME" # Add JRE_HOME Defaults env_keep -= "JRE_HOME" # Remove JRE_HOME |
env_delete
|
List of environment variables to remove when the
|
# Set env_delete to contain EDITOR and PROMPT Defaults env_delete = "EDITOR PROMPT" Defaults env_delete += "JRE_HOME" # Add JRE_HOME Defaults env_delete -= "JRE_HOME" # Remove JRE_HOME |
The Defaults
token can also be used to create aliases
for a collection of users, hosts, and commands. Furthermore, it is possible
to apply an option only to a specific set of users.
For detailed information about the /etc/sudoers
configuration file, consult man 5 sudoers
.
Rules in the sudoers configuration can be very complex, so this section
will only cover the basics. Each rule follows the basic scheme
([]
marks optional parts):
#Who Where As whom Tag What User_List Host_List = [(User_List)] [NOPASSWD:|PASSWD:] Cmnd_List
User_List
One or more (separated by ,
) identifiers: Either a
user name, a group in the format %GROUPNAME
or a user
ID in the format #UID
. Negation can be performed with
a !
prefix.
Host_List
One or more (separated by ,
) identifiers: Either a
(fully qualified) host name or an IP address. Negation can be performed
with a !
prefix. ALL
is the usual
choice for Host_List
.
NOPASSWD:|PASSWD:
The user will not be prompted for a password when running commands
matching CMDSPEC
after NOPASSWD:
.
PASSWD
is the default, it only needs to be specified
when both are on the same line:
tux ALL = PASSWD: /usr/bin/foo, NOPASSWD: /usr/bin/bar
Cmnd_List
One or more (separated by ,
) specifiers: A path to an
executable, followed by allowed arguments or nothing.
/usr/bin/foo # Anything allowed /usr/bin/foo bar # Only "/usr/bin/foo bar" allowed /usr/bin/foo "" # No arguments allowed
ALL
can be used as User_List
,
Host_List
, and Cmnd_List
.
A rule that allows tux
to run all commands as root without
entering a password:
tux ALL = NOPASSWD: ALL
A rule that allows tux
to run systemctl restart
apache2
:
tux ALL = /usr/bin/systemctl restart apache2
A rule that allows tux
to run wall
as
admin
with no arguments:
tux ALL = (admin) /usr/bin/wall ""
Constructs of the kind
ALL ALL = ALL
must not be used without Defaults
targetpw
, otherwise anyone can run commands as root
.
When specifying the group name in the sudoers
file, make sure that you use the the NetBIOS domain name instead of the realm, for example:
%DOMAIN\\GROUP_NAME ALL = (ALL) ALL
Keep in mind that when using winbindd, the format also depends on the winbind separator
option in the smb.conf
file. By default, it is \
. If it is changed, for example, to +
, then the account format in sudoers
file must be DOMAIN+GROUP_NAME
.
Although the default configuration is often sufficient for simple setups and desktop environments, custom configurations can be very useful.
sudo
without root
Password #Edit source
In cases with special restrictions (“user X can only run command Y as
root
”) it is not possible. In other cases, it is still
favorable to have some kind of separation. By convention, members of the
group wheel
can run all commands
with sudo
as root.
Add yourself to the wheel
group
If your user account is not already member of the
wheel
group, add it by running
sudo usermod -a -G wheel
USERNAME
and logging out and in
again. Verify that the change was successful by running groups
USERNAME
.
Make authentication with the invoking user's password the default.
Create the file /etc/sudoers.d/userpw
with
visudo
(see Section 2.2.1, “Editing the Configuration Files”) and
add:
Defaults !targetpw
Select a new default rule.
Depending on whether you want users to re-enter their passwords,
uncomment the specific line in /etc/sudoers
and
comment out the default rule.
## Uncomment to allow members of group wheel to execute any command # %wheel ALL=(ALL) ALL ## Same thing without a password # %wheel ALL=(ALL) NOPASSWD: ALL
Make the default rule more restrictive
Comment out or remove the allow-everything rule in
/etc/sudoers
:
ALL ALL=(ALL) ALL # WARNING! Only use this together with 'Defaults targetpw'!
Do not forget this step, otherwise any user can
execute any command as root
!
Test the configuration
Try to run sudo
as member and non-member of
wheel
.
tux:~ >
groups users wheeltux:~ >
sudo id -un tux's password: rootwilber:~ >
groups userswilber:~ >
sudo id -un wilber is not in the sudoers file. This incident will be reported.
sudo
with X.Org Applications #Edit source
When starting graphical applications with sudo
, you will encounter the
following error:
tux >
sudo
xterm xterm: Xt error: Can't open display: %s xterm: DISPLAY is not set
YaST will pick the ncurses interface instead of the graphical one.
To use X.Org in applications started with sudo
, the environment
variables DISPLAY
and XAUTHORITY
need to be
propagated. To configure this, create the file
/etc/sudoers.d/xorg
, (see
Section 2.2.1, “Editing the Configuration Files”) and add the following line:
Defaults env_keep += "DISPLAY XAUTHORITY"
If not set already, set the XAUTHORITY
variable as follows:
export XAUTHORITY=~/.Xauthority
Now X.Org applications can be run as usual:
sudo yast2
A quick overview about the available command line switches can be retrieved
by sudo --help
. An explanation and other important
information can be found in the man page: man 8 sudo
,
while the configuration is documented in man 5 sudoers
.
SUSE offers a continuous stream of software security updates for your product. By default, the update applet is used to keep your system up-to-date. Refer to Book “Deployment Guide”, Chapter 16 “Installing or Removing Software”, Section 16.5 “The GNOME Package Updater” for further information on the update applet. This chapter covers the alternative tool for updating software packages: YaST Online Update.
The current patches for SUSE® Linux Enterprise Desktop are available from an update software repository. If you have registered your product during the installation, an update repository is already configured. If you have not registered SUSE Linux Enterprise Desktop, you can do so by starting the in YaST. Alternatively, you can manually add an update repository from a source you trust. To add or remove repositories, start the Repository Manager with › in YaST. Learn more about the Repository Manager in Book “Deployment Guide”, Chapter 16 “Installing or Removing Software”, Section 16.4 “Managing Software Repositories and Services”.
If you are not able to access the update catalog, this might be because of an expired subscription. Normally, SUSE Linux Enterprise Desktop comes with a one-year or three-year subscription, during which you have access to the update catalog. This access will be denied after the subscription ends.
If an access to the update catalog is denied, you will see a warning message prompting you to visit the SUSE Customer Center and check your subscription. The SUSE Customer Center is available at https://scc.suse.com//.
SUSE provides updates with different relevance levels:
Fix severe security hazards and should always be installed.
Fix issues that could compromise your computer.
Fix non-security relevant issues or provide enhancements.
To open the YaST yast2 online_update
.
The
window consists of four sections.
The SUSE Linux Enterprise Desktop. The patches are sorted by security relevance:
security
, recommended
, and
optional
. You can change the view of the
section by selecting one of the following options
from :
Non-installed patches that apply to packages installed on your system.
Patches that either apply to packages not installed on your system, or patches that have requirements which have already have been fulfilled (because the relevant packages have already been updated from another source).
All patches available for SUSE Linux Enterprise Desktop.
Each list entry in the Shift–F1. Actions required by Security
and
Recommended
patches are automatically preset. These
actions are ,
and .
If you install an up-to-date package from a repository other than the update repository, the requirements of a patch for this package may be fulfilled with this installation. In this case a check mark is displayed in front of the patch summary. The patch will be visible in the list until you mark it for installation. This will in fact not install the patch (because the package already is up-to-date), but mark the patch as having been installed.
Select an entry in the
section to view a short at the bottom left corner of the dialog. The upper right section lists the packages included in the selected patch (a patch can consist of several packages). Click an entry in the upper right section to view details about the respective package that is included in the patch.The YaST Online Update dialog allows you to either install all available patches at once or manually select the desired patches. You may also revert patches that have been applied to the system.
By default, all new patches (except optional
ones) that
are currently available for your system are already marked for installation.
They will be applied automatically once you click
or .
If one or multiple patches require a system reboot, you will be notified
about this before the patch installation starts. You can then either decide
to continue with the installation of the selected patches, skip the
installation of all patches that need rebooting and install the rest, or go
back to the manual patch selection.
Start YaST and select
› .
To automatically apply all new patches (except optional
ones) that are currently available for your system, click
or .
First modify the selection of patches that you want to apply:
Use the respective filters and views that the interface provides. For details, refer to Section 3.1, “The Online Update Dialog”.
Select or deselect patches according to your needs and wishes by right-clicking the patch and choosing the respective action from the context menu.
Do not deselect any security
-related patches without
a very good reason. These patches fix severe security hazards and
prevent your system from being exploited.
Most patches include updates for several packages. To change actions for single packages, right-click a package in the package view and choose an action.
To confirm your selection and apply the selected patches, proceed with
or .After the installation is complete, click
to leave the YaST . Your system is now up-to-date.Maintenance updates are carefully tested, to minimize the risk of introducing a bug. If a patch proves to contain a bug, it is automatically retracted. A new update (with a higher version number) is issued to revert the buggy patch, and is blocked from being installed again. You can see retracted patches, and their history, on the
tab.
You may configure automatic updates with a daily, weekly, or
monthly schedule with YaST. Install the
yast2-online-update-configuration
package.
By default, updates are downloaded as delta RPMs. Since rebuilding RPM packages from delta RPMs is a memory- and processor-intensive task, certain setups or hardware configurations might require you to disable the use of delta RPMs for the sake of performance.
Some patches, such as kernel updates or packages requiring license agreements, require user interaction, which would cause the automatic update procedure to stop. You can configure skipping patches that require user interaction.
Use the
tab in the YaST module to review available and installed patches, including references to bug reports and CVE bulletins.After installation, start YaST and select yast2-online-update-configuration is not installed, you will be prompted to do that.
› . Choose › . If the
Alternatively, start the module with
yast2 online_update_configuration
from the command
line.
Choose the update interval:
, , or .Sometimes patches may require the attention of the administrator, for example when restarting critical services. For example, this might be an update for Docker Open Source Engine that requires all containers to be restarted. Before these patches are installed, the user is informed about the consequences and is asked to confirm the installation of the patch. Such patches are called “Interactive Patches”.
When installing patches automatically, it is assumed that you have accepted the installation of interactive patches. If you prefer to review these patches before they get installed, check
. In this case, interactive patches will be skipped during automated patching. Make sure to periodically run a manual online update, to check whether interactive patches are waiting to be installed.To automatically accept any license agreements, activate
.To automatically install all packages recommended by updated packages, activate
.To disable the use of delta RPMs (for performance reasons), un-check
.To filter the patches by category (such as security or recommended), check
and add the appropriate patch categories from the list. Only patches of the selected categories will be installed. It is a good practice to enable only automatic updates, and to manually review all others. Patching is usually reliable, but you may wish to test non-security patches, and roll them back if you encounter any problems.supply patches for package management and YaST features and modules.
patches provide crucial updates and bugfixes.
patches are optional bugfixes and enhancements.
are new packages.
is equivalent to miscellaneous.
is unused.
Confirm your configuration by clicking
.The automatic online update does not automatically restart the system afterward. If there are package updates that require a system reboot, you need to do this manually.
YaST is the installation and configuration tool for SUSE Linux Enterprise Desktop. It has a graphical interface and the capability to customize your system quickly during and after the installation. It can be used to set up hardware, configure the network, system services, and tune your security settings.
YaST has a set of advanced key combinations.
Take and save a screenshot. May not be available when YaST is running under some desktop environments.
Enable/disable the color palette optimized for vision impaired users.
Enable/disable logging of debug messages.
Open a file dialog to save log files to a non-standard location.
Send a DebugEvent. YaST modules can react to this by executing special debugging actions. The result depends on the specific YaST module.
Start/stop macro recorder.
Replay macro.
Show style sheet editor.
Dump widget tree to the log file.
Open a terminal window (xterm). Useful for installation process via VNC.
Show widget tree browser.
This section is intended for system administrators and experts who do not run an X server on their systems and depend on the text-based installation tool. It provides basic information about starting and operating YaST in text mode.
YaST in text mode uses the ncurses library to provide an easy pseudo-graphical user interface. The ncurses library is installed by default. The minimum supported size of the terminal emulator in which to run YaST is 80x25 characters.
When you start YaST in text mode, the YaST control center appears (see Figure 5.1). The main window consists of three areas. The left frame features the categories to which the various modules belong. This frame is active when YaST is started and therefore it is marked by a bold white border. The active category is selected. The right frame provides an overview of the modules available in the active category. The bottom frame contains the buttons for and .
When you start the YaST control center, the category ↓ and ↑ to change the category. To select a module from the category, activate the right frame with → and then use ↓ and ↑ to select the module. Keep the arrow keys pressed to scroll through the list of available modules. After selecting a module, press Enter to start it.
is selected automatically. UseVarious buttons or selection fields in the module contain a highlighted letter (yellow by default). Use Alt–highlighted_letter to select a button directly instead of navigating there with →|. Exit the YaST control center by pressing Alt–Q or by selecting and pressing Enter.
If a YaST dialog gets corrupted or distorted (for example, while resizing the window), press Ctrl–L to refresh and restore its contents.
YaST in text mode has a set of advanced key combinations.
List advanced hotkeys.
Change color schema.
Quit the application.
Refresh screen.
List advanced hotkeys.
Dump dialog to the log file as a screenshot.
Open YDialogSpy to see the widget hierarchy.
If your window manager uses global Alt combinations, the Alt combinations in YaST might not work. Keys like Alt or Shift can also be occupied by the settings of the terminal.
Alt shortcuts can be executed with Esc instead of Alt. For example, Esc–H replaces Alt–H. (First press Esc, then press H.)
If the Alt and Shift combinations are occupied by the window manager or the terminal, use the combinations Ctrl–F (forward) and Ctrl–B (backward) instead.
The function keys (F1 ... F12) are also used for functions. Certain function keys might be occupied by the terminal and may not be available for YaST. However, the Alt key combinations and function keys should always be fully available on a pure text console.
Besides the text mode interface, YaST provides a pure command line interface. To get a list of YaST command line options, enter:
tux >
sudo
yast -h
If you know the package name and the package is provided by any of your
active installation repositories, you can use the command line option
-i
to install the package:
tux >
sudo
yast -i package_name
or
tux >
sudo
yast --install -i package_name
package_name can be a single short package name (for example gvim) installed with dependency checking, or the full path to an RPM package which is installed without dependency checking.
If you need a command line based software management utility with functionality beyond what YaST provides, consider using Zypper. This utility uses the same software management library that is also the foundation for the YaST package manager. The basic usage of Zypper is covered in Section 6.1, “Using Zypper”.
To save time, you can start individual YaST modules directly. To start a module, enter:
tux >
sudo
yast module_name
View a list of all module names available on your system with yast
-l
or yast --list
. Start the network module,
for example, with yast lan
.
To use YaST functionality in scripts, YaST provides command line support for individual modules. Not all modules have command line support. To display the available options of a module, enter:
tux >
sudo
yast module_name help
If a module does not provide command line support, it is started in a text mode and the following message appears:
This YaST module does not support the command line interface.
The following sections describe all YaST modules with command line support, together with a brief explanation of all their commands and available options.
All YaST modules support the following commands:
Lists all the module's supported commands together with their description:
tux >
sudo
yast lan help
Same as help
, but adds a detailed list of each
command's options together with their description:
tux >
sudo
yast lan longhelp
Same as longhelp
, but the output is structured as
an XML document and redirected to a file:
tux >
sudo
yast lan xmlhelp xmlfile=/tmp/yast_lan.xml
If you need to spend more time querying a module's settings, run the
interactive mode. The YaST shell opens, where
you can enter all the module's commands without the sudo yast
...
prefix. To leave the interactive mode, enter
exit
.
Adds a new add-on product from the specified path:
tux >
sudo
yast add-on http://server.name/directory/Lang-AddOn-CD1/
You can use the following protocols to specify the source path: http:// ftp:// nfs:// disk:// cd:// or dvd://.
Displays and configures the Linux Audit Framework. Refer to the
Book “Security and Hardening Guide” for more details. yast
audit-laf
accepts the following commands:
Sets an option:
tux >
sudo
yast audit-laf set log_file=/tmp/audit.log
For a complete list of options, run yast audit-laf set
help
.
Displays settings of an option:
tux >
sudo
yast audit-laf show diskspace space_left: 75 space_left_action: SYSLOG admin_space_left: 50 admin_space_left_action: SUSPEND action_mail_acct: root disk_full_action: SUSPEND disk_error_action: SUSPEND
For a complete list of options, run yast audit-laf show
help
.
Manages the DHCP server and configures its settings. yast
dhcp-server
accepts the following commands:
Disables the DHCP server service.
Enables the DHCP server service.
Configures settings for individual hosts.
Specifies to which network interface to listen to:
tux >
sudo
yast dhcp-server interface current Selected Interfaces: eth0 Other Interfaces: bond0, pbu, eth1
For a complete list of options, run yast dhcp-server interface
help
.
Manages global DHCP options. For a complete list of options, run
yast dhcp-server options help
.
Prints the status of the DHCP service.
Manages the DHCP subnet options. For a complete list of options, run
yast dhcp-server subnet help
.
Manages the DNS server configuration. yast dns-server
accepts the following commands:
Displays access control list settings:
tux >
sudo
yast dns-server acls show ACLs: ----- Name Type Value ---------------------------- any Predefined localips Predefined localnets Predefined none Predefined
Configures zone resource records:
tux >
sudo
yast dnsrecord add zone=example.org query=office.example.org type=NS value=ns3
For a complete list of options, run yast dns-server dnsrecord
help
.
Configures DNS forwarders:
tux >
sudo
yast dns-server forwarders add ip=10.0.0.100tux >
sudo
yast dns-server forwarders show [...] Forwarder IP ------------ 10.0.0.100
For a complete list of options, run yast dns-server forwarders
help
.
Handles 'A' and its related 'PTR' record at once:
tux >
sudo
yast dns-server host show zone=example.org
For a complete list of options, run yast dns-server host
help
.
Configures logging settings:
tux >
sudo
yast dns-server logging set updates=no transfers=yes
For a complete list of options, run yast dns-server logging
help
.
Configures zone mail servers:
tux >
sudo
yast dns-server mailserver add zone=example.org mx=mx1 priority=100
For a complete list of options, run yast dns-server mailserver
help
.
Configures zone name servers:
tux >
sudo
yast dns-server nameserver add zone=example.com ns=ns1
For a complete list of options, run yast dns-server nameserver
help
.
Configures the start of authority (SOA) record:
tux >
sudo
yast dns-server soa set zone=example.org serial=2006081623 ttl=2D3H20S
For a complete list of options, run yast dns-server soa
help
.
Manages the DNS server service:
tux >
sudo
yast dns-server startup atboot
For a complete list of options, run yast dns-server startup
help
.
Configures zone transport rules. For a complete list of options, run
yast dns-server transport help
.
Manages DNS zones:
tux >
sudo
yast dns-server zones add name=example.org zonetype=master
For a complete list of options, run yast dns-server zones
help
.
Prints information about all disks or partitions. The only supported
command is list
followed by either of the following
options:
Lists all configured disks in the system:
tux >
sudo
yast disk list disks Device | Size | FS Type | Mount Point | Label | Model ---------+------------+---------+-------------+-------+------------- /dev/sda | 119.24 GiB | | | | SSD 840 /dev/sdb | 60.84 GiB | | | | WD1003FBYX-0
Lists all partitions in the system:
tux >
sudo
yast disk list partitions Device | Size | FS Type | Mount Point | Label | Model ---------------+------------+---------+-------------+-------+------ /dev/sda1 | 1.00 GiB | Ext2 | /boot | | /dev/sdb1 | 1.00 GiB | Swap | swap | | /dev/sdc1 | 698.64 GiB | XFS | /mnt/extra | | /dev/vg00/home | 580.50 GiB | Ext3 | /home | | /dev/vg00/root | 100.00 GiB | Ext3 | / | | [...]
Configures FTP server settings. yast ftp-server
accepts
the following options:
Controls secure connections via SSL and TLS. SSL
options are valid for the vsftpd
only.
tux >
sudo
yast ftp-server SSL enabletux >
sudo
yast ftp-server TLS disable
Configures access permissions:
tux >
sudo
yast ftp-server access authen_only
For a complete list of options, run yast ftp-server access
help
.
Configures access permissions for anonymous users:
tux >
sudo
yast ftp-server anon_access can_upload
For a complete list of options, run yast ftp-server
anon_access help
.
Specifies the directory for anonymous users. The directory must already exist on the server:
tux >
sudo
yast ftp-server anon_dir set_anon_dir=/srv/ftp
For a complete list of options, run yast ftp-server anon_dir
help
.
Controls change root environment (chroot):
tux >
sudo
yast ftp-server chroot enabletux >
sudo
yast ftp-server chroot disable
Sets the maximum idle time in minutes before FTP server terminates the current connection:
tux >
sudo
yast ftp-server idle-time set_idle_time=15
Controls whether to save the log messages into a log file:
tux >
sudo
yast ftp-server logging enabletux >
sudo
yast ftp-server logging disable
Specifies the maximum number of concurrently connected clients:
tux >
sudo
yast ftp-server max_clients set_max_clients=1500
Specifies the maximum number of concurrently connected clients via IP:
tux >
sudo
yast ftp-server max_clients_ip set_max_clients=20
Specifies the maximum data transfer rate permitted for anonymous clients (KB/s):
tux >
sudo
yast ftp-server max_rate_anon set_max_rate=10000
Specifies the maximum data transfer rate permitted for locally authenticated users (KB/s):
tux >
sudo
yast ftp-server max_rate_authen set_max_rate=10000
Specifies the port range for passive connection replies:
tux >
sudo
yast ftp-server port_range set_min_port=20000 set_max_port=30000
For a complete list of options, run yast ftp-server port_range help
.
Displays FTP server settings.
Controls the FTP start-up method:
tux >
sudo
yast ftp-server startup atboot
For a complete list of options, run yast ftp-server startup
help
.
Specifies the file umask for authenticated:anonymous
users:
tux >
sudo
yast ftp-server umask set_umask=177:077
Specifies the text to display when someone connects to the FTP server:
tux >
sudo
yast ftp-server welcome_message set_message="hello everybody"
Configures the HTTP server (Apache2). yast http-server
accepts the following commands:
Configures the HTTP server host settings:
tux >
sudo
yast http-server configure host=main servername=www.example.com \ serveradmin=admin@example.com
For a complete list of options, run yast http-server configure
help
.
Configures virtual hosts:
tux >
sudo
yast http-server hosts create servername=www.example.com \ serveradmin=admin@example.com documentroot=/var/www
For a complete list of options, run yast http-server hosts
help
.
Specifies the ports and network addresses where the HTTP server should listen:
tux >
sudo
yast http-server listen add=81tux >
sudo
yast http-server listen list Listen Statements: ================== :80 :81tux >
sudo
yast http-server delete=80
For a complete list of options, run yast http-server listen
help
.
Enables or disables the wizard mode:
tux >
sudo
yast http-server mode wizard=on
Controls the Apache2 server modules:
tux >
sudo
yast http-server modules enable=php5,rewritetux >
sudo
yast http-server modules disable=ssltux >
sudo
http-server modules list [...] Enabled rewrite Disabled ssl Enabled php5 [...]
Configures kdump
settings. For more information
on kdump
, refer to the
Book “System Analysis and Tuning Guide”, Chapter 17 “Kexec and Kdump”, Section 17.7 “Basic Kdump Configuration”. yast kdump
accepts the following commands:
Copies the kernel into the dump directory.
Specifies the kernel_string part of the name
of the custom kernel. The naming scheme is
/boot/vmlinu[zx]-kernel_string[.gz]
.
tux >
sudo
yast kdump customkernel kernel=kdump
For a complete list of options, run yast kdump customkernel
help
.
Specifies the (compression) format of the dump kernel image. Available formats are 'none', 'ELF', 'compressed', or 'lzo':
tux >
sudo
yast kdump dumpformat dump_format=ELF
Specifies the dump level number in the range from 0 to 31:
tux >
sudo
yast kdump dumplevel dump_level=24
Specifies the destination for saving dump images:
tux >
sudo
kdump dumptarget taget=ssh server=name_server port=22 \ dir=/var/log/dump user=user_name
For a complete list of options, run yast kdump dumptarget
help
.
Controls whether the system should reboot immediately after saving the core in the kdump kernel:
tux >
sudo
yast kdump immediatereboot enabletux >
sudo
yast kdump immediatereboot disable
Specifies how many old dump images are kept. Specify zero to keep them all:
tux >
sudo
yast kdump keepolddumps no=5
Specifies the command line that needs to be passed off to the kdump kernel:
tux >
sudo
yast kdump kernelcommandline command="ro root=LABEL=/"
Specifies the command line that you need to append to the default command line string:
tux >
sudo
yast kdump kernelcommandlineappend command="ro root=LABEL=/"
Specifies an e-mail address for sending copies of notification messages:
tux >
sudo
yast kdump notificationcc email="user1@example.com user2@example.com"
Specifies an e-mail address for sending notification messages:
tux >
sudo
yast kdump notificationto email="user1@example.com user2@example.com"
Displays kdump
settings:
tux >
sudo
yast kdump show Kdump is disabled Dump Level: 31 Dump Format: compressed Dump Target Settings target: file file directory: /var/crash Kdump immediate reboots: Enabled Numbers of old dumps: 5
Specifies the file with the plain text SMTP password used for sending notification messages:
tux >
sudo
yast kdump smtppass pass=/path/to/file
Specifies the SMTP server host name used for sending notification messages:
tux >
sudo
yast kdump smtpserver server=smtp.server.com
Specifies the SMTP user name used for sending notification messages:
tux >
sudo
yast kdump smtpuser user=smtp_user
Enables or disables start-up options:
tux >
sudo
yast kdump startup enable alloc_mem=128,256tux >
sudo
yast kdump startup disable
Configures the system keyboard for virtual consoles. It does not affect
the keyboard settings in graphical desktop environments, such as GNOME
or KDE. yast keyboard
accepts the following commands:
Lists all available keyboard layouts.
Activates new keyboard layout setting:
tux >
sudo
yast keyboard set layout=czech
Displays the current keyboard configuration.
Configures network cards. yast lan
accepts the
following commands:
Configures a new network card:
tux >
sudo
yast lan add name=vlan50 ethdevice=eth0 bootproto=dhcp
For a complete list of options, run yast lan add
help
.
Deletes an existing network card:
tux >
sudo
yast lan delete id=0
Changes the configuration of an existing network card:
tux >
sudo
yast lan edit id=0 bootproto=dhcp
Displays a summary of network card configuration:
tux >
sudo
yast lan list id name, bootproto 0 Ethernet Card 0, NONE 1 Network Bridge, DHCP
Configures system languages. yast language
accepts the
following commands:
Lists all available languages.
Specifies the main system languages and secondary languages as well:
tux >
sudo
yast language set lang=cs_CZ languages=en_US,es_ES no_packages
Displays the configuration of the mail system:
tux >
sudo
yast mail summary
Controls the NFS client. yast nfs
accepts the following
commands:
Adds a new NFS mount:
tux >
sudo
yast nfs add spec=remote_host:/path/to/nfs/share file=/local/mount/point
For a complete list of options, run yast nfs add
help
.
Deletes an existing NFS mount:
tux >
sudo
yast nfs delete spec=remote_host:/path/to/nfs/share file=/local/mount/point
For a complete list of options, run yast nfs delete
help
.
Changes an existing NFS mount:
tux >
sudo
yast nfs edit spec=remote_host:/path/to/nfs/share \ file=/local/mount/point type=nfs4
For a complete list of options, run yast nfs edit
help
.
Lists existing NFS mounts:
tux >
sudo
yast nfs list Server Remote File System Mount Point Options ---------------------------------------------------------------- nfs.example.com /mnt /nfs/mnt nfs nfs.example.com /home/tux/nfs_share /nfs/tux nfs
Configures the NFS server. yast nfs-server
accepts the
following commands:
Adds a directory to export:
tux >
sudo
yast nfs-server add mountpoint=/nfs/export hosts=*.allowed_hosts.com
For a complete list of options, run yast nfs-server add
help
.
Deletes a directory from the NFS export:
tux >
sudo
yast nfs-server delete mountpoint=/nfs/export
Specifies additional parameters for the NFS server:
tux >
sudo
yast nfs-server set enablev4=yes security=yes
For a complete list of options, run yast nfs-server set
help
.
Starts the NFS server service:
tux >
sudo
yast nfs-server start
Stops the NFS server service:
tux >
sudo
yast nfs-server stop
Displays a summary of the NFS server configuration:
tux >
sudo
yast nfs-server summary NFS server is enabled NFS Exports * /mnt * /home NFSv4 support is enabled. The NFSv4 domain for idmapping is localdomain. NFS Security using GSS is enabled.
Configures the NIS client. yast nis
accepts the
following commands:
Changes global settings of a NIS client:
tux >
sudo
yast nis configure server=nis.example.com broadcast=yes
For a complete list of options, run yast nis configure
help
.
Disables the NIS client:
tux >
sudo
yast nis disable
Enables your machine as NIS client:
tux >
sudo
yast nis enable server=nis.example.com broadcast=yes automounter=yes
For a complete list of options, run yast nis enable
help
.
Shows available NIS servers for a given domain:
tux >
sudo
yast nis find domain=nisdomain.com
Displays a configuration summary of a NIS client.
Configures a NIS server. yast nis-server
accepts the
following commands:
Configures a NIS master server:
tux >
sudo
yast nis-server master domain=nisdomain.com yppasswd=yes
For a complete list of options, run yast nis-server master
help
.
Configures a NIS slave server:
tux >
sudo
yast nis-server slave domain=nisdomain.com master_ip=10.100.51.65
For a complete list of options, run yast nis-server slave
help
.
Stops a NIS server:
tux >
sudo
yast nis-server stop
Displays a configuration summary of a NIS server:
tux >
sudo
yast nis-server summary
Configures proxy settings. yast proxy
accepts the
following commands:
Specifies the authentication options for proxy:
tux >
sudo
yast proxy authentication username=tux password=secret
For a complete list of options, run yast proxy authentication
help
.
Enables or disables proxy settings.
Changes the current proxy settings:
tux >
sudo
yast proxy set https=proxy.example.com
For a complete list of options, run yast proxy set
help
.
Displays proxy settings.
Controls remote desktop settings. yast rdp
accepts the
following commands:
Allows remote access to the server's desktop:
tux >
sudo
yast rdp allow set=yes
Displays the remote desktop configuration summary.
Configures the Samba client settings. yast samba-client
accepts the following commands:
Changes global settings of Samba:
tux >
sudo
yast samba-client configure workgroup=FAMILY
Verifies if the machine is a member of a domain:
tux >
sudo
yast samba-client isdomainmember domain=SMB_DOMAIN
Makes the machine a member of a domain:
tux >
sudo
yast samba-client joindomain domain=SMB_DOMAIN user=username password=pwd
Enables or disables Winbind services (the
winbindd
daemon):
tux >
sudo
yast samba-client winbind enabletux >
sudo
yast samba-client winbind disable
Configures Samba server settings. yast samba-server
accepts the following commands:
Specifies the back-end for storing user information:
tux >
sudo
yast samba-server backend smbpasswd
For a complete list of options, run yast samba-server backend
help
.
Configures global settings of the Samba server:
tux >
sudo
yast samba-server configure workgroup=FAMILY description='Home server'
For a complete list of options, run yast samba-server
configure help
.
Displays a list of available shares:
tux >
sudo
yast samba-server list Status Type Name ============================== Disabled Disk profiles Enabled Disk print$ Enabled Disk homes Disabled Disk groups Enabled Disk movies Enabled Printer printers
Specifies the role of the Samba server:
tux >
sudo
yast samba-server role standalone
For a complete list of options, run yast samba-server role
help
.
Enables or disables the Samba services (smb
and nmb
):
tux >
sudo
yast samba-server service enabletux >
sudo
yast samba-server service disable
Manipulates a single Samba share:
tux >
sudo
yast samba-server share name=movies browseable=yes guest_ok=yes
For a complete list of options, run yast samba-server share
help
.
Controls the security level of the host. yast security
accepts the following commands:
Specifies the security level of the host:
tux >
sudo
yast security level server
For a complete list of options, run yast security level
help
.
Sets the value of specific options:
tux >
sudo
yast security set passwd=sha512 crack=yes
For a complete list of options, run yast security set
help
.
Displays a summary of the current security configuration:
sudo
yast security summary
Configures sound card settings. yast sound
accepts the
following commands:
Configures a new sound card. Without any parameters, the command adds the first one detected.
tux >
sudo
yast sound add card=0 volume=75
For a complete list of options, run yast sound add
help
.
Lists available volume channels of a sound card:
tux >
sudo
yast sound channels card=0 Master 75 PCM 100
Lists all available sound kernel modules:
tux >
sudo
yast sound modules snd-atiixp ATI IXP AC97 controller (snd-atiixp) snd-atiixp-modem ATI IXP MC97 controller (snd-atiixp-modem) snd-virtuoso Asus Virtuoso driver (snd-virtuoso) [...]
Plays a test sound on a sound card:
tux >
sudo
yast sound playtest card=0
Removes a configured sound card:
tux >
sudo
yast sound remove card=0tux >
sudo
yast sound remove all
Specifies new values for a sound card:
tux >
sudo
yast sound set card=0 volume=80
Displays detailed information about a sound card:
tux >
sudo
yast sound show card=0 Parameters of card 'ThinkPad X240' (using module snd-hda-intel): align_buffer_size Force buffer and period sizes to be multiple of 128 bytes. bdl_pos_adj BDL position adjustment offset. beep_mode Select HDA Beep registration mode (0=off, 1=on) (default=1). Default Value: 0 enable_msi Enable Message Signaled Interrupt (MSI) [...]
Prints a configuration summary for all sound cards on the system:
tux >
sudo
yast sound summary
Specifies the volume level of a sound card:
sudo
yast sound volume card=0 play
Controls the variables in files under /etc/sysconfig
.
yast sysconfig
accepts the following commands:
Sets empty value to a variable:
tux >
sudo
yast sysconfig clear=POSTFIX_LISTEN
If the variable is available in several files, use the VARIABLE_NAME$FILE_NAME syntax:
tux >
sudo
yast sysconfig clear=CONFIG_TYPE$/etc/sysconfig/mail
Displays detailed information about a variable:
tux >
sudo
yast sysconfig details variable=POSTFIX_LISTEN Description: Value: File: /etc/sysconfig/postfix Possible Values: Any value Default Value: Configuration Script: postfix Description: Comma separated list of IP's NOTE: If not set, LISTEN on all interfaces
Displays summary of modified variables. Use all
to
list all variables and their values:
tux >
sudo
yast sysconfig list all AOU_AUTO_AGREE_WITH_LICENSES="false" AOU_ENABLE_CRONJOB="true" AOU_INCLUDE_RECOMMENDS="false" [...]
Sets a value to a variable:
tux >
sudo
yast sysconfig set DISPLAYMANAGER=gdm
If the variable is available in several files, use the VARIABLE_NAME$FILE_NAME syntax:
tux >
sudo
yast sysconfig set CONFIG_TYPE$/etc/sysconfig/mail=advanced
Configures a TFTP server. yast tftp-server
accepts the
following commands:
Specifies the directory of the TFTP server:
tux >
sudo
yast tftp-server directory path=/srv/tftptux >
sudo
yast tftp-server directory list Directory Path: /srv/tftp
Controls the status of the TFTP server service:
tux >
sudo
yast tftp-server status disabletux >
sudo
yast tftp-server status show Service Status: falsetux >
sudo
yast tftp-server status enable
Configures the time zone. yast timezone
accepts the
following commands:
Lists all available time zones grouped by region:
tux >
sudo
yast timezone list Region: Africa Africa/Abidjan (Abidjan) Africa/Accra (Accra) Africa/Addis_Ababa (Addis Ababa) [...]
Specifies new values for the time zone configuration:
tux >
sudo
yast timezone set timezone=Europe/Prague hwclock=local
Displays the time zone configuration summary:
tux >
sudo
yast timezone summary Current Time Zone: Europe/Prague Hardware Clock Set To: Local time Current Time and Date: Mon 12. March 2018, 11:36:21 CET
Manages user accounts. yast users
accepts the following
commands:
Adds a new user:
tux >
sudo
yast users add username=user1 password=secret home=/home/user1
For a complete list of options, run yast users add
help
.
Deletes an existing user account:
tux >
sudo
yast users delete username=user1 delete_home
For a complete list of options, run yast users delete
help
.
Changes an existing user account:
tux >
sudo
yast users edit username=user1 password=new_secret
For a complete list of options, run yast users edit
help
.
Lists existing users filtered by user type:
tux >
sudo
yast users list system
For a complete list of options, run yast users list
help
.
Displays details about a user:
tux >
sudo
yast users show username=wwwrun Full Name: WWW daemon apache List of Groups: www Default Group: wwwrun Home Directory: /var/lib/wwwrun Login Shell: /sbin/nologin Login Name: wwwrun UID: 456
For a complete list of options, run yast users show
help
.
This chapter describes Zypper and RPM, two command line tools for managing
software. For a definition of the terminology used in this context (for
example, repository
, patch
, or
update
) refer to
Book “Deployment Guide”, Chapter 16 “Installing or Removing Software”, Section 16.1 “Definition of Terms”.
Zypper is a command line package manager for installing, updating and removing packages. It also manages repositories. It is especially useful for accomplishing remote software management tasks or managing software from shell scripts.
The general syntax of Zypper is:
zypper[--global-options]
COMMAND[--command-options]
[arguments]
The components enclosed in brackets are not required. See zypper
help
for a list of general options and all commands. To get help
for a specific command, type zypper help
COMMAND.
The simplest way to execute Zypper is to type its name, followed by a command. For example, to apply all needed patches to the system, use:
tux >
sudo
zypper patch
Additionally, you can choose from one or more global options by typing them immediately before the command:
tux >
sudo
zypper --non-interactive patch
In the above example, the option --non-interactive
means
that the command is run without asking anything (automatically applying
the default answers).
To use options that are specific to a particular command, type them immediately after the command:
tux >
sudo
zypper patch --auto-agree-with-licenses
In the above example, --auto-agree-with-licenses
is used
to apply all needed patches to a system without you being asked to
confirm any licenses. Instead, license will be accepted automatically.
Some commands require one or more arguments. For example, when using the
command install
, you need to specify which package or
which packages you want to install:
tux >
sudo
zypper install mplayer
Some options also require a single argument. The following command will list all known patterns:
tux >
zypper search -t pattern
You can combine all of the above. For example, the following command will
install the mc and vim packages from
the factory
repository while being verbose:
tux >
sudo
zypper -v install --from factory mc vim
The --from
option keeps all repositories
enabled (for solving any dependencies) while requesting the package from the
specified repository. --repo
is an alias for --from
, and you may use either one.
Most Zypper commands have a dry-run
option that does a
simulation of the given command. It can be used for test purposes.
tux >
sudo
zypper remove --dry-run MozillaFirefox
Zypper supports the global --userdata
STRING
option. You can specify a string
with this option, which gets written to Zypper's log files and plug-ins
(such as the Btrfs plug-in). It can be used to mark and identify
transactions in log files.
tux >
sudo
zypper --userdata STRING patch
Zypper subcommands are executables that are stored in the zypper_execdir,
/usr/lib/zypper/commands
. If a subcommand is not found
in the zypper_execdir, Zypper automatically searches the rest of your $PATH
for it. This enables writing your own local extensions and storing them in
userspace.
Executing subcommands in the Zypper shell, and using global Zypper options are not supported.
List your available subcommands:
tux >
zypper help subcommand
[...]
Available zypper subcommands in '/usr/lib/zypper/commands'
appstream-cache
lifecycle
migration
search-packages
Zypper subcommands available from elsewhere on your $PATH
<none>
View the help screen for a subcommand:
tux >
zypper help appstream-cache
To install or remove packages, use the following commands:
tux >
sudo
zypper install PACKAGE_NAMEtux >
sudo
zypper remove PACKAGE_NAME
Do not remove mandatory system packages like glibc , zypper , kernel . If they are removed, the system can become unstable or stop working altogether.
There are various ways to address packages with the commands
zypper install
and zypper remove
.
tux >
sudo
zypper install MozillaFirefox
tux >
sudo
zypper install MozillaFirefox-52.2
tux >
sudo
zypper install mozilla:MozillaFirefox
Where mozilla
is the alias of the repository from
which to install.
You can select all packages that have names starting or ending with a certain string. Use wild cards with care, especially when removing packages. The following command will install all packages starting with “Moz”:
tux >
sudo
zypper install 'Moz*'
-debuginfo
Packages
When debugging a problem, you sometimes need to temporarily install a
lot of -debuginfo
packages which give you more
information about running processes. After your debugging session
finishes and you need to clean the environment, run the following:
tux >
sudo
zypper remove '*-debuginfo'
For example, to install a package without knowing its name, capabilities come in handy. The following command will install the package MozillaFirefox:
tux >
sudo
zypper install firefox
Together with a capability, you can specify a hardware architecture and a version:
The name of the desired hardware architecture is appended to the
capability after a full stop. For example, to specify the AMD64/Intel 64
architectures (which in Zypper is named x86_64
),
use:
tux >
sudo
zypper install 'firefox.x86_64'
Versions must be appended to the end of the string and must be
preceded by an operator: <
(lesser than),
<=
(lesser than or equal), =
(equal), >=
(greater than or equal),
>
(greater than).
tux >
sudo
zypper install 'firefox>=52.2'
You can also combine a hardware architecture and version requirement:
tux >
sudo
zypper install 'firefox.x86_64>=52.2'
You can also specify a local or remote path to a package:
tux >
sudo
zypper install /tmp/install/MozillaFirefox.rpmtux >
sudo
zypper install http://download.example.com/MozillaFirefox.rpm
To install and remove packages simultaneously, use the
+/-
modifiers. To install emacs and
simultaneously remove vim , use:
tux >
sudo
zypper install emacs -vim
To remove emacs and simultaneously install vim , use:
tux >
sudo
zypper remove emacs +vim
To prevent the package name starting with the -
being
interpreted as a command option, always use it as the second argument. If
this is not possible, precede it with --
:
tux >
sudo
zypper install -emacs +vim # Wrongtux >
sudo
zypper install vim -emacs # Correcttux >
sudo
zypper install -- -emacs +vim # Correcttux >
sudo
zypper remove emacs +vim # Correct
If (together with a certain package), you automatically want to remove any
packages that become unneeded after removing the specified package, use the
--clean-deps
option:
tux >
sudo
zypper rm --clean-deps PACKAGE_NAME
By default, Zypper asks for a confirmation before installing or removing a
selected package, or when a problem occurs. You can override this behavior
using the --non-interactive
option. This option must be
given before the actual command (install
,
remove
, and patch
), as can be seen in
the following:
tux >
sudo
zypper--non-interactive
install PACKAGE_NAME
This option allows the use of Zypper in scripts and cron jobs.
To install the corresponding source package of a package, use:
tux >
zypper source-install PACKAGE_NAME
When executed as root
, the default location to install source
packages is /usr/src/packages/
and
~/rpmbuild
when run as user. These values can be
changed in your local rpm
configuration.
This command will also install the build dependencies of the specified
package. If you do not want this, add the switch -D
:
tux >
sudo
zypper source-install -D PACKAGE_NAME
To install only the build dependencies use -d
.
tux >
sudo
zypper source-install -d PACKAGE_NAME
Of course, this will only work if you have the repository with the source packages enabled in your repository list (it is added by default, but not enabled). See Section 6.1.6, “Managing Repositories with Zypper” for details on repository management.
A list of all source packages available in your repositories can be obtained with:
tux >
zypper search -t srcpackage
You can also download source packages for all installed packages to a local directory. To download source packages, use:
tux >
zypper source-download
The default download directory is
/var/cache/zypper/source-download
. You can change it
using the --directory
option. To only show missing or
extraneous packages without downloading or deleting anything, use the
--status
option. To delete extraneous source packages, use
the --delete
option. To disable deleting, use the
--no-delete
option.
Normally you can only install or refresh packages from enabled
repositories. The --plus-content
TAG
option helps you specify
repositories to be refreshed, temporarily enabled during the current Zypper
session, and disabled after it completes.
For example, to enable repositories that may provide additional
-debuginfo
or -debugsource
packages, use --plus-content debug
. You can specify this
option multiple times.
To temporarily enable such 'debug' repositories to install a specific
-debuginfo
package, use the option as follows:
tux >
sudo
zypper --plus-content debug \ install "debuginfo(build-id)=eb844a5c20c70a59fc693cd1061f851fb7d046f4"
The build-id
string is reported by
gdb
for missing debuginfo packages.
Repositories from the SUSE Linux Enterprise Desktop installation media are still
configured but disabled after successful installation. You can use the
--plus-content
option to install packages from the
installation media instead of the online repositories. Before calling
zypper
, ensure the media is available, for example by
inserting the DVD into the computer's drive.
To verify whether all dependencies are still fulfilled and to repair missing dependencies, use:
tux >
zypper verify
In addition to dependencies that must be fulfilled, some packages “recommend” other packages. These recommended packages are only installed if actually available and installable. In case recommended packages were made available after the recommending package has been installed (by adding additional packages or hardware), use the following command:
tux >
sudo
zypper install-new-recommends
This command is very useful after plugging in a Web cam or Wi-Fi device. It will install drivers for the device and related software, if available. Drivers and related software are only installable if certain hardware dependencies are fulfilled.
There are three different ways to update software using Zypper: by
installing patches, by installing a new version of a package or by updating
the entire distribution. The latter is achieved with zypper
dist-upgrade
. Upgrading SUSE Linux Enterprise Desktop is discussed in
Book “Upgrade Guide”, Chapter 1 “Upgrade Paths and Methods”.
Patching SUSE Linux Enterprise is the most reliable way to install new versions of installed packages. It guaranties that all required packages with correct versions are installed and ensures that package versions considered as conflicting are omitted.
To install all officially released patches that apply to your system, run:
tux >
sudo
zypper patch
All patches available from repositories configured on your computer are
checked for their relevance to your installation. If they are relevant (and
not classified as optional
or
feature
), they are installed immediately.
If zypper patch
succeeds, it is guaranteed that no
vulnerable version package is installed unless you confirmed the exception.
Note that the official update repository is only
available after registering your SUSE Linux Enterprise Desktop installation.
If a patch that is about to be installed includes changes that require a system reboot, you will be warned before.
The plain zypper patch
command does not apply patches
from third party repositories. To update also the third party repositories,
use the with-update
command option as follows:
tux >
sudo
zypper patch --with-update
To install also optional patches, use:
tux >
sudo
zypper patch --with-optional
To install all patches relating to a specific Bugzilla issue, use:
tux >
sudo
zypper patch --bugzilla=NUMBER
To install all patches relating to a specific CVE database entry, use:
tux >
sudo
zypper patch --cve=NUMBER
For example, to install a security patch with the CVE number
CVE-2010-2713
, execute:
tux >
sudo
zypper patch --cve=CVE-2010-2713
To install only patches which affect Zypper and the package management itself, use:
tux >
sudo
zypper patch --updatestack-only
Bear in mind that other command options that would also update other
repositories will be dropped if you use the
updatestack-only
command option.
To find out whether patches are available, Zypper allows viewing the following information:
To list the number of needed patches (patches that apply to your system
but are not yet installed), use patch-check
:
tux >
zypper patch-check
Loading repository data...
Reading installed packages...
5 patches needed (1 security patch)
This command can be combined with the
--updatestack-only
option to list only the patches
which affect Zypper and the package management itself.
To list all needed patches (patches that apply to your system but are
not yet installed), use list-patches
:
tux >
zypper list-patches
Loading repository data...
Reading installed packages...
Repository | Name | Version | Category | Status | Summary
---------------+-------------+---------+----------+---------+---------
SLES12-Updates | SUSE-2014-8 | 1 | security | needed | openssl: Update for OpenSSL
To list all patches available for SUSE Linux Enterprise Desktop, regardless of whether
they are already installed or apply to your installation, use
zypper patches
.
It is also possible to list and install patches relevant to specific
issues. To list specific patches, use the zypper
list-patches
command with the following options:
To list all needed patches that relate to Bugzilla issues, use the
option --bugzilla
.
To list patches for a specific bug, you can also specify a bug number:
--bugzilla=NUMBER
. To search
for patches relating to multiple Bugzilla issues, add commas between the
bug numbers, for example:
tux >
zypper list-patches --bugzilla=972197,956917
To list all needed patches that relate to an entry in the CVE database
(Common Vulnerabilities and Exposures), use the option
--cve
.
To list patches for a specific CVE database entry, you can also specify
a CVE number: --cve=NUMBER
.
To search for patches relating to multiple CVE database entries, add
commas between the CVE numbers, for example:
tux >
zypper list-patches --bugzilla=CVE-2016-2315,CVE-2016-2324
In the SUSE Linux Enterprise 15 codestream, some patches are automatically
retracted. Maintenance updates are carefully tested, because there
is a risk that an update contains a new bug. If an update proves to
contain a bug, a new update (with a higher version number) is
issued to revert the buggy update, and the buggy update is blocked
from being installed again. You can list retracted patches with
zypper
:
tux >
zypper lp --all |grep retracted
SLE-Module-Basesystem15-SP3-Updates | SUSE-SLE-Module-Basesystem-15-SP3-2021-1965 | recommended | important | --- | retracted | Recommended update for multipath-tools SLE-Module-Basesystem15-SP3-Updates | SUSE-SLE-Module-Basesystem-15-SP3-2021-2689 | security | important | --- | retracted | Security update for cpio SLE-Module-Basesystem15-SP3-Updates | SUSE-SLE-Module-Basesystem-15-SP3-2021-3655 | security | important | reboot | retracted | Security update for the Linux Kernel
See complete information on a retracted (or any) patch:
tux >
zypper patch-info SUSE-SLE-Product-SLES-15-2021-2689
Loading repository data... Reading installed packages... Information for patch SUSE-SLE-Product-SLES-15-2021-2689: --------------------------------------------------------- Repository : SLE-Product-SLES15-LTSS-Updates Name : SUSE-SLE-Product-SLES-15-2021-2689 Version : 1 Arch : noarch Vendor : maint-coord@suse.de Status : retracted Category : security Severity : important Created On : Mon 16 Aug 2021 03:44:00 AM PDT Interactive : --- Summary : Security update for cpio Description : This update for cpio fixes the following issues: It was possible to trigger Remote code execution due to a integer overflow (CVE-2021-38185, bsc#1189206) UPDATE: This update was buggy and could lead to hangs, so it has been retracted. There will be a follow up update. [...]
Information for patch openSUSE-SLE-15.3-2022-333: ------------------------------------------------- Repository : Update repository with updates from SUSE Linux Enterprise 15 Name : openSUSE-SLE-15.3-2022-333 Version : 1 Arch : noarch Vendor : maint-coord@suse.de Status : needed Category : security Severity : important Created On : Fri Feb 4 09:30:32 2022 Interactive : reboot Summary : Security update for xen Description : This update for xen fixes the following issues: - CVE-2022-23033: Fixed guest_physmap_remove_page not removing the p2m mappings. (XSA-393) (bsc#1194576) - CVE-2022-23034: Fixed possible DoS by a PV guest Xen while unmapping a grant. (XSA-394) (bsc#1194581) - CVE-2022-23035: Fixed insufficient cleanup of passed-through device IRQs. (XSA-395) (bsc#1194588) Provides : patch:openSUSE-SLE-15.3-2022-333 = 1 Conflicts : [22] xen.src < 4.14.3_06-150300.3.18.2 xen.noarch < 4.14.3_06-150300.3.18.2 xen.x86_64 < 4.14.3_06-150300.3.18.2 xen-devel.x86_64 < 4.14.3_06-150300.3.18.2 xen-devel.noarch < 4.14.3_06-150300.3.18.2 [...]
The above patch conflicts with the affected or vulnerable versions of
22 packages. If any of these affected or vulnerable packages are
installed, it triggers a conflict, and the patch is classified as
needed. zypper patch
tries to
install all available patches. If it encounters problems, it reports
them, thus informing you that not all updates are installed. The
conflict can be resolved by either updating the affected or vulnerable
packages or by removing them. Because SUSE update repositories also
ship fixed packages, updating is a standard way to resolve conflicts.
If the package cannot be updated—for example, due to dependency
issues or package locks—it is deleted after the user's approval.
To list all patches regardless of whether they are needed, use the option
--all
additionally. For example, to list all patches with
a CVE number assigned, use:
tux >
zypper list-patches --all --cve
Issue | No. | Patch | Category | Severity | Status
------+---------------+-------------------+-------------+-----------+----------
cve | CVE-2015-0287 | SUSE-SLE-Module.. | recommended | moderate | needed
cve | CVE-2014-3566 | SUSE-SLE-SERVER.. | recommended | moderate | not needed
[...]
If a repository contains only new packages, but does not provide patches,
zypper patch
does not show any effect. To update
all installed packages with newer available versions, use the following command:
tux >
sudo
zypper update
zypper update
ignores problematic packages.
For example, if a package is locked, zypper update
omits the package, even if a higher version of it is available. Conversely,
zypper patch
reports a conflict if the package is
considered vulnerable.
To update individual packages, specify the package with either the update or install command:
tux >
sudo
zypper update PACKAGE_NAMEtux >
sudo
zypper install PACKAGE_NAME
A list of all new installable packages can be obtained with the command:
tux >
zypper list-updates
Note that this command only lists packages that match the following criteria:
has the same vendor like the already installed package,
is provided by repositories with at least the same priority than the already installed package,
is installable (all dependencies are satisfied).
A list of all new available packages (regardless whether installable or not) can be obtained with:
tux >
sudo
zypper list-updates --all
To find out why a new package cannot be installed, use the zypper
install
or zypper update
command as described
above.
Whenever you remove a repository from Zypper or upgrade your system, some packages can get in an “orphaned” state. These orphaned packages belong to no active repository anymore. The following command gives you a list of these:
tux >
sudo
zypper packages --orphaned
With this list, you can decide if a package is still needed or can be removed safely.
When patching, updating or removing packages, there may be running processes
on the system which continue to use files having been deleted by the update
or removal. Use zypper ps
to list processes using deleted
files. In case the process belongs to a known service, the service name is
listed, making it easy to restart the service. By default zypper
ps
shows a table:
tux >
zypper ps
PID | PPID | UID | User | Command | Service | Files
------+------+-----+-------+--------------+--------------+-------------------
814 | 1 | 481 | avahi | avahi-daemon | avahi-daemon | /lib64/ld-2.19.s->
| | | | | | /lib64/libdl-2.1->
| | | | | | /lib64/libpthrea->
| | | | | | /lib64/libc-2.19->
[...]
PID: ID of the process |
PPID: ID of the parent process |
UID: ID of the user running the process |
Login: Login name of the user running the process |
Command: Command used to execute the process |
Service: Service name (only if command is associated with a system service) |
Files: The list of the deleted files |
The output format of zypper ps
can be controlled as
follows:
zypper ps
-s
Create a short table not showing the deleted files.
tux >
zypper ps -s
PID | PPID | UID | User | Command | Service
------+------+------+---------+--------------+--------------
814 | 1 | 481 | avahi | avahi-daemon | avahi-daemon
817 | 1 | 0 | root | irqbalance | irqbalance
1567 | 1 | 0 | root | sshd | sshd
1761 | 1 | 0 | root | master | postfix
1764 | 1761 | 51 | postfix | pickup | postfix
1765 | 1761 | 51 | postfix | qmgr | postfix
2031 | 2027 | 1000 | tux | bash |
zypper ps
-ss
Show only processes associated with a system service.
PID | PPID | UID | User | Command | Service ------+------+------+---------+--------------+-------------- 814 | 1 | 481 | avahi | avahi-daemon | avahi-daemon 817 | 1 | 0 | root | irqbalance | irqbalance 1567 | 1 | 0 | root | sshd | sshd 1761 | 1 | 0 | root | master | postfix 1764 | 1761 | 51 | postfix | pickup | postfix 1765 | 1761 | 51 | postfix | qmgr | postfix
zypper ps
-sss
Only show system services using deleted files.
avahi-daemon irqbalance postfix sshd
zypper ps
--print "systemctl status %s"
Show the commands to retrieve status information for services which might need a restart.
systemctl status avahi-daemon systemctl status irqbalance systemctl status postfix systemctl status sshd
For more information about service handling refer to
Chapter 15, The systemd
Daemon.
All installation or patch commands of Zypper rely on a list of known repositories. To list all repositories known to the system, use the command:
tux >
zypper repos
The result will look similar to the following output:
tux >
zypper repos
# | Alias | Name | Enabled | Refresh
--+--------------+---------------+---------+--------
1 | SLEHA-12-GEO | SLEHA-12-GEO | Yes | No
2 | SLEHA-12 | SLEHA-12 | Yes | No
3 | SLES12 | SLES12 | Yes | No
When specifying repositories in various commands, an alias, URI or
repository number from the zypper repos
command output
can be used. A repository alias is a short version of the repository name
for use in repository handling commands. Note that the repository numbers
can change after modifying the list of repositories. The alias will never
change by itself.
By default, details such as the URI or the priority of the repository are not displayed. Use the following command to list all details:
tux >
zypper repos -d
To add a repository, run
tux >
sudo
zypper addrepo URI ALIAS
URI can either be an Internet repository, a network resource, a directory or a CD or DVD (see https://en.opensuse.org/openSUSE:Libzypp_URIs for details). The ALIAS is a shorthand and unique identifier of the repository. You can freely choose it, with the only exception that it needs to be unique. Zypper will issue a warning if you specify an alias that is already in use.
zypper
enables you to fetch changes in packages from
configured repositories. To fetch the changes, run:
tux >
sudo
zypper refresh
zypper
By default, some commands perform refresh
automatically, so you do not need to run the command explicitly.
The refresh
command enables you to view changes also in
disabled repositories, by using the --plus-content
option:
tux >
sudo
zypper --plus-content refresh
This option fetches changes in repositories, but keeps the disabled repositories in the same state—disabled.
To remove a repository from the list, use the command zypper
removerepo
together with the alias or number of the repository
you want to delete. For example, to remove the repository
SLEHA-12-GEO
from Example 6.1, “Zypper—List of Known Repositories”, use one of the following commands:
tux >
sudo
zypper removerepo 1tux >
sudo
zypper removerepo "SLEHA-12-GEO"
Enable or disable repositories with zypper modifyrepo
.
You can also alter the repository's properties (such as refreshing
behavior, name or priority) with this command. The following command will
enable the repository named updates
, turn on
auto-refresh and set its priority to 20:
tux >
sudo
zypper modifyrepo -er -p 20 'updates'
Modifying repositories is not limited to a single repository—you can also operate on groups:
-a : all repositories |
-l : local repositories |
-t : remote repositories |
-m TYPE : repositories
of a certain type (where TYPE can be one of the
following: http , https , ftp ,
cd , dvd , dir , file ,
cifs , smb , nfs , hd ,
iso ) |
To rename a repository alias, use the renamerepo
command. The following example changes the alias from Mozilla
Firefox
to firefox
:
tux >
sudo
zypper renamerepo 'Mozilla Firefox' firefox
Zypper offers various methods to query repositories or packages. To get lists of all products, patterns, packages or patches available, use the following commands:
tux >
zypper productstux >
zypper patternstux >
zypper packagestux >
zypper patches
To query all repositories for certain packages, use
search
. To get information regarding particular packages,
use the info
command.
The zypper search
command works on package names, or,
optionally, on package summaries and descriptions. Strings wrapped in
/
are interpreted as regular expressions. By default,
the search is not case-sensitive.
fire
tux >
zypper search "fire"
MozillaFirefox
tux >
zypper search --match-exact "MozillaFirefox"
tux >
zypper search -d fire
tux >
zypper search -u fire
fir
not followed be e
tux >
zypper se "/fir[^e]/"
To search for packages both within and outside of currently enabled SLE
modules, use the search-packages
subcommand. This
command contacts the SUSE Customer Center and searches all modules for matching packages,
for example:
tux >
zypper search-packages package1 package2
zypper search-packages
provides the following options:
Search for an exact match of your search string: -x
,
--match-exact
Group the results by module (default: group by package):
-g,
--group-by-module
Display more detailed information about packages: -d
,
--details
Output search results in XML: --xmlout
To search for packages which provide a special capability, use the command
what-provides
. For example, if you want to know which
package provides the Perl module SVN::Core
, use the
following command:
tux >
zypper what-provides 'perl(SVN::Core)'
The what-provides
PACKAGE_NAME
is similar to
rpm -q --whatprovides
PACKAGE_NAME, but RPM is only able to query the
RPM database (that is the database of all installed packages). Zypper, on
the other hand, will tell you about providers of the capability from any
repository, not only those that are installed.
To query single packages, use info
with an exact package
name as an argument. This displays detailed information about a package. In
case the package name does not match any package name from repositories,
the command outputs detailed information for non-package matches. If you
request a specific type (by using the -t
option) and the
type does not exist, the command outputs other available matches but
without detailed information.
If you specify a source package, the command displays binary packages built from the source package. If you specify a binary package, the command outputs the source packages used to build the binary package.
To also show what is required/recommended by the package, use the options
--requires
and --recommends
:
tux >
zypper info --requires MozillaFirefox
SUSE products are generally supported for 10 years. Often, you can extend that standard lifecycle by using the extended support offerings of SUSE which add three years of support. Depending on your product, find the exact support lifecycle at https://www.suse.com/lifecycle.
To check the lifecycle of your product and the supported package, use the
zypper lifecycle
command as shown below:
root #
zypper lifecycle
Product end of support Codestream: SUSE Linux Enterprise Server 15 2028-07-31 SUSE Linux Enterprise Server 15 n/a* Module end of support Basesystem Module n/a* Server Applications Module n/a* Package end of support if different from product: SUSEConnect Now, installed 0.3.11-1.4, update available 0.3.11-3.3.1 ca-certificates-mozilla Now, installed 2.22-2.12, update available 2.24-4.3.1 curl Now, installed 7.60.0-1.1, update available 7.60.0-3.3.1 e2fsprogs Now, installed 1.43.8-2.44, update available 1.43.8-4.3.1 glibc Now, installed 2.26-11.8, update available 2.26-13.3.1
Zypper now comes with a configuration file, allowing you to permanently
change Zypper's behavior (either system-wide or user-specific). For
system-wide changes, edit /etc/zypp/zypper.conf
. For
user-specific changes, edit ~/.zypper.conf
. If
~/.zypper.conf
does not yet exist, you can use
/etc/zypp/zypper.conf
as a template: copy it to
~/.zypper.conf
and adjust it to your liking. Refer to
the comments in the file for help about the available options.
If you have trouble accessing packages from configured repositories (for example, Zypper cannot find a certain package even though you know it exists in one of the repositories), refreshing the repositories may help:
tux >
sudo
zypper refresh
If that does not help, try
tux >
sudo
zypper refresh -fdb
This forces a complete refresh and rebuild of the database, including a forced download of raw metadata.
If the Btrfs file system is used on the root partition and
snapper
is installed, Zypper automatically calls
snapper
when committing changes to the file system to
create appropriate file system snapshots. These snapshots can be used to
revert any changes made by Zypper. See Chapter 7, System Recovery and Snapshot Management with Snapper for
more information.
For more information on managing software from the command line, enter
zypper help
, zypper help
COMMAND or refer to the
zypper(8)
man page. For a complete and detailed command
reference, cheat sheets
with the most important commands,
and information on how to use Zypper in scripts and applications, refer to
https://en.opensuse.org/SDB:Zypper_usage. A list of
software changes for the latest SUSE Linux Enterprise Desktop version can be found at
https://en.opensuse.org/openSUSE:Zypper_versions.
RPM (RPM Package Manager) is used for managing software packages. Its main
commands are rpm
and rpmbuild
. The
powerful RPM database can be queried by the users, system administrators and
package builders for detailed information about the installed software.
rpm
has five modes: installing, uninstalling
(or updating) software packages, rebuilding the RPM database, querying RPM
bases or individual RPM archives, integrity checking of packages and signing
packages. rpmbuild
can be used to build installable
packages from pristine sources.
Installable RPM archives are packed in a special binary format. These
archives consist of the program files to install and certain meta information
used during the installation by rpm
to configure the
software package or stored in the RPM database for documentation purposes.
RPM archives normally have the extension .rpm
.
For several packages, the components needed for software development
(libraries, headers, include files, etc.) have been put into separate
packages. These development packages are only needed if you want to compile
software yourself (for example, the most recent GNOME packages). They can
be identified by the name extension -devel
, such as the
packages alsa-devel
and
gimp-devel
.
RPM packages have a GPG signature. To verify the signature of an RPM
package, use the command rpm --checksig
PACKAGE-1.2.3.rpm to determine whether the
package originates from SUSE or from another trustworthy facility. This is
especially recommended for update packages from the Internet.
While fixing issues in the operating system, you might need to install a Problem Temporary Fix (PTF) into a production system. The packages provided by SUSE are signed against a special PTF key. However, in contrast to SUSE Linux Enterprise 11, this key is not imported by default on SUSE Linux Enterprise 12 systems. To manually import the key, use the following command:
tux >
sudo
rpm --import \ /usr/share/doc/packages/suse-build-key/suse_ptf_key.asc
After importing the key, you can install PTF packages on your system.
Normally, the installation of an RPM archive is quite simple: rpm
-i
PACKAGE.rpm. With this command the
package is installed, but only if its dependencies are fulfilled and if
there are no conflicts with other packages. With an error message,
rpm
requests those packages that need to be installed to
meet dependency requirements. In the background, the RPM database ensures
that no conflicts arise—a specific file can only belong to one
package. By choosing different options, you can force rpm
to ignore these defaults, but this is only for experts. Otherwise, you risk
compromising the integrity of the system and possibly jeopardize the ability
to update the system.
The options -U
or --upgrade
and
-F
or --freshen
can be used to update a
package (for example, rpm -F
PACKAGE.rpm). This command removes the files of
the old version and immediately installs the new files. The difference
between the two versions is that -U
installs packages that
previously did not exist in the system, while -F
merely
updates previously installed packages. When updating, rpm
updates configuration files carefully using the following strategy:
If a configuration file was not changed by the system administrator,
rpm
installs the new version of the appropriate file.
No action by the system administrator is required.
If a configuration file was changed by the system administrator before the
update, rpm
saves the changed file with the extension
.rpmorig
or .rpmsave
(backup
file) and installs the version from the new package. This is done only if
the originally installed file and the newer version are different. If this is
the case, compare the backup file (.rpmorig
or
.rpmsave
) with the newly installed file and make your
changes again in the new file. Afterward, delete all
.rpmorig
and .rpmsave
files to
avoid problems with future updates.
.rpmnew
files appear if the configuration file
already exists and if the noreplace
label was specified in the .spec
file.
Following an update, .rpmsave
and
.rpmnew
files should be removed after comparing them,
so they do not obstruct future updates. The .rpmorig
extension is assigned if the file has not previously been recognized by the
RPM database.
Otherwise, .rpmsave
is used. In other words,
.rpmorig
results from updating from a foreign format to
RPM. .rpmsave
results from updating from an older RPM
to a newer RPM. .rpmnew
does not disclose any
information to whether the system administrator has made any changes to the
configuration file. A list of these files is available in
/var/adm/rpmconfigcheck
. Some configuration files (like
/etc/httpd/httpd.conf
) are not overwritten to allow
continued operation.
The -U
switch is not only an
equivalent to uninstalling with the -e
option and
installing with the -i
option. Use -U
whenever possible.
To remove a package, enter rpm -e
PACKAGE. This command only deletes the package if
there are no unresolved dependencies. It is theoretically impossible to
delete Tcl/Tk, for example, as long as another application requires it. Even
in this case, RPM calls for assistance from the database. If such a deletion
is, for whatever reason, impossible (even if no
additional dependencies exist), it may be helpful to rebuild the RPM
database using the option --rebuilddb
.
Delta RPM packages contain the difference between an old and a new version of an RPM package. Applying a delta RPM onto an old RPM results in a completely new RPM. It is not necessary to have a copy of the old RPM because a delta RPM can also work with an installed RPM. The delta RPM packages are even smaller in size than patch RPMs, which is an advantage when transferring update packages over the Internet. The drawback is that update operations with delta RPMs involved consume considerably more CPU cycles than plain or patch RPMs.
The makedeltarpm
and applydelta
binaries are part of the delta RPM suite (package
deltarpm
) and help you create and apply delta RPM
packages. With the following commands, you can create a delta RPM called
new.delta.rpm
. The following command assumes that
old.rpm
and new.rpm
are present:
tux >
sudo
makedeltarpm old.rpm new.rpm new.delta.rpm
Using applydeltarpm
, you can reconstruct the new RPM from
the file system if the old package is already installed:
tux >
sudo
applydeltarpm new.delta.rpm new.rpm
To derive it from the old RPM without accessing the file system, use the
-r
option:
tux >
sudo
applydeltarpm -r old.rpm new.delta.rpm new.rpm
See /usr/share/doc/packages/deltarpm/README
for
technical details.
With the -q
option rpm
initiates
queries, making it possible to inspect an RPM archive (by adding the option
-p
) and to query the RPM database of installed packages.
Several switches are available to specify the type of information required.
See Table 6.1, “The Most Important RPM Query Options”.
|
Package information |
|
File list |
|
Query the package that contains the file FILE (the full path must be specified with FILE) |
|
File list with status information (implies |
|
List only documentation files (implies |
|
List only configuration files (implies |
|
File list with complete details (to be used with |
|
List features of the package that another package can request with
|
|
Capabilities the package requires |
|
Installation scripts (preinstall, postinstall, uninstall) |
For example, the command rpm -q -i wget
displays the
information shown in Example 6.2, “rpm -q -i wget
”.
rpm -q -i wget
#Name : wget Version : 1.14 Release : 17.1 Architecture: x86_64 Install Date: Mon 30 Jan 2017 14:01:29 CET Group : Productivity/Networking/Web/Utilities Size : 2046483 License : GPL-3.0+ Signature : RSA/SHA256, Thu 08 Dec 2016 07:48:44 CET, Key ID 70af9e8139db7c82 Source RPM : wget-1.14-17.1.src.rpm Build Date : Thu 08 Dec 2016 07:48:34 CET Build Host : sheep09 Relocations : (not relocatable) Packager : https://www.suse.com/ Vendor : SUSE LLC <https://www.suse.com/> URL : http://www.gnu.org/software/wget/ Summary : A Tool for Mirroring FTP and HTTP Servers Description : Wget enables you to retrieve WWW documents or FTP files from a server. This can be done in script files or via the command line. Distribution: SUSE Linux Enterprise 12
The option -f
only works if you specify the complete file
name with its full path. Provide as many file names as desired. For example:
tux >
rpm -q -f /bin/rpm /usr/bin/wget
rpm-4.11.2-15.1.x86_64
wget-1.14-17.1.x86_64
If only part of the file name is known, use a shell script as shown in Example 6.3, “Script to Search for Packages”. Pass the partial file name to the script shown as a parameter when running it.
#! /bin/sh for i in $(rpm -q -a -l | grep $1); do echo "\"$i\" is in package:" rpm -q -f $i echo "" done
The command rpm -q --changelog
PACKAGE displays a detailed list of change
information about a specific package, sorted by date.
With the installed RPM database, verification checks can be made. Initiate
these with -V
, or --verify
. With this
option, rpm
shows all files in a package that have been
changed since installation. rpm
uses eight character
symbols to give some hints about the following changes:
|
MD5 check sum |
|
File size |
|
Symbolic link |
|
Modification time |
|
Major and minor device numbers |
|
Owner |
|
Group |
|
Mode (permissions and file type) |
In the case of configuration files, the letter c
is
printed. For example, for changes to /etc/wgetrc
(wget
package):
tux >
rpm -V wget
S.5....T c /etc/wgetrc
The files of the RPM database are placed in
/var/lib/rpm
. If the partition
/usr
has a size of 1 GB, this database can occupy
nearly 30 MB, especially after a complete update. If the database is
much larger than expected, it is useful to rebuild the database with the
option --rebuilddb
. Before doing this, make a backup of the
old database. The cron
script
cron.daily
makes daily copies of the database (packed
with gzip) and stores them in /var/adm/backup/rpmdb
.
The number of copies is controlled by the variable
MAX_RPMDB_BACKUPS
(default: 5
) in
/etc/sysconfig/backup
. The size of a single backup is
approximately 1 MB for 1 GB in /usr
.
All source packages carry a .src.rpm
extension (source
RPM).
Source packages can be copied from the installation medium to the hard disk
and unpacked with YaST. They are not, however, marked as installed
([i]
) in the package manager. This is because the source
packages are not entered in the RPM database. Only
installed operating system software is listed in the
RPM database. When you “install” a source package, only the
source code is added to the system.
The following directories must be available for rpm
and
rpmbuild
in /usr/src/packages
(unless you specified custom settings in a file like
/etc/rpmrc
):
SOURCES
for the original sources (.tar.bz2
or
.tar.gz
files, etc.) and for distribution-specific
adjustments (mostly .diff
or
.patch
files)
SPECS
for the .spec
files, similar to a meta Makefile,
which control the build process
BUILD
all the sources are unpacked, patched and compiled in this directory
RPMS
where the completed binary packages are stored
SRPMS
here are the source RPMs
When you install a source package with YaST, all the necessary components
are installed in /usr/src/packages
: the sources and the
adjustments in SOURCES
and the relevant
.spec
file in SPECS
.
Do not experiment with system components
(glibc
,
rpm
, etc.), because this
endangers the stability of your system.
The following example uses the wget.src.rpm
package.
After installing the source package, you should have files similar to those
in the following list:
/usr/src/packages/SOURCES/wget-1.11.4.tar.bz2 /usr/src/packages/SOURCES/wgetrc.patch /usr/src/packages/SPECS/wget.spec
rpmbuild
-bX
/usr/src/packages/SPECS/wget.spec
starts the
compilation. X is a wild card for various stages
of the build process (see the output of --help
or the RPM
documentation for details). The following is merely a brief explanation:
-bp
Prepare sources in /usr/src/packages/BUILD
: unpack
and patch.
-bc
Do the same as -bp
, but with additional compilation.
-bi
Do the same as -bp
, but with additional installation of
the built software. Caution: if the package does not support the
BuildRoot feature, you might overwrite configuration files.
-bb
Do the same as -bi
, but with the additional creation of
the binary package. If the compile was successful, the binary should be
in /usr/src/packages/RPMS
.
-ba
Do the same as -bb
, but with the additional creation of
the source RPM. If the compilation was successful, the binary should be
in /usr/src/packages/SRPMS
.
--short-circuit
Skip some steps.
The binary RPM created can now be installed with rpm
-i
or, preferably, with rpm
-U
. Installation with rpm
makes it
appear in the RPM database.
Keep in mind, the BuildRoot
directive in the spec file is
deprecated since SUSE Linux Enterprise Desktop 12. If you still need this feature, use the
--buildroot
option as a workaround. For more detailed background information, see the support
database at https://www.suse.com/support/kb/doc?id=7017104.
The danger with many packages is that unwanted files are added to the
running system during the build process. To prevent this use
build
, which creates a defined environment in which
the package is built. To establish this chroot environment, the
build
script must be provided with a complete package
tree. This tree can be made available on the hard disk, via NFS, or from
DVD. Set the position with build --rpms
DIRECTORY. Unlike rpm
, the
build
command looks for the .spec
file in the source directory. To build wget
(like in
the above example) with the DVD mounted in the system under
/media/dvd
, use the following commands as
root
:
root #
cd /usr/src/packages/SOURCES/root #
mv ../SPECS/wget.spec .root #
build --rpms /media/dvd/suse/ wget.spec
Subsequently, a minimum environment is established at
/var/tmp/build-root
. The package is built in this
environment. Upon completion, the resulting packages are located in
/var/tmp/build-root/usr/src/packages/RPMS
.
The build
script offers several additional options. For
example, cause the script to prefer your own RPMs, omit the initialization
of the build environment or limit the rpm
command to one
of the above-mentioned stages. Access additional information with
build
--help
and by reading the
build
man page.
Midnight Commander (mc
) can display the contents of RPM
archives and copy parts of them. It represents archives as virtual file
systems, offering all usual menu options of Midnight Commander. Display the
HEADER
with F3. View the archive
structure with the cursor keys and Enter. Copy archive
components with F5.
A full-featured package manager is available as a YaST module. For details, see Book “Deployment Guide”, Chapter 16 “Installing or Removing Software”.
Snapper allows creating and managing file system snapshots. File system snapshots allow keeping a copy of the state of a file system at a certain point of time. The standard setup of Snapper is designed to allow rolling back system changes. However, you can also use it to create on-disk backups of user data. As the basis for this functionality, Snapper uses the Btrfs file system or thinly-provisioned LVM volumes with an XFS or Ext4 file system.
Snapper has a command-line interface and a YaST interface. Snapper lets you create and manage file system snapshots on the following types of file systems:
Btrfs, a copy-on-write file system for Linux that natively supports file system snapshots of subvolumes. (Subvolumes are separately mountable file systems within a physical partition.)
You can also boot from Btrfs
snapshots. For more
information, see Section 7.3, “System Rollback by Booting from Snapshots”.
Thinly-provisioned LVM volumes formatted with XFS or Ext4.
Using Snapper, you can perform the following tasks:
Undo system changes made by zypper
and YaST. See
Section 7.2, “Using Snapper to Undo Changes” for details.
Restore files from previous snapshots. See Section 7.2.2, “Using Snapper to Restore Files” for details.
Do a system rollback by booting from a snapshot. See Section 7.3, “System Rollback by Booting from Snapshots” for details.
Manually create and manage snapshots, within the running system. See Section 7.6, “Manually Creating and Managing Snapshots” for details.
Snapper on SUSE Linux Enterprise Desktop is set up as an undo and recovery
tool for system changes. By default, the root partition
(/
) of SUSE Linux Enterprise Desktop is formatted with
Btrfs
. Taking snapshots is automatically enabled if the
root partition (/
) is big enough (more
than approximately 16 GB). By default, snapshots are disabled on partitions
other than /
.
If you disabled Snapper during the installation, you can enable it at any time later. To do so, create a default Snapper configuration for the root file system by running:
tux >
sudo
snapper -c root create-config /
Afterward enable the different snapshot types as described in Section 7.1.3.1, “Disabling/Enabling Snapshots”.
Note that on a Btrfs root file system, snapshots require a file system with subvolumes set up as proposed by the installer and a partition size of at least 16 GB.
When a snapshot is created, both the snapshot and the original point to the
same blocks in the file system. So, initially a snapshot does not occupy
additional disk space. If data in the original file system is modified,
changed data blocks are copied while the old data blocks are kept for the
snapshot. Therefore, a snapshot occupies the same amount of space as the
data modified. So, over time, the amount of space a snapshot allocates,
constantly grows. As a consequence, deleting files from a
Btrfs
file system containing snapshots may
not free disk space!
Snapshots always reside on the same partition or subvolume on which the snapshot has been taken. It is not possible to store snapshots on a different partition or subvolume.
As a result, partitions containing snapshots need to be larger than partitions not containing snapshots. The exact amount depends strongly on the number of snapshots you keep and the amount of data modifications. As a rule of thumb, give partitions twice as much space as you normally would. To prevent disks from running out of space, old snapshots are automatically cleaned up. Refer to Section 7.1.3.4, “Controlling Snapshot Archiving” for details.
Although snapshots themselves do not differ in a technical sense, we distinguish between three types of snapshots, based on the events that trigger them:
A single snapshot is created every hour. Old snapshots are automatically deleted. By default, the first snapshot of the last ten days, months, and years are kept. Using the YaST OS installation method (default), timeline snapshots are enabled, except for the root file system.
Whenever one or more packages are installed with YaST or Zypper, a
pair of snapshots is created: one before the installation starts
(“Pre”) and another one after the installation has finished
(“Post”). In case an important system component such as the
kernel has been installed, the snapshot pair is marked as important
(important=yes
). Old snapshots are automatically
deleted. By default the last ten important snapshots and the last ten
“regular” (including administration snapshots) snapshots
are kept. Installation snapshots are enabled by default.
Whenever you administrate the system with YaST, a pair of snapshots is created: one when a YaST module is started (“Pre”) and another when the module is closed (“Post”). Old snapshots are automatically deleted. By default the last ten important snapshots and the last ten “regular” snapshots (including installation snapshots) are kept. Administration snapshots are enabled by default.
Some directories need to be excluded from snapshots for different reasons. The following list shows all directories that are excluded:
/boot/grub2/i386-pc
,
/boot/grub2/x86_64-efi
,
/boot/grub2/powerpc-ieee1275
,
/boot/grub2/s390x-emu
A rollback of the boot loader configuration is not supported. The directories listed above are architecture-specific. The first two directories are present on AMD64/Intel 64 machines, the latter two on IBM POWER and on IBM Z, respectively.
/home
If /home
does not reside on a separate partition, it
is excluded to avoid data loss on rollbacks.
/opt
Third-party products usually get installed to /opt
. It
is excluded to avoid uninstalling these applications on rollbacks.
/srv
Contains data for Web and FTP servers. It is excluded to avoid data loss on rollbacks.
/tmp
All directories containing temporary files and caches are excluded from snapshots.
/usr/local
This directory is used when manually installing software. It is excluded to avoid uninstalling these installations on rollbacks.
/var
This directory contains many variable files, including logs, temporary
caches, third party products in /var/opt
, and is the
default location for virtual machine images and databases. Therefore this
subvolume is created to exclude all of this variable data from snapshots
and has Copy-On-Write disabled.
SUSE Linux Enterprise Desktop comes with a reasonable default setup, which should be sufficient for most use cases. However, all aspects of taking automatic snapshots and snapshot keeping can be configured according to your needs.
Each of the three snapshot types (timeline, installation, administration) can be enabled or disabled independently.
Enabling.
snapper -c root set-config "TIMELINE_CREATE=yes"
Disabling.
snapper -c root set-config "TIMELINE_CREATE=no"
Using the YaST OS installation method (default), timeline snapshots are enabled, except for the root file system.
Enabling:
Install the package
snapper-zypp-plugin
Disabling:
Uninstall the package
snapper-zypp-plugin
Installation snapshots are enabled by default.
Enabling:
Set USE_SNAPPER
to yes
in
/etc/sysconfig/yast2
.
Disabling:
Set USE_SNAPPER
to no
in
/etc/sysconfig/yast2
.
Administration snapshots are enabled by default.
Taking snapshot pairs upon installing packages with YaST or Zypper is
handled by the
snapper-zypp-plugin
. An XML
configuration file, /etc/snapper/zypp-plugin.conf
defines, when to make snapshots. By default the file looks like the
following:
1 <?xml version="1.0" encoding="utf-8"?> 2 <snapper-zypp-plugin-conf> 3 <solvables> 4 <solvable match="w"1 important="true"2>kernel-*3</solvable> 5 <solvable match="w" important="true">dracut</solvable> 6 <solvable match="w" important="true">glibc</solvable> 7 <solvable match="w" important="true">systemd*</solvable> 8 <solvable match="w" important="true">udev</solvable> 9 <solvable match="w">*</solvable>4 10 </solvables> 11 </snapper-zypp-plugin-conf>
The match attribute defines whether the pattern is a Unix shell-style
wild card ( | |
If the given pattern matches and the corresponding package is marked as important (for example kernel packages), the snapshot will also be marked as important. | |
Pattern to match a package name. Based on the setting of the
| |
This line unconditionally matches all packages. |
With this configuration snapshot, pairs are made whenever a package is installed (line 9). When the kernel, dracut, glibc, systemd, or udev packages marked as important are installed, the snapshot pair will also be marked as important (lines 4 to 8). All rules are evaluated.
To disable a rule, either delete it or deactivate it using XML comments. To prevent the system from making snapshot pairs for every package installation for example, comment line 9:
1 <?xml version="1.0" encoding="utf-8"?> 2 <snapper-zypp-plugin-conf> 3 <solvables> 4 <solvable match="w" important="true">kernel-*</solvable> 5 <solvable match="w" important="true">dracut</solvable> 6 <solvable match="w" important="true">glibc</solvable> 7 <solvable match="w" important="true">systemd*</solvable> 8 <solvable match="w" important="true">udev</solvable> 9 <!-- <solvable match="w">*</solvable> --> 10 </solvables> 11 </snapper-zypp-plugin-conf>
Creating a new subvolume underneath the /
hierarchy
and permanently mounting it is supported. Such a subvolume will be
excluded from snapshots. You need to make sure not to create it inside an
existing snapshot, since you would not be able to delete snapshots anymore
after a rollback.
SUSE Linux Enterprise Desktop is configured with the /@/
subvolume
which serves as an independent root for permanent subvolumes such as
/opt
, /srv
,
/home
and others. Any new subvolumes you create and
permanently mount need to be created in this initial root file system.
To do so, run the following commands. In this example, a new subvolume
/usr/important
is created from
/dev/sda2
.
tux >
sudo
mount /dev/sda2 -o subvol=@ /mnttux >
sudo
btrfs subvolume create /mnt/usr/importanttux >
sudo
umount /mnt
The corresponding entry in /etc/fstab
needs to look
like the following:
/dev/sda2 /usr/important btrfs subvol=@/usr/important 0 0
A subvolume may contain files that constantly change, such as
virtualized disk images, database files, or log files. If so, consider
disabling the copy-on-write feature for this volume, to avoid duplication
of disk blocks. Use the nodatacow
mount option in
/etc/fstab
to do so:
/dev/sda2 /usr/important btrfs nodatacow,subvol=@/usr/important 0 0
To alternatively disable copy-on-write for single files or directories,
use the command chattr +C
PATH
.
Snapshots occupy disk space. To prevent disks from running out of space and thus causing system outages, old snapshots are automatically deleted. By default, up to ten important installation and administration snapshots and up to ten regular installation and administration snapshots are kept. If these snapshots occupy more than 50% of the root file system size, additional snapshots will be deleted. A minimum of four important and two regular snapshots are always kept.
Refer to Section 7.5.1, “Managing Existing Configurations” for instructions on how to change these values.
Apart from snapshots on Btrfs
file systems, Snapper
also supports taking snapshots on thinly-provisioned LVM volumes (snapshots
on regular LVM volumes are not supported) formatted
with XFS, Ext4 or Ext3. For more information and setup instructions on LVM
volumes, refer to Book “Deployment Guide”, Chapter 6 “Expert Partitioner”, Section 6.2 “LVM Configuration”.
To use Snapper on a thinly-provisioned LVM volume you need to create a
Snapper configuration for it. On LVM it is required to specify the file
system with
--fstype=lvm(FILESYSTEM)
.
ext3
, etx4
or xfs
are valid values for FILESYSTEM. Example:
tux >
sudo
snapper -c lvm create-config --fstype="lvm(xfs)" /thin_lvm
You can adjust this configuration according to your needs as described in Section 7.5.1, “Managing Existing Configurations”.
Snapper on SUSE Linux Enterprise Desktop is preconfigured to serve as a tool that lets you
undo changes made by zypper
and YaST. For this purpose,
Snapper is configured to create a pair of snapshots before and after each
run of zypper
and YaST. Snapper also lets you restore
system files that have been accidentally deleted or modified. Timeline
snapshots for the root partition need to be enabled for this
purpose—see
Section 7.1.3.1, “Disabling/Enabling Snapshots” for details.
By default, automatic snapshots as described above are configured for the
root partition and its subvolumes. To make snapshots available for other
partitions such as /home
for example, you can create
custom configurations.
When working with snapshots to restore data, it is important to know that there are two fundamentally different scenarios Snapper can handle:
When undoing changes as described in the following, two snapshots are being compared and the changes between these two snapshots are made undone. Using this method also allows to explicitly select the files that should be restored.
When doing rollbacks as described in Section 7.3, “System Rollback by Booting from Snapshots”, the system is reset to the state at which the snapshot was taken.
When undoing changes, it is also possible to compare a snapshot against the current system. When restoring all files from such a comparison, this will have the same result as doing a rollback. However, using the method described in Section 7.3, “System Rollback by Booting from Snapshots” for rollbacks should be preferred, since it is faster and allows you to review the system before doing the rollback.
There is no mechanism to ensure data consistency when creating a snapshot.
Whenever a file (for example, a database) is written at the same time as
the snapshot is being created, it will result in a corrupted or partly written
file. Restoring such a file will cause problems. Furthermore, some system
files such as /etc/mtab
must never be restored.
Therefore it is strongly recommended to always closely
review the list of changed files and their diffs. Only restore files that
really belong to the action you want to revert.
If you set up the root partition with Btrfs
during the
installation, Snapper—preconfigured for doing rollbacks of YaST or
Zypper changes—will automatically be installed. Every time you start
a YaST module or a Zypper transaction, two snapshots are created: a
“pre-snapshot” capturing the state of the file system before
the start of the module and a “post-snapshot” after the module
has been finished.
Using the YaST Snapper module or the snapper
command
line tool, you can undo the changes made by YaST/Zypper by restoring
files from the “pre-snapshot”. Comparing two snapshots the
tools also allow you to see which files have been changed. You can also
display the differences between two versions of a file (diff).
Start the yast2 snapper
.
Make sure
is set to . This is always the case unless you have manually added own Snapper configurations.
Choose a pair of pre- and post-snapshots from the list. Both, YaST and
Zypper snapshot pairs are of the type zypp(y2base)
in the
; Zypper snapshots are labeled
zypp(zypper)
.
Click
to open the list of files that differ between the two snapshots.Review the list of files. To display a “diff” between the pre- and post-version of a file, select it from the list.
To restore one or more files, select the relevant files or directories by activating the respective check box. Click
and confirm the action by clicking .To restore a single file, activate its diff view by clicking its name. Click
and confirm your choice with .snapper
Command #
Get a list of YaST and Zypper snapshots by running snapper
list -t pre-post
. YaST snapshots are labeled
as yast MODULE_NAME
in the
; Zypper snapshots are labeled
zypp(zypper)
.
tux >
sudo
snapper list -t pre-post Pre # | Post # | Pre Date | Post Date | Description ------+--------+-------------------------------+-------------------------------+-------------- 311 | 312 | Tue 06 May 2018 14:05:46 CEST | Tue 06 May 2018 14:05:52 CEST | zypp(y2base) 340 | 341 | Wed 07 May 2018 16:15:10 CEST | Wed 07 May 2018 16:15:16 CEST | zypp(zypper) 342 | 343 | Wed 07 May 2018 16:20:38 CEST | Wed 07 May 2018 16:20:42 CEST | zypp(y2base) 344 | 345 | Wed 07 May 2018 16:21:23 CEST | Wed 07 May 2018 16:21:24 CEST | zypp(zypper) 346 | 347 | Wed 07 May 2018 16:41:06 CEST | Wed 07 May 2018 16:41:10 CEST | zypp(y2base) 348 | 349 | Wed 07 May 2018 16:44:50 CEST | Wed 07 May 2018 16:44:53 CEST | zypp(y2base) 350 | 351 | Wed 07 May 2018 16:46:27 CEST | Wed 07 May 2018 16:46:38 CEST | zypp(y2base)
Get a list of changed files for a snapshot pair with snapper
status
PRE..POST. Files
with content changes are marked with , files that
have been added are marked with and deleted files
are marked with .
tux >
sudo
snapper status 350..351 +..... /usr/share/doc/packages/mikachan-fonts +..... /usr/share/doc/packages/mikachan-fonts/COPYING +..... /usr/share/doc/packages/mikachan-fonts/dl.html c..... /usr/share/fonts/truetype/fonts.dir c..... /usr/share/fonts/truetype/fonts.scale +..... /usr/share/fonts/truetype/みかちゃん-p.ttf +..... /usr/share/fonts/truetype/みかちゃん-pb.ttf +..... /usr/share/fonts/truetype/みかちゃん-ps.ttf +..... /usr/share/fonts/truetype/みかちゃん.ttf c..... /var/cache/fontconfig/7ef2298fde41cc6eeb7af42e48b7d293-x86_64.cache-4 c..... /var/lib/rpm/Basenames c..... /var/lib/rpm/Dirnames c..... /var/lib/rpm/Group c..... /var/lib/rpm/Installtid c..... /var/lib/rpm/Name c..... /var/lib/rpm/Packages c..... /var/lib/rpm/Providename c..... /var/lib/rpm/Requirename c..... /var/lib/rpm/Sha1header c..... /var/lib/rpm/Sigmd5
To display the diff for a certain file, run snapper
diff
PRE..POST
FILENAME. If you do not specify
FILENAME, a diff for all files will be
displayed.
tux >
sudo
snapper diff 350..351 /usr/share/fonts/truetype/fonts.scale --- /.snapshots/350/snapshot/usr/share/fonts/truetype/fonts.scale 2014-04-23 15:58:57.000000000 +0200 +++ /.snapshots/351/snapshot/usr/share/fonts/truetype/fonts.scale 2014-05-07 16:46:31.000000000 +0200 @@ -1,4 +1,4 @@ -1174 +1486 ds=y:ai=0.2:luximr.ttf -b&h-luxi mono-bold-i-normal--0-0-0-0-c-0-iso10646-1 ds=y:ai=0.2:luximr.ttf -b&h-luxi mono-bold-i-normal--0-0-0-0-c-0-iso8859-1 [...]
To restore one or more files run snapper -v undochange
PRE..POST
FILENAMES. If you do not specify a
FILENAMES, all changed files will be restored.
tux >
sudo
snapper -v undochange 350..351 create:0 modify:13 delete:7 undoing change... deleting /usr/share/doc/packages/mikachan-fonts deleting /usr/share/doc/packages/mikachan-fonts/COPYING deleting /usr/share/doc/packages/mikachan-fonts/dl.html deleting /usr/share/fonts/truetype/みかちゃん-p.ttf deleting /usr/share/fonts/truetype/みかちゃん-pb.ttf deleting /usr/share/fonts/truetype/みかちゃん-ps.ttf deleting /usr/share/fonts/truetype/みかちゃん.ttf modifying /usr/share/fonts/truetype/fonts.dir modifying /usr/share/fonts/truetype/fonts.scale modifying /var/cache/fontconfig/7ef2298fde41cc6eeb7af42e48b7d293-x86_64.cache-4 modifying /var/lib/rpm/Basenames modifying /var/lib/rpm/Dirnames modifying /var/lib/rpm/Group modifying /var/lib/rpm/Installtid modifying /var/lib/rpm/Name modifying /var/lib/rpm/Packages modifying /var/lib/rpm/Providename modifying /var/lib/rpm/Requirename modifying /var/lib/rpm/Sha1header modifying /var/lib/rpm/Sigmd5 undoing change done
Reverting user additions via undoing changes with Snapper is not recommended. Since certain directories are excluded from snapshots, files belonging to these users will remain in the file system. If a user with the same user ID as a deleted user is created, this user will inherit the files. Therefore it is strongly recommended to use the YaST
tool to remove users.Apart from the installation and administration snapshots, Snapper creates timeline snapshots. You can use these backup snapshots to restore files that have accidentally been deleted or to restore a previous version of a file. By using Snapper's diff feature you can also find out which modifications have been made at a certain point of time.
Being able to restore files is especially interesting for data, which may
reside on subvolumes or partitions for which snapshots are not taken by
default. To be able to restore files from home directories, for example,
create a separate Snapper configuration for /home
doing automatic timeline snapshots. See
Section 7.5, “Creating and Modifying Snapper Configurations” for instructions.
Snapshots taken from the root file system (defined by Snapper's root configuration), can be used to do a system rollback. The recommended way to do such a rollback is to boot from the snapshot and then perform the rollback. See Section 7.3, “System Rollback by Booting from Snapshots” for details.
Performing a rollback would also be possible by restoring all files from a
root file system snapshot as described below. However, this is not
recommended. You may restore single files, for example a configuration
file from the /etc
directory, but not the
complete list of files from the snapshot.
This restriction only affects snapshots taken from the root file system!
Start the yast2 snapper
.
Choose the
from which to choose a snapshot.Select a timeline snapshot from which to restore a file and choose
. Timeline snapshots are of the type with a description value of .Select a file from the text box by clicking the file name. The difference between the snapshot version and the current system is shown. Activate the check box to select the file for restore. Do so for all files you want to restore.
Click
and confirm the action by clicking .snapper
Command #Get a list of timeline snapshots for a specific configuration by running the following command:
tux >
sudo
snapper -c CONFIG list -t single | grep timeline
CONFIG needs to be replaced by an existing
Snapper configuration. Use snapper list-configs
to
display a list.
Get a list of changed files for a given snapshot by running the following command:
tux >
sudo
snapper -c CONFIG status SNAPSHOT_ID..0
Replace SNAPSHOT_ID by the ID for the snapshot from which you want to restore the file(s).
Optionally list the differences between the current file version and the one from the snapshot by running
tux >
sudo
snapper -c CONFIG diff SNAPSHOT_ID..0 FILE NAME
If you do not specify <FILE NAME>, the difference for all files are shown.
To restore one or more files, run
tux >
sudo
snapper -c CONFIG -v undochange SNAPSHOT_ID..0 FILENAME1 FILENAME2
If you do not specify file names, all changed files will be restored.
The GRUB 2 version included on SUSE Linux Enterprise Desktop can boot from Btrfs snapshots.
Together with Snapper's rollback feature, this allows to recover a
misconfigured system. Only snapshots created for the default Snapper
configuration (root
) are bootable.
As of SUSE Linux Enterprise Desktop 15 SP1 system rollbacks are only supported if the default subvolume configuration of the root partition has not been changed.
When booting a snapshot, the parts of the file system included in the snapshot are mounted read-only; all other file systems and parts that are excluded from snapshots are mounted read-write and can be modified.
When working with snapshots to restore data, it is important to know that there are two fundamentally different scenarios Snapper can handle:
When undoing changes as described in Section 7.2, “Using Snapper to Undo Changes”, two snapshots are compared and the changes between these two snapshots are reverted. Using this method also allows to explicitly exclude selected files from being restored.
When doing rollbacks as described in the following, the system is reset to the state at which the snapshot was taken.
To do a rollback from a bootable snapshot, the following requirements must be met. When doing a default installation, the system is set up accordingly.
The root file system needs to be Btrfs. Booting from LVM volume snapshots is not supported.
The root file system needs to be on a single device, a single partition
and a single subvolume. Directories that are excluded from snapshots such
as /srv
(see Section 7.1.2, “Directories That Are Excluded from Snapshots”
for a full list) may reside on separate partitions.
The system needs to be bootable via the installed boot loader.
To perform a rollback from a bootable snapshot, do as follows:
Boot the system. In the boot menu choose
and select the snapshot you want to boot. The list of snapshots is listed by date—the most recent snapshot is listed first.Log in to the system. Carefully check whether everything works as expected. Note that you cannot write to any directory that is part of the snapshot. Data you write to other directories will not get lost, regardless of what you do next.
Depending on whether you want to perform the rollback or not, choose your next step:
If the system is in a state where you do not want to do a rollback, reboot to boot into the current system state. You can then choose a different snapshot, or start the rescue system.
To perform the rollback, run
tux >
sudo
snapper rollback
and reboot afterward. On the boot screen, choose the default boot entry to reboot into the reinstated system. A snapshot of the file system status before the rollback is created. The default subvolume for root will be replaced with a fresh read-write snapshot. For details, see Section 7.3.1, “Snapshots after Rollback”.
It is useful to add a description for the snapshot with the -d
option.
For example:
New file system root since rollback on DATE TIME
If snapshots are not disabled during installation, an initial bootable
snapshot is created at the end of the initial system installation. You can
go back to that state at any time by booting this snapshot. The snapshot
can be identified by the description after installation
.
A bootable snapshot is also created when starting a system upgrade to a service pack or a new major release (provided snapshots are not disabled).
Before a rollback is performed, a snapshot of the running file system is created. The description references the ID of the snapshot that was restored in the rollback.
Snapshots created by rollbacks receive the value number
for the Cleanup
attribute. The rollback snapshots are
therefore automatically deleted when the set number of snapshots is reached.
Refer to Section 7.7, “Automatic Snapshot Clean-Up” for details.
If the snapshot contains important data, extract the data from the snapshot
before it is removed.
For example, after a fresh installation the following snapshots are available on the system:
root #
snapper
--iso list Type | # | | Cleanup | Description | Userdata -------+---+ ... +---------+-----------------------+-------------- single | 0 | | | current | single | 1 | | | first root filesystem | single | 2 | | number | after installation | important=yes
After running sudo snapper rollback
snapshot
3
is created and contains the state of the system
before the rollback was executed. Snapshot 4
is
the new default Btrfs subvolume and thus the system after a reboot.
root #
snapper
--iso list Type | # | | Cleanup | Description | Userdata -------+---+ ... +---------+-----------------------+-------------- single | 0 | | | current | single | 1 | | number | first root filesystem | single | 2 | | number | after installation | important=yes single | 3 | | number | rollback backup of #1 | important=yes single | 4 | | | |
To boot from a snapshot, reboot your machine and choose ↓ and ↑ to navigate and press Enter to activate the selected snapshot. Activating a snapshot from the boot menu does not reboot the machine immediately, but rather opens the boot loader of the selected snapshot.
. A screen listing all bootable snapshots opens. The most recent snapshot is listed first, the oldest last. Use the keysEach snapshot entry in the boot loader follows a naming scheme which makes it possible to identify it easily:
[*]1OS2 (KERNEL3,DATE4TTIME5,DESCRIPTION6)
If the snapshot was marked | |
Operating system label. | |
Date in the format | |
Time in the format | |
This field contains a description of the snapshot. In case of a manually
created snapshot this is the string created with the option
|
It is possible to replace the default string in the description field of a snapshot with a custom string. This is for example useful if an automatically created description is not sufficient, or a user-provided description is too long. To set a custom string STRING for snapshot NUMBER, use the following command:
tux >
sudo
snapper modify --userdata "bootloader=STRING" NUMBER
The description should be no longer than 25 characters—everything that exceeds this size will not be readable on the boot screen.
A complete system rollback, restoring the complete system to the identical state as it was in when a snapshot was taken, is not possible.
Root file system snapshots do not contain all directories. See Section 7.1.2, “Directories That Are Excluded from Snapshots” for details and reasons. As a general consequence, data from these directories is not restored, resulting in the following limitations.
Applications and add-ons installing data in subvolumes excluded from
the snapshot, such as /opt
, may not work after a
rollback, if others parts of the application data are also installed on
subvolumes included in the snapshot. Re-install the application or the
add-on to solve this problem.
If an application had changed file permissions and/or ownership in between snapshot and current system, the application may not be able to access these files. Reset permissions and/or ownership for the affected files after the rollback.
If a service or an application has established a new data format in between snapshot and current system, the application may not be able to read the affected data files after a rollback.
Subvolumes like /srv
may contain a mixture of code
and data. A rollback may result in non-functional code. A downgrade of
the PHP version, for example, may result in broken PHP scripts for the
Web server.
If a rollback removes users from the system, data that is owned by
these users in directories excluded from the snapshot, is not removed.
If a user with the same user ID is created, this user will inherit the
files. Use a tool like find
to locate and remove
orphaned files.
A rollback of the boot loader is not possible, since all
“stages” of the boot loader must fit together. This cannot be
guaranteed when doing rollbacks of /boot
.
You may enable snapshots for users' /home
directories, which supports a number of use cases:
Individual users may manage their own snapshots and rollbacks.
System users, for example database, system, and network admins who want to track copies of configuration files, documentation, and so on.
Samba shares with home directories and Btrfs backend.
Each user's directory is a Btrfs subvolume of /home
.
It is possible to set this up manually
(see Section 7.4.3, “Manually Enabling Snapshots in Home Directories”). However, a
more convenient way is to use pam_snapper
.
The pam_snapper
package installs the
pam_snapper.so
module and helper scripts, which
automate user creation and Snapper configuration.
pam_snapper
provides integration with the
useradd
command, pluggable
authentication modules (PAM), and Snapper. By default it creates snapshots
at user login and logout, and also creates time-based snapshots as some
users remain logged in for extended periods of time. You may change the
defaults using the normal Snapper commands and configuration files.
The easiest way is to start with a new /home
directory formatted with Btrfs, and no existing users. Install
pam_snapper
:
root #
zypper in pam_snapper
Add this line to /etc/pam.d/common-session
:
session optional pam_snapper.so
Use the /usr/lib/pam_snapper/pam_snapper_useradd.sh
script to create a new user and home directory. By default the script
performs a dry run. Edit the script to change
DRYRUN=1
to DRYRUN=0
. Now you
can create a new user:
root #
/usr/lib/pam_snapper/pam_snapper_useradd.sh \
username group passwd=password
Create subvolume '/home/username'
useradd: warning: the home directory already exists.
Not copying any file from skel directory into it.
The files from /etc/skel
will be copied
into the user's home directory at their first login. Verify that
the user's configuration was created by listing your Snapper
configurations:
root #
snapper list --all
Config: home_username, subvolume: /home/username
Type | # | Pre # | Date | User | Cleanup | Description | Userdata
-------+---+-------+------+------+---------+-------------+---------
single | 0 | | | root | | current |
Over time, this output will become populated with a list of snapshots, which the user can manage with the standard Snapper commands.
Remove users with the
/usr/lib/pam_snapper/pam_snapper_userdel.sh
script. By default it performs a dry run, so edit it to change
DRYRUN=1
to DRYRUN=0
. This
removes the user, the user's home subvolume, Snapper configuration,
and deletes all snapshots.
root #
/usr/lib/pam_snapper/pam_snapper_userdel.sh username
These are the steps for manually setting up users' home directories
with Snapper. /home
must be formatted with Btrfs,
and the users not yet created.
root #
btrfs subvol create /home/usernameroot #
snapper -c home_username create-config /home/usernameroot #
sed -i -e "s/ALLOW_USERS=\"\"/ALLOW_USERS=\"username\"/g" \ /etc/snapper/configs/home_usernameroot #
yast users add username=username home=/home/username password=passwordroot #
chown username.group /home/usernameroot #
chmod 755 /home/username/.snapshots
The way Snapper behaves is defined in a configuration file that is specific
for each partition or Btrfs
subvolume. These
configuration files reside under /etc/snapper/configs/
.
In case the root file system is big enough (approximately 12 GB), snapshots
are automatically enabled for the root file system /
upon installation. The corresponding default configuration is named
root
. It creates and manages the YaST and Zypper
snapshot. See Section 7.5.1.1, “Configuration Data” for a list
of the default values.
As explained in Section 7.1, “Default Setup”, enabling snapshots requires additional free space in the root file system. The amount depends on the amount of packages installed and the amount of changes made to the volume that is included in snapshots. The snapshot frequency and the number of snapshots that get archived also matter.
There is a minimum root file system size that is required to automatically
enable snapshots during the installation. Currently this size is
approximately 12 GB. This value may change in the future, depending on
architecture and the size of the base system. It depends on the values for
the following tags in the file /control.xml
from the
installation media:
<root_base_size> <btrfs_increase_percentage>
It is calculated with the following formula: ROOT_BASE_SIZE * (1 + BTRFS_INCREASE_PERCENTAGE/100)
Keep in mind that this value is a minimum size. Consider using more space for the root file system. As a rule of thumb, double the size you would use when not having enabled snapshots.
You may create your own configurations for other partitions formatted with
Btrfs
or existing subvolumes on a
Btrfs
partition. In the following example we will set up
a Snapper configuration for backing up the Web server data residing on a
separate, Btrfs
-formatted partition mounted at
/srv/www
.
After a configuration has been created, you can either use
snapper
itself or the YaST
module to restore files from these snapshots. In YaST you need to select
your , while you need to specify
your configuration for snapper
with the global switch
-c
(for example, snapper -c myconfig
list
).
To create a new Snapper configuration, run snapper
create-config
:
tux >
sudo
snapper -c www-data1 create-config /srv/www2
Name of configuration file. | |
Mount point of the partition or |
This command will create a new configuration file
/etc/snapper/configs/www-data
with reasonable default
values (taken from
/etc/snapper/config-templates/default
). Refer to
Section 7.5.1, “Managing Existing Configurations” for instructions on how to
adjust these defaults.
Default values for a new configuration are taken from
/etc/snapper/config-templates/default
. To use your own
set of defaults, create a copy of this file in the same directory and
adjust it to your needs. To use it, specify the -t
option
with the create-config command:
tux >
sudo
snapper -c www-data create-config -t MY_DEFAULTS /srv/www
The snapper
command offers several subcommands for managing
existing configurations. You can list, show, delete and modify them:
Use the subcommand snapper list-configs
to get all
existing configurations:
tux >
sudo
snapper list-configs Config | Subvolume -------+---------- root | / usr | /usr local | /local
Use the subcommand snapper -c
CONFIG get-config
to display the
specified configuration. Replace CONFIG with
one of the configuration names shown by
snapper list-configs
.
For more information about the configuration options, see
Section 7.5.1.1, “Configuration Data”.
To display the default configuration, run:
tux >
sudo
snapper -c root get-config
Use the subcommand snapper -c CONFIG
set-config
OPTION=VALUE
to modify an option in the specified configuration.
Replace CONFIG with one of the
configuration names shown by snapper list-configs
.
Possible values for OPTION and
VALUE are listed in Section 7.5.1.1, “Configuration Data”.
Use the subcommand snapper -c
CONFIG delete-config
to delete a
configuration. Replace CONFIG with one of the
configuration names shown by snapper list-configs
.
Each configuration contains a list of options that can be modified from
the command line. The following list provides details for each option. To
change a value, run snapper -c CONFIG
set-config
"KEY=VALUE"
.
ALLOW_GROUPS
,
ALLOW_USERS
Granting permissions to use snapshots to regular users. See Section 7.5.1.2, “Using Snapper as Regular User” for more information.
The default value is ""
.
BACKGROUND_COMPARISON
Defines whether pre and post snapshots should be compared in the background after creation.
The default value is "yes"
.
EMPTY_*
Defines the clean-up algorithm for snapshots pairs with identical pre and post snapshots. See Section 7.7.3, “Cleaning Up Snapshot Pairs That Do Not Differ” for details.
FSTYPE
File system type of the partition. Do not change.
The default value is "btrfs"
.
NUMBER_*
Defines the clean-up algorithm for installation and admin snapshots. See Section 7.7.1, “Cleaning Up Numbered Snapshots” for details.
QGROUP
/ SPACE_LIMIT
Adds quota support to the clean-up algorithms. See Section 7.7.5, “Adding Disk Quota Support” for details.
SUBVOLUME
Mount point of the partition or subvolume to snapshot. Do not change.
The default value is "/"
.
SYNC_ACL
If Snapper is used by regular users (see
Section 7.5.1.2, “Using Snapper as Regular User”), the users must be able to
access the .snapshot
directories and to read files
within them. If SYNC_ACL is set to yes
, Snapper
automatically makes them accessible using ACLs for users and groups
from the ALLOW_USERS or ALLOW_GROUPS entries.
The default value is "no"
.
TIMELINE_CREATE
If set to yes
, hourly snapshots are created. Valid
values: yes
, no
.
The default value is "no"
.
TIMELINE_CLEANUP
/
TIMELINE_LIMIT_*
Defines the clean-up algorithm for timeline snapshots. See Section 7.7.2, “Cleaning Up Timeline Snapshots” for details.
By default Snapper can only be used by root
. However, there are
cases in which certain groups or users need to be able to create snapshots
or undo changes by reverting to a snapshot:
Web site administrators who want to take snapshots of
/srv/www
Users who want to take a snapshot of their home directory
For these purposes, you can create Snapper configurations that grant
permissions to users or/and groups. The corresponding
.snapshots
directory needs to be readable and
accessible by the specified users. The easiest way to achieve this is to
set the SYNC_ACL option to yes
.
Note that all steps in this procedure need to be run by root
.
If a Snapper configuration does not exist yet, create one for the partition or subvolume on which the user should be able to use Snapper. Refer to Section 7.5, “Creating and Modifying Snapper Configurations” for instructions. Example:
tux >
sudo
snapper --config web_data create /srv/www
The configuration file is created under
/etc/snapper/configs/CONFIG
,
where CONFIG is the value you specified with
-c/--config
in the previous step (for example
/etc/snapper/configs/web_data
). Adjust it according
to your needs. For more information, see
Section 7.5.1, “Managing Existing Configurations”.
Set values for ALLOW_USERS
and/or
ALLOW_GROUPS
to grant permissions to users and/or groups,
respectively. Multiple entries need to be separated by
Space. To grant permissions to the user
www_admin
for example, run:
tux >
sudo
snapper -c web_data set-config "ALLOW_USERS=www_admin" SYNC_ACL="yes"
The given Snapper configuration can now be used by the specified user(s)
and/or group(s). You can test it with the list
command, for example:
www_admin:~ >
snapper -c web_data list
Snapper is not restricted to creating and managing snapshots automatically by configuration; you can also create snapshot pairs (“before and after”) or single snapshots manually using either the command-line tool or the YaST module.
All Snapper operations are carried out for an existing configuration (see
Section 7.5, “Creating and Modifying Snapper Configurations” for details). You can only take
snapshots of partitions or volumes for which a configuration exists. By
default the system configuration (root
) is used.
To create or manage snapshots for your own configuration you need to
explicitly choose it. Use the
drop-down box in YaST or specify the -c
on the command
line (snapper -c MYCONFIG
COMMAND
).
Each snapshot consists of the snapshot itself and some metadata. When
creating a snapshot you also need to specify the metadata. Modifying a
snapshot means changing its metadata—you cannot modify its content.
Use snapper list
to show existing snapshots and their
metadata:
snapper --config home list
Lists snapshots for the configuration home
. To list
snapshots for the default configuration (root), use snapper -c
root list
or snapper list
.
snapper list -a
Lists snapshots for all existing configurations.
snapper list -t pre-post
Lists all pre and post snapshot pairs for the default
(root
) configuration.
snapper list -t single
Lists all snapshots of the type single
for the
default (root
) configuration.
The following metadata is available for each snapshot:
Type: Snapshot type, see Section 7.6.1.1, “Snapshot Types” for details. This data cannot be changed.
Number: Unique number of the snapshot. This data cannot be changed.
Pre Number: Specifies the number of the corresponding pre snapshot. For snapshots of type post only. This data cannot be changed.
Description: A description of the snapshot.
Userdata: An extended description where
you can specify custom data in the form of a comma-separated key=value
list: reason=testing, project=foo
. This field is also
used to mark a snapshot as important (important=yes
)
and to list the user that created the snapshot
(user=tux).
Cleanup-Algorithm: Cleanup-algorithm for the snapshot, see Section 7.7, “Automatic Snapshot Clean-Up” for details.
Snapper knows three different types of snapshots: pre, post, and single. Physically they do not differ, but Snapper handles them differently.
pre
Snapshot of a file system before a modification.
Each pre
snapshot corresponds to a
post
snapshot.
For example, this is used for the automatic YaST/Zypper snapshots.
post
Snapshot of a file system after a modification.
Each post
snapshot corresponds to a
pre
snapshot.
For example, this is used for the automatic YaST/Zypper snapshots.
single
Stand-alone snapshot. For example, this is used for the automatic hourly snapshots. This is the default type when creating snapshots.
Snapper provides three algorithms to clean up old snapshots. The
algorithms are executed in a daily
cron
job.
It is possible to define the
number of different types of snapshots to keep in the Snapper
configuration (see Section 7.5.1, “Managing Existing Configurations” for
details).
Deletes old snapshots when a certain snapshot count is reached.
Deletes old snapshots having passed a certain age, but keeps several hourly, daily, monthly, and yearly snapshots.
Deletes pre/post snapshot pairs with empty diffs.
To create a snapshot, run snapper create
or
click in the YaST module
. The following examples explain how to create
snapshots from the command line.
The YaST interface for Snapper is not explicitly described here but
provides equivalent functionality.
Always specify a meaningful description to later be able to
identify its purpose. You can also specify additional information via
the option --userdata
.
snapper create --description "Snapshot for week 2
2014"
Creates a stand-alone snapshot (type single) for the default
(root
) configuration with a description. Because no
cleanup-algorithm is specified, the snapshot will never be deleted
automatically.
snapper --config home create --description "Cleanup in
~tux"
Creates a stand-alone snapshot (type single) for a custom configuration
named home
with a description. Because no
cleanup-algorithm is specified, the snapshot will never be deleted
automatically.
snapper --config home create --description "Daily data
backup" --cleanup-algorithm timeline
>
Creates a stand-alone snapshot (type single) for a custom configuration
named home
with a description. The snapshot will
automatically be deleted when it meets the criteria specified for the
timeline cleanup-algorithm in the configuration.
snapper create --type pre --print-number --description
"Before the Apache config cleanup" --userdata "important=yes"
Creates a snapshot of the type pre
and prints the
snapshot number. First command needed to create a pair of snapshots used
to save a “before” and “after” state. The
snapshot is marked as important.
snapper create --type post --pre-number 30 --description
"After the Apache config cleanup" --userdata "important=yes"
Creates a snapshot of the type post
paired with the
pre
snapshot number 30
. Second
command needed to create a pair of snapshots used to save a
“before” and “after” state. The snapshot is
marked as important.
snapper create --command COMMAND
--description "Before and after COMMAND"
Automatically creates a snapshot pair before and after running COMMAND. This option is only available when using snapper on the command line.
Snapper allows you to modify the description, the cleanup algorithm, and the user data of a snapshot. All other metadata cannot be changed. The following examples explain how to modify snapshots from the command line. It should be easy to adopt them when using the YaST interface.
To modify a snapshot on the command line, you need to know its number. Use
snapper list
to display all snapshots
and their numbers.
The YaST
module already lists all snapshots. Choose one from the list and click .snapper modify --cleanup-algorithm "timeline"
10
Modifies the metadata of snapshot 10 for the default
(root
) configuration. The cleanup algorithm is set to
timeline
.
snapper --config home modify --description "daily backup"
-cleanup-algorithm "timeline" 120
Modifies the metadata of snapshot 120 for a custom configuration named
home
. A new description is set and the cleanup
algorithm is unset.
To delete a snapshot with the YaST
module, choose a snapshot from the list and click .
To delete a snapshot with the command-line tool, you need to know its
number. Get it by running snapper list
. To delete a
snapshot, run snapper delete
NUMBER.
Deleting the current default subvolume snapshot is not allowed.
When deleting snapshots with Snapper, the freed space will be claimed by a
Btrfs process running in the background. Thus the visibility and the
availability of free space is delayed. In case you need space freed by
deleting a snapshot to be available immediately, use the option
--sync
with the delete command.
When deleting a pre
snapshot, you should always delete
its corresponding post
snapshot (and vice versa).
snapper delete 65
Deletes snapshot 65 for the default (root
)
configuration.
snapper -c home delete 89 90
Deletes snapshots 89 and 90 for a custom configuration named
home
.
snapper delete --sync 23
Deletes snapshot 23 for the default (root
)
configuration and makes the freed space available immediately.
Sometimes the Btrfs snapshot is present but the XML file containing the metadata for Snapper is missing. In this case the snapshot is not visible for Snapper and needs to be deleted manually:
btrfs subvolume delete /.snapshots/SNAPSHOTNUMBER/snapshot rm -rf /.snapshots/SNAPSHOTNUMBER
If you delete snapshots to free space on your hard disk, make sure to delete old snapshots first. The older a snapshot is, the more disk space it occupies.
Snapshots are also automatically deleted by a daily cron job. Refer to Section 7.6.1.2, “Cleanup Algorithms” for details.
Snapshots occupy disk space and over time the amount of disk space occupied by the snapshots may become large. To prevent disks from running out of space, Snapper offers algorithms to automatically delete old snapshots. These algorithms differentiate between timeline snapshots and numbered snapshots (administration plus installation snapshot pairs). You can specify the number of snapshots to keep for each type.
In addition to that, you can optionally specify a disk space quota, defining the maximum amount of disk space the snapshots may occupy. It is also possible to automatically delete pre and post snapshots pairs that do not differ.
A clean-up algorithm is always bound to a single Snapper configuration, so you need to configure algorithms for each configuration. To prevent certain snapshots from being automatically deleted, refer to Can a snapshot be protected from deletion? .
The default setup (root
) is configured to do clean-up
for numbered snapshots and empty pre and post snapshot pairs. Quota support
is enabled—snapshots may not occupy more than 50% of the available
disk space of the root partition. Timeline snapshots are disabled by
default, therefore the timeline clean-up algorithm is also disabled.
Cleaning up numbered snapshots—administration plus installation snapshot pairs—is controlled by the following parameters of a Snapper configuration.
NUMBER_CLEANUP
Enables or disables clean-up of installation and admin snapshot pairs.
If enabled, snapshot pairs are deleted when the total snapshot count
exceeds a number specified with NUMBER_LIMIT
and/or
NUMBER_LIMIT_IMPORTANT
and an
age specified with NUMBER_MIN_AGE
. Valid values:
yes
(enable), no
(disable).
The default value is "yes"
.
Example command to change or set:
tux >
sudo
snapper -c CONFIG set-config "NUMBER_CLEANUP=no"
NUMBER_LIMIT
/
NUMBER_LIMIT_IMPORTANT
Defines how many regular and/or important installation and
administration snapshot pairs to keep. Only the youngest snapshots will
be kept. Ignored if NUMBER_CLEANUP
is set to
"no"
.
The default value is "2-10"
for
NUMBER_LIMIT
and "4-10"
for
NUMBER_LIMIT_IMPORTANT
.
Example command to change or set:
tux >
sudo
snapper -c CONFIG set-config "NUMBER_LIMIT=10"
In case quota support is enabled (see
Section 7.7.5, “Adding Disk Quota Support”) the limit needs
to be specified as a minimum-maximum range, for example
2-10
. If quota support is disabled, a constant
value, for example 10
, needs to be provided,
otherwise cleaning-up will fail with an error.
NUMBER_MIN_AGE
Defines the minimum age in seconds a snapshot must have before it can automatically be deleted. Snapshots younger than the value specified here will not be deleted, regardless of how many exist.
The default value is "1800"
.
Example command to change or set:
tux >
sudo
snapper -c CONFIG set-config "NUMBER_MIN_AGE=864000"
NUMBER_LIMIT
, NUMBER_LIMIT_IMPORTANT
and NUMBER_MIN_AGE
are always evaluated. Snapshots are
only deleted when all conditions are met.
If you always want to keep the number of snapshots defined with
NUMBER_LIMIT*
regardless of their age, set
NUMBER_MIN_AGE
to 0
.
The following example shows a configuration to keep the last 10 important and regular snapshots regardless of age:
NUMBER_CLEANUP=yes NUMBER_LIMIT_IMPORTANT=10 NUMBER_LIMIT=10 NUMBER_MIN_AGE=0
On the other hand, if you do not want to keep snapshots beyond a certain
age, set NUMBER_LIMIT*
to 0
and
provide the age with NUMBER_MIN_AGE
.
The following example shows a configuration to only keep snapshots younger than ten days:
NUMBER_CLEANUP=yes NUMBER_LIMIT_IMPORTANT=0 NUMBER_LIMIT=0 NUMBER_MIN_AGE=864000
Cleaning up timeline snapshots is controlled by the following parameters of a Snapper configuration.
TIMELINE_CLEANUP
Enables or disables clean-up of timeline snapshots. If enabled,
snapshots are deleted when the total snapshot count exceeds a number
specified with TIMELINE_LIMIT_*
and an age specified with
TIMELINE_MIN_AGE
. Valid values:
yes
, no
.
The default value is "yes"
.
Example command to change or set:
tux >
sudo
snapper -c CONFIG set-config "TIMELINE_CLEANUP=yes"
TIMELINE_LIMIT_DAILY
,
TIMELINE_LIMIT_HOURLY
,
TIMELINE_LIMIT_MONTHLY
,
TIMELINE_LIMIT_WEEKLY
,
TIMELINE_LIMIT_YEARLY
Number of snapshots to keep for hour, day, month, week, and year.
The default value for each entry is "10"
, except for
TIMELINE_LIMIT_WEEKLY
, which is set to
"0"
by default.
TIMELINE_MIN_AGE
Defines the minimum age in seconds a snapshot must have before it can automatically be deleted.
The default value is "1800"
.
TIMELINE_CLEANUP="yes" TIMELINE_CREATE="yes" TIMELINE_LIMIT_DAILY="7" TIMELINE_LIMIT_HOURLY="24" TIMELINE_LIMIT_MONTHLY="12" TIMELINE_LIMIT_WEEKLY="4" TIMELINE_LIMIT_YEARLY="2" TIMELINE_MIN_AGE="1800"
This example configuration enables hourly snapshots which are
automatically cleaned up. TIMELINE_MIN_AGE
and
TIMELINE_LIMIT_*
are always both evaluated. In this
example, the minimum age of a snapshot before it can be deleted is set to
30 minutes (1800 seconds). Since we create hourly snapshots, this ensures
that only the latest snapshots are kept. If
TIMELINE_LIMIT_DAILY
is set to not zero, this means
that the first snapshot of the day is kept, too.
Hourly: The last 24 snapshots that have been made.
Daily: The first daily snapshot that has been made is kept from the last seven days.
Monthly: The first snapshot made on the last day of the month is kept for the last twelve months.
Weekly: The first snapshot made on the last day of the week is kept from the last four weeks.
Yearly: The first snapshot made on the last day of the year is kept for the last two years.
As explained in Section 7.1.1, “Types of Snapshots”, whenever you run a YaST module or execute Zypper, a pre snapshot is created on start-up and a post snapshot is created when exiting. In case you have not made any changes there will be no difference between the pre and post snapshots. Such “empty” snapshot pairs can be automatically be deleted by setting the following parameters in a Snapper configuration:
EMPTY_PRE_POST_CLEANUP
If set to yes
, pre and post snapshot pairs that do
not differ will be deleted.
The default value is "yes"
.
EMPTY_PRE_POST_MIN_AGE
Defines the minimum age in seconds a pre and post snapshot pair that does not differ must have before it can automatically be deleted.
The default value is "1800"
.
Snapper does not offer custom clean-up algorithms for manually created snapshots. However, you can assign the number or timeline clean-up algorithm to a manually created snapshot. If you do so, the snapshot will join the “clean-up queue” for the algorithm you specified. You can specify a clean-up algorithm when creating a snapshot, or by modifying an existing snapshot:
snapper create --description "Test" --cleanup-algorithm number
Creates a stand-alone snapshot (type single) for the default (root)
configuration and assigns the number
clean-up
algorithm.
snapper modify --cleanup-algorithm "timeline" 25
Modifies the snapshot with the number 25 and assigns the clean-up
algorithm timeline
.
In addition to the number and/or timeline clean-up algorithms described above, Snapper supports quotas. You can define what percentage of the available space snapshots are allowed to occupy. This percentage value always applies to the Btrfs subvolume defined in the respective Snapper configuration.
Btrfs quotas are applied to subvolumes, not to users. You may apply
disk space quotas to users and groups (for example, with the
quota
command) in addition to using Btrfs quotas.
If Snapper was enabled during the installation, quota support is
automatically enabled. In case you manually enable Snapper at a later point
in time, you can enable quota support by running snapper
setup-quota
. This requires a valid configuration (see
Section 7.5, “Creating and Modifying Snapper Configurations” for more information).
Quota support is controlled by the following parameters of a Snapper configuration.
QGROUP
The Btrfs quota group used by Snapper. If not set, run snapper
setup-quota
. If already set, only change if you are familiar
with man 8 btrfs-qgroup
. This value is set with
snapper setup-quota
and should not be changed.
SPACE_LIMIT
Limit of space snapshots are allowed to use in fractions of 1 (100%). Valid values range from 0 to 1 (0.1 = 10%, 0.2 = 20%, ...).
The following limitations and guidelines apply:
Quotas are only activated in addition to an existing number and/or timeline clean-up algorithm. If no clean-up algorithm is active, quota restrictions are not applied.
With quota support enabled, Snapper will perform two clean-up runs if required. The first run will apply the rules specified for number and timeline snapshots. Only if the quota is exceeded after this run, the quota-specific rules will be applied in a second run.
Even if quota support is enabled, Snapper will always keep the number of
snapshots specified with the NUMBER_LIMIT*
and
TIMELINE_LIMIT*
values, even if the quota will be
exceeded. It is therefore recommended to specify ranged values
(MIN-MAX
)
for NUMBER_LIMIT*
and
TIMELINE_LIMIT*
to ensure the quota can be applied.
If, for example, NUMBER_LIMIT=5-20
is set, Snapper
will perform a first clean-up run and reduce the number of regular
numbered snapshots to 20. In case these 20 snapshots exceed the
quota, Snapper will delete the oldest ones in a second run until the
quota is met. A minimum of five snapshots will always be kept, regardless
of the amount of space they occupy.
Snapshots share data, for efficient use of storage space, so using ordinary
commands like du
and df
won't measure
used disk space accurately. When you want to free up disk space on Btrfs
with quotas enabled, you need to know how much exclusive disk space is
used by each snapshot, rather than shared space. Snapper 0.6 and up reports
the used disk space for each snapshot in the
Used Space
column:
root #
snapper--iso list
# | Type | Pre # | Date | User | Used Space | Cleanup | Description | Userdata
----+--------+-------+---------------------+------+------------+---------+-----------------------+--------------
0 | single | | | root | | | current |
1* | single | | 2019-07-22 13:08:38 | root | 16.00 KiB | | first root filesystem |
2 | single | | 2019-07-22 14:21:05 | root | 14.23 MiB | number | after installation | important=yes
3 | pre | | 2019-07-22 14:26:03 | root | 144.00 KiB | number | zypp(zypper) | important=no
4 | post | 3 | 2019-07-22 14:26:04 | root | 112.00 KiB | number | | important=no
5 | pre | | 2019-07-23 08:19:36 | root | 128.00 KiB | number | zypp(zypper) | important=no
6 | post | 5 | 2019-07-23 08:19:43 | root | 80.00 KiB | number | | important=no
7 | pre | | 2019-07-23 08:20:50 | root | 256.00 KiB | number | yast sw_single |
8 | pre | | 2019-07-23 08:23:22 | root | 112.00 KiB | number | zypp(ruby.ruby2.5) | important=no
9 | post | 8 | 2019-07-23 08:23:35 | root | 64.00 KiB | number | | important=no
10 | post | 7 | 2019-07-23 08:24:05 | root | 16.00 KiB | number | |
The btrfs
command provides another view of space used by
snapshots:
root #
btrfs qgroup show -p /
qgroupid rfer excl parent
-------- ---- ---- ------
0/5 16.00KiB 16.00KiB ---
[...]
0/272 3.09GiB 14.23MiB 1/0
0/273 3.11GiB 144.00KiB 1/0
0/274 3.11GiB 112.00KiB 1/0
0/275 3.11GiB 128.00KiB 1/0
0/276 3.11GiB 80.00KiB 1/0
0/277 3.11GiB 256.00KiB 1/0
0/278 3.11GiB 112.00KiB 1/0
0/279 3.12GiB 64.00KiB 1/0
0/280 3.12GiB 16.00KiB 1/0
1/0 3.33GiB 222.95MiB ---
The qgroupid
column displays the identification number for
each subvolume, assigning a qgroup level/ID combination.
The rfer
column displays the total amount of data
referred to in the subvolume.
The excl
column displays the exclusive data in each
subvolume.
The parent
column shows the parent qgroup of the subvolumes.
The final item, 1/0
, shows the totals for the parent
qgroup. In the above example, 222.95 MiB will be freed if all subvolumes
are removed. Run the following command to see which snapshots are associated
with each subvolume:
root #
btrfs subvolume list -st /
ID gen top level path
-- --- --------- ----
267 298 266 @/.snapshots/1/snapshot
272 159 266 @/.snapshots/2/snapshot
273 170 266 @/.snapshots/3/snapshot
274 171 266 @/.snapshots/4/snapshot
275 287 266 @/.snapshots/5/snapshot
276 288 266 @/.snapshots/6/snapshot
277 292 266 @/.snapshots/7/snapshot
278 296 266 @/.snapshots/8/snapshot
279 297 266 @/.snapshots/9/snapshot
280 298 266 @/.snapshots/10/snapshot
Doing an upgrade from one service pack to another results in snapshots occupying a lot of disk space on the system subvolumes. Manually deleting these snapshots after they are no longer needed is recommended. See Section 7.6.4, “Deleting Snapshots” for details.
/var/log
,
/tmp
and other directories?
For some directories we decided to exclude them from snapshots. See Section 7.1.2, “Directories That Are Excluded from Snapshots” for a list and reasons. To exclude a path from snapshots we create a subvolume for that path.
Yes—refer to Section 7.3, “System Rollback by Booting from Snapshots” for details.
Currently Snapper does not offer means to prevent a snapshot from being
deleted manually. However, you can prevent snapshots from being
automatically deleted by clean-up algorithms. Manually created snapshots
(see Section 7.6.2, “Creating Snapshots”) have no clean-up
algorithm assigned unless you specify one with
--cleanup-algorithm
. Automatically created snapshots
always either have the number
or
timeline
algorithm assigned. To remove such an
assignment from one or more snapshots, proceed as follows:
List all available snapshots:
tux >
sudo
snapper list -a
Memorize the number of the snapshot(s) you want to prevent from being deleted.
Run the following command and replace the number placeholders with the number(s) you memorized:
tux >
sudo
snapper modify --cleanup-algorithm "" #1 #2 #n
Check the result by running snapper list -a
again.
The entry in the column Cleanup
should now be empty
for the snapshots you modified.
See the Snapper home page at http://snapper.io/.
This document describes the basic principles of the Kernel Live Patching (KLP) technology, and provides usage guidelines for the SLE Live Patching service.
KLP makes it possible to apply the latest security updates to Linux kernels without rebooting. This maximizes system uptime and availability, which is especially important for mission-critical systems.
The information provided in this document relates to the AMD64/Intel 64, POWER, and IBM Z architectures.
KLP offers several benefits.
Keeping a large numbers of servers automatically up-to-date is essential for organizations obtaining or maintaining certain compliance certifications. KLP can help achieve compliance, while reducing the need for costly maintenance windows.
Companies that work with service-level agreement contracts must guarantee a specific level of their system accessibility and uptime. Live patching makes it possible to patch systems without incurring downtime.
Since KLP is part of the standard system update mechanism, there is no need for specialized training or introduction of complicated maintenance routines.
Kernel live patches are delivered as packages with modified code that are separate from the main kernel package. The live patches are cumulative, so the latest patch contains all fixes from the previous ones for the kernel package. Each kernel live package is tied to the exact kernel revision for which it is issued. The live patch package version number increases with every addition of fixes.
Live patches contain only critical fixes, and they do not replace regular kernel updates that require a reboot. Consider live patches as temporary measures that protect the kernel until a proper kernel update and a reboot is performed.
The diagram below illustrates the overall relationship between live patches
and kernel updates. The list of CVEs and defect reports addressed by the
currently-active live patch can be viewed using the klp -v
patches
command.
It is possible to have multiple versions of the kernel package installed along with their live patches. These packages do not conflict. You can install updated kernel packages along with live patches for the running kernel. In this case, you may be prompted to reboot the system. Users with SLE Live Patching subscriptions are eligible for technical support as long as there are live patch updates for the running kernel (see Section 8.5.1, “Checking expiration date of the live patch”).
With KLP activated, every kernel update comes with a live patch package.
This live patch does not contain any fixes and serves as a seed for future
live patches for the corresponding kernel. These empty seed patches are
called initial patches
.
The scope of SLE Live Patching includes fixes for SUSE Common Vulnerability Scoring System (CVSS; SUSE CVSS is based on the CVSS v3.0 system) level 7+ vulnerabilities and bug fixes related to system stability or data corruption. However, it may not be technically feasible to create live patches for all fixes that fall under the specified categories. SUSE therefore reserves the right to skip fixes in situations where creating a kernel live patch is not possible for technical reasons. Currently, over 95% of qualifying fixes are released as live patches. For more information on CVSS (the base for the SUSE CVSS rating), see Common Vulnerability Scoring System SIG. .
KLP involves replacing functions and gracefully handling replacement of interdependent function sets. This is done by redirecting calls to old code to updated code in a different memory location. Changes in data structures make the situation more complicated, as the data remain in place and cannot be extended or reinterpreted. While there are techniques that allow indirect alteration of data structures, some fixes cannot be converted to live patches. In this situation, a system restart is the only way to apply the fixes.
To activate KLP on your system, you need to have active SLES and SLE Live Patching subscriptions. Visit SUSE Customer Center to check the status of your subscriptions and obtain an registration code for the SLE Live Patching subscription.
To activate Kernel Live Patching on your system, follow these steps:
Run the yast2 registration
command and click
.
Select
in the list of available extensions and click .Confirm the license terms and click
.Enter your SLE Live Patching registration code and click
.
Check the Live
Patching
and SLE Live Patching Lifecycle
Data
should be automatically selected for installation along
with additional packages to satisfy dependencies.
Click
to complete the installation. This will install the base Kernel Live Patching components on your system, the initial live patch, and the required dependencies.To activate Kernel Live Patching, you need to have an active SLES and SLES Live Patching subscriptions. Visit SUSE Customer Center to check the status of your subscriptions and obtain an registration code for the SLES Live Patching subscription.
Run sudo SUSEConnect --list-extensions
. Note the exact
activation command for SLES Live Patching. Example command output
(abbreviated):
$ SUSEConnect --list-extensions ... SUSE Linux Enterprise Live Patching 15 SP3 x86_64 Activate with: SUSEConnect -p sle-module-live-patching/15.3/x86_64 -r ADDITIONAL REGCODE
Activate SLES Live Patching using the obtained command followed by
-r
LIVE_PATCHING_REGISTRATION_CODE
, for
example:
SUSEConnect -p sle-module-live-patching/15.3/x86_64 -r LIVE_PATCHING_REGISTRATION_CODE
Install the required packages and dependencies using the command
zypper install -t pattern lp_sles
At this point, the system has already been live-patched.
Here is how the process works behind the scenes: When the package-installation system detects that there is an installed kernel that can be live-patched, and that there is a live patch for it in the software channel, the system selects the live patch for installation. The kernel then receives the live patch fixes as part of the package installation. The kernel gets live-patched even before the product installation is complete.
Kernel live-patches are installed as part of regular system updates. However, there are several things you should be aware of.
The kernel is live-patched if a kernel-livepatch-*
package has been installed for the running kernel. You can use the command
zypper se --details kernel-livepatch-*
to check what
kernel live-patch packages are installed on your system.
When kernel-default package is installed, the update manager prompts you to reboot the system. To prevent this message from apparing, you can filter out kernel updates from the patching operation. This can be done by adding package locks with Zypper. SUSE Manager also makes it possible to filter channel contents (see Live Patching with SUSE Manager).
You can check patching status using the klp status
command. To examine installed patches, run the klp -v
patches
command.
Keep in mind that while there may be multiple kernel packages installed on the system, only one of them is running at any given time. Similarly, there may be multiple live patch packages installed, but only one live patch is loaded into the kernel.
The active live patch is included in the initrd
. This means that in case of an
unexpected reboot, the system comes up with the live patch fixes applied,
so there is no need to perform patching again.
Make sure that the
lifecycle-data-sle-module-live-patching is installed,
then run the zypper lifecycle
command. You should see
expiration dates for live patches in the Package end of support if
different from product
section of the output.
Every live patch receives updates for one year from the release of the underlying kernel package. The Maintained kernels, patch updates and lifecycle page allows you to check expiration dates based on the running kernel version without installing the product extension.
Transactional updates are available in SUSE Linux Enterprise Desktop as a technology preview, for updating SLES when the root filesystem is read-only. Transactional updates are atomic (all updates are applied only if all updates succeed) and support rollbacks. It does not affect a running system as no changes are activated until after the system is rebooted. As reboots are disruptive, the admin must decide if a reboot is more expensive than disturbing running services. If reboots are too expensive then do not use transactional updates.
Transactional updates are run daily by the
transactional-update
script. The script checks for
available updates. If there are any updates, it creates a new snapshot of
the root file system in the background, and then fetches updates from the
release channels. After the new snapshot is completely updated, it is
marked as active and will be the new default root file system after the next
reboot of the system. When transactional-update
is set to run
automatically (which is the default behavior) it also reboots the system.
Both the time that the update runs and the reboot maintenance window are
configurable.
Only packages that are part of the snapshot of the root file system can be updated. If packages contain files that are not part of the snapshot, the update could fail or break the system.
RPMs that require a license to be accepted cannot be updated.
As a technical preview, there are certain limitations in functionality. The
following packages will not work with transactional-update
:
The nginx default index.html page may not be available
tomcat-webapps and tomcat-admin-webapps
phpMyAdmin
sca-appliance-*
mpi-selector
emacs works except for Emacs games
bind and bind-chrootenv
docbook*
sblim-sfcb*
texlive*
iso_ent
openjade
opensp
pcp
plymouth
postgresql-server-10
pulseaudio-gdm-hooks
smartmontools
The updater component of the system installer does not work with a read-only filesystem as it has no support for transactional updates.
Further considerations:
In general it is a good idea to minimize the time between updating the system and rebooting the machine.
Only one update can be applied at a time. Be sure to reboot after an update, and before the next update is applied.
update-alternatives
should not be run after a
transactional update until the machine has been rebooted.
Do not create new system users or system groups after a transactional update until after reboot. It is acceptable to create normal users and groups (UID > 1000, GID > 1000).
YaST is not yet aware of transactional updates. If a YaST module needs
to install additional packages, this will not work. Normal system
operations only modifying configuration files in /etc
will work.
For php7-fastcgi, you must manually create a symlink,
/srv/www/cgi-bin/php
, that points to
/usr/bin/php-cgi
.
ntpis part of the Legacy Module for migration from older SLES versions. It is not supported on a new SUSE Linux Enterprise Desktop installation, and has been replaced by chrony. If you continue to use ntp, a fresh installation is required to work correctly with transactional updates.
sblim-sfcb: The whole sblim ecosystem is incompatible with transactional update.
btrfs-defrag
from the
btrfsmaintenance package does not work with a read-only
root filesystem.
For btrfs-balance
, the variable
BTRFS_BALANCE_MOUNTPOINTS
in
/etc/sysconfig/btrfsmaintenance
must be changed from
/
to /.snapshots
.
For btrfs-scrub
, the variable
BTRFS_SCRUB_MOUNTPOINTS
in
/etc/sysconfig/btrfsmaintenance
must be changed from
/
to /.snapshots
.
You must enable the Transactional Server Module during system installation, and then select the Transactional Server System Role. Installing any package from the Transactional Server Module later in a running system is NOT supported and may break the system.
Note that changing the subvolume layout of the root partition, or putting
sub-directories or subvolumes of the root partition on their own partitions
(except /home
, /var
,
/srv
, and /opt
) is not supported,
and will most likely break the system.
Automatic updates are controlled by a systemd.timer
that runs once per day. This applies all updates, and informs
rebootmgrd
that the machine should be rebooted. You may
adjust the time when the update runs, see systemd.timer(5). To adjust the
maintenance window, which is when rebootmgrd
reboots the
system, see rebootmgrd(8).
You can disable automatic transactional updates with this command:
root #
systemctl --now disable transactional-update.timer
transactional-update
Command #Edit source
The transactional-update
command enables you to install
or remove updates of your system in an atomic way. Updates are applied only
if all of them can be successfully installed.
transactional-update
creates a snapshot of your system
before the update is applied, and you can restore this snapshot.
All changes become active only after reboot.
cleanup
If the current root filesystem is identical to the active root
filesystem (after a reboot, before transactional-update
creates a new snapshot with updates), all old snapshots without a
cleanup algorithm get a cleanup algorithm set. This ensures that old
snapshots will be deleted by Snapper. (See the section about cleanup
algorithms in snapper(8).) This also removes all unreferenced (and thus
unused) /etc
overlay directories in
/var/lib/overlay
:
root #
transactional-update cleanup
pkg in/install
Installs individual packages from the available channels using the
zypper install
command. This command can also be used
to install Program Temporary Fix (PTF) RPM files.
root #
transactional-update pkg install package_name
or
root #
transactional-update pkg install rpm1 rpm2
pkg rm/remove
Removes individual packages from the active snapshot using the
zypper remove
command. This command can also be used
to remove PTF RPM files.
root #
transactional-update pkg remove package_name
pkg up/update
Updates individual packages from the active snapshot using the
zypper update
command. Only packages that are part of
the snapshot of the base file system can be updated.
root #
transactional-update pkg remove package_name
up/update
If there are new updates available, a new snapshot is created and
zypper up/update
updates the snapshot.
root #
transactional-update up
dup
If there are new updates available, a new snapshot is created and
zypper dup –no-allow-vendor-change
updates the
snapshot. The snapshot is activated afterwards and becomes the new root
file system after reboot.
root #
transactional-update dup
patch
If there are new updates available, a new snapshot is created and
zypper patch
updates the snapshot.
root #
transactional-update patch
rollback
This sets the default subvolume. On systems with a read-write file system
snapper rollback
is called. On a read-only file system
and without any argument, the current system is set to a new default root
file system. If you specify a number, that snapshot is used as the
default root file system. On a read-only file system, it does not create
any additional snapshots.
root #
transactional-update rollback snapshot_number
grub.cfg
This creates a new GRUB2 configuration. Sometimes it is necessary to
adjust the boot configuration, for example adding additional kernel
parameters. Edit /etc/default/grub, run
transactional-update grub.cfg
, and then reboot to
activate the change. You must immediately reboot, or the new GRUB2
configuration will be overwritten with the default by the next
transactional-update.
root #
transactional-update grub.cfg
reboot
This parameter triggers a reboot after the action is completed.
root #
transactional-update dup reboot
--help
This prints a help screen with options and subcommands.
root #
transactional-update --help
If the upgrade fails, run supportconfig
to collect log
data. Provide the resulting files, including
/var/log/transactional-update.log
to SUSE Support.
Virtual Network Computing (VNC) enables you to access a remote computer via a graphical desktop, and run remote graphical applications. VNC is platform-independent and accesses the remote machine from any operating system. This chapter describes how to connect to a VNC server with the desktop clients vncviewer and Remmina, and how to operate a VNC server.
SUSE Linux Enterprise Desktop supports two different kinds of VNC sessions: One-time sessions that “live” as long as the VNC connection from the client is kept up, and persistent sessions that “live” until they are explicitly terminated.
A VNC server can offer both kinds of sessions simultaneously on different ports, but an open session cannot be converted from one type to the other.
vncviewer
Client #Edit source
To connect to a VNC service provided by a server, a client is needed. The
default in SUSE Linux Enterprise Desktop is vncviewer
, provided by the
tigervnc
package.
To start your VNC viewer and initiate a session with the server, use the command:
tux >
vncviewer jupiter.example.com:1
Instead of the VNC display number you can also specify the port number with two colons:
tux >
vncviewer jupiter.example.com::5901
The actual display or port number you specify in the VNC client must be
the same as the display or port number picked by the
vncserver
command on the target machine. See
Section 10.4, “Configuring Persistent VNC Server Sessions” for further info.
By running vncviewer
without specifying
--listen
or a host to connect to, it will show a window
to ask for connection details. Enter the host into the field like in Section 10.1.1, “Connecting Using the vncviewer CLI”
and click .
The VNC protocol supports different kinds of encrypted connections, not to be confused with password authentication. If a connection does not use TLS, the text “(Connection not encrypted!)” can be seen in the window title of the VNC viewer.
Remmina is a modern and feature rich remote desktop client. It supports several access methods, for example VNC, SSH, RDP, and Spice.
To use Remmina, verify whether the remmina package is installed on your system, and install it if not. Remember to install the VNC plug-in for Remmina as well:
root #
zypper in remmina remmina-plugin-vnc
Run Remmina by entering the remmina
command.
The main application window shows the list of stored remote sessions. Here you can add and save a new remote session, quick-start a new session without saving it, start a previously saved session, or set Remmina's global preferences.
To add and save a new remote session, click in the
top left of the main window. The
window opens.
Complete the fields that specify your newly added remote session profile. The most important are:
Name of the profile. It will be listed in the main window.
The protocol to use when connecting to the remote session, for example VNC.
The IP or DNS address and display number of the remote server.
Credentials to use for remote authentication. Leave empty for no authentication.
Select the best options according to your connection speed and quality.
Select the
tab to enter more specific settings.If the communication between the client and the remote server is not encrypted, activate
, otherwise the connection fails.Select the
tab for advanced SSH tunneling and authentication options.Confirm with
. Your new profile will be listed in the main window.You can either start a previously saved session, or quick-start a remote session without saving the connection details.
To start a remote session quickly without adding and saving connection details, use the drop-down box and text box at the top of the main window.
Select the communication protocol from the drop-down box, for example 'VNC', then enter the VNC server DNS or IP address followed by a colon and a display number, and confirm with Enter.
To open a specific remote session, double-click it from the list of sessions.
Remote sessions are opened in tabs of a separate window. Each tab hosts one session. The toolbar on the left of the window helps you manage the windows/sessions, such as toggle fullscreen mode, resize the window to match the display size of the session, send specific keystrokes to the session, take screenshots of the session, or set the image quality.
To edit a saved remote session, right-click its name in Remmina's main window and select . Refer to Section 10.2.3, “Adding Remote Sessions” for the description of the relevant fields.
To copy a saved remote session, right-click its name in Remmina's main window and select . In the window, change the name of the profile, optionally adjust relevant options, and confirm with .
To Delete a saved remote session, right-click its name in Remmina's main window and select . Confirm with in the next dialog.
If you need to open a remote session from the command line or from a batch file without first opening the main application window, use the following syntax:
tux >
remmina -c profile_name.remmina
Remmina's profile files are stored in the
.local/share/remmina/
directory in your home
directory. To determine which profile file belongs to the session you want
to open, run Remmina, click the session name in the main window, and read
the path to the profile file in the window's status line at the bottom.
While Remmina is not running, you can rename the profile file to a more
reasonable file name, such as sle15.remmina
. You can
even copy the profile file to your custom directory and run it using the
remmina -c
command from there.
A one-time session is initiated by the remote client. It starts a graphical login screen on the server. This way you can choose the user which starts the session and, if supported by the login manager, the desktop environment. When you terminate the client connection to such a VNC session, all applications started within that session will be terminated, too. One-time VNC sessions cannot be shared, but it is possible to have multiple sessions on a single host at the same time.
Start
› › .Check
.Activate
if you plan to access the VNC session in a Web browser window.If necessary, also check
(for example, when your network interface is configured to be in the External Zone). If you have more than one network interface, restrict opening the firewall ports to a specific interface via .Confirm your settings with
.In case not all needed packages are available yet, you need to approve the installation of missing packages.
YaST makes changes to the display manager settings. You need to log out of your current graphical session and restart the display manager for the changes to take effect.
The default configuration on SUSE Linux Enterprise Desktop serves sessions with a
resolution of 1024x768 pixels at a color depth of 16-bit. The sessions are
available on ports 5901
for
“regular” VNC viewers (equivalent to VNC display
1
) and on port
5801
for Web browsers.
Other configurations can be made available on different ports. Ask your system administrator for details if you need to modify the configuration.
VNC display numbers and X display numbers are independent in one-time sessions. A VNC display number is manually assigned to every configuration that the server supports (:1 in the example above). Whenever a VNC session is initiated with one of the configurations, it automatically gets a free X display number.
By default, both the VNC client and server try to communicate securely via a self-signed SSL certificate, which is generated after installation. You can either use the default one, or replace it with your own. When using the self-signed certificate, you need to confirm its signature before the first connection—both in the VNC viewer and the Web browser.
To connect to a one-time VNC session, a VNC viewer must be installed, see
also Section 10.1, “The vncviewer
Client”. Alternatively use a
JavaScript-capable Web browser to view the VNC session by entering the
following URL: http://jupiter.example.com:5801
You can skip this section, if you do not need or want to modify the default configuration.
One-time VNC sessions are started via the systemd
socket
xvnc.socket
. By default it offers six
configuration blocks: three for VNC viewers (vnc1
to
vnc3
), and three serving a JavaScript client
(vnchttpd1
to vnchttpd3
). By default
only vnc1
and vnchttpd1
are active.
To activate the VNC server socket at boot time, run the following command:
tux >
sudo
systemctl enable xvnc.socket
To start the socket immediately, run:
tux >
sudo
systemctl start xvnc.socket
The Xvnc
server can be configured via the
server_args
option. For a list of options, see
Xvnc --help
.
When adding custom configurations, make sure they are not using ports that are already in use by other configurations, other services, or existing persistent VNC sessions on the same host.
Activate configuration changes by entering the following command:
tux >
sudo
systemctl reload xvnc.socket
When activating Remote Administration as described in
Procedure 10.1, “Enabling One-time VNC Sessions”, the ports
5801
and
5901
are opened in the firewall.
If the network interface serving the VNC sessions is protected by a
firewall, you need to manually open the respective ports when activating
additional ports for VNC sessions. See
Book “Security and Hardening Guide”, Chapter 23 “Masquerading and Firewalls” for instructions.
A persistent session can be accessed from multiple clients simultaneously. This is ideal for demonstration purposes where one client has full access and all other clients have view-only access. Another use case are trainings where the trainer might need access to the trainee's desktop.
To connect to a persistent VNC session, a VNC viewer must be installed.
Refer to Section 10.1, “The vncviewer
Client” for more details. Alternatively
use a JavaScript-capable Web browser to view the VNC session by entering the
following URL: http://jupiter.example.com:5801
There are two types of persistent VNC sessions:
vncserver
#Edit sourceThis type of persistent VNC session is initiated on the server. The session and all applications started in this session run regardless of client connections until the session is terminated. Access to persistent sessions is protected by two possible types of passwords:
a regular password that grants full access or
an optional view-only password that grants a non-interactive (view-only) access.
A session can have multiple client connections of both kinds at once.
vncserver
#Open a shell and make sure you are logged in as the user that should own the VNC session.
If the network interface serving the VNC sessions is protected by a firewall, you need to manually open the port used by your session in the firewall. If starting multiple sessions you may alternatively open a range of ports. See Book “Security and Hardening Guide”, Chapter 23 “Masquerading and Firewalls” for details on how to configure the firewall.
vncserver
uses the ports
5901
for display
:1
, 5902
for
display :2
, and so on. For persistent sessions, the
VNC display and the X display usually have the same number.
To start a session with a resolution of 1024x768 pixel and with a color depth of 16-bit, enter the following command:
vncserver -alwaysshared -geometry 1024x768 -depth 16
The vncserver
command picks an unused display number
when none is given and prints its choice. See man 1
vncserver
for more options.
When running vncserver
for the first time, it asks for a
password for full access to the session. If needed, you can also provide a
password for view-only access to the session.
The password(s) you are providing here are also used for future sessions
started by the same user. They can be changed with the
vncpasswd
command.
Make sure to use strong passwords of significant length (eight or more characters). Do not share these passwords.
To terminate the session shut down the desktop environment that runs inside the VNC session from the VNC viewer as you would shut it down if it was a regular local X session.
If you prefer to manually terminate a session, open a shell on the VNC
server and make sure you are logged in as the user that owns the VNC
session you want to terminate. Run the following command to terminate the
session that runs on display :1
: vncserver
-kill :1
Persistent VNC sessions can be configured by editing
$HOME/.vnc/xstartup
. By default this shell script
starts the same GUI/window manager it was started from. In SUSE Linux Enterprise Desktop
this will either be GNOME or IceWM. If you want to start your session
with a window manager of your choice, set the variable
WINDOWMANAGER
:
WINDOWMANAGER=gnome vncserver -geometry 1024x768 WINDOWMANAGER=icewm vncserver -geometry 1024x768
Persistent VNC sessions are configured in a single per-user configuration. Multiple sessions started by the same user will all use the same start-up and password files.
vncmanager
#Edit sourceStart
› › .Activate
.Activate
if you plan to access the VNC session in a Web browser window.If necessary, also check
(for example, when your network interface is configured to be in the External Zone). If you have more than one network interface, restrict opening the firewall ports to a specific interface via .Confirm your settings with
.In case not all needed packages are available yet, you need to approve the installation of missing packages.
YaST makes changes to the display manager settings. You need to log out of your current graphical session and restart the display manager for the changes to take effect.
After you enable the VNC session management as described in Procedure 10.3, “Enabling Persistent VNC Sessions”, you can normally connect to
the remote session with your favorite VNC viewer, such as
vncviewer
or Remmina. You will be presented with the
login screen. After you log in, the 'VNC' icon will appear in the system
tray of your desktop environment. Click the icon to open the window. If it does not appear or if your desktop
environment does not support icons in the system tray, run
vncmanager-controller
manually.
There are several settings that influence the VNC session's behavior:
This is equivalent to a one-time session. It is not visible to others and will be terminated after you disconnect from it. Refer to Section 10.3, “Configuring One-time Sessions on the VNC Server” for more information.
The session is visible to other users and keeps running even after you disconnect from it.
Here you can specify the name of the persistent session so that it is easily identified when reconnecting.
The session will be freely accessible without having to log in under user credentials.
You need to log in with a valid user name and password to access the session. Lists the valid user names in the
text box.Prevents multiple users from joining the session at the same time.
Allows multiple users to join the persistent session at the same time. Useful for remote presentations or trainings.
Confirm with
.After you set up a persistent VNC session as described in Section 10.4.2.1, “Configuring Persistent VNC Sessions”, you can join it with your VNC viewer. After your VNC client connects to the server, you will be prompted to choose whether you want to create a new session, or join the existing one:
After you click the name of the existing session, you may be asked for login credentials, depending on the persistent session settings.
If the VNC server is set up properly, all communication between the VNC server and the client is encrypted. The authentication happens at the beginning of the session; the actual data transfer only begins afterward.
Whether for a one-time or a persistent VNC session, security options are
configured via the -securitytypes
parameter of the
/usr/bin/Xvnc
command located on the
server_args
line. The -securitytypes
parameter selects both authentication method and encryption. It has the
following options:
No authentication.
Authentication using custom password.
Authentication using PAM to verify user's password.
No encryption.
Anonymous TLS encryption. Everything is encrypted, but there is no verification of the remote host. So you are protected against passive attackers, but not against man-in-the-middle attackers.
TLS encryption with certificate. If you use a self-signed certificate, you will be asked to verify it on the first connection. On subsequent connections you will be warned only if the certificate changed. So you are protected against everything except man-in-the-middle on the first connection (similar to typical SSH usage). If you use a certificate signed by a certificate authority matching the machine name, then you get full security (similar to typical HTTPS usage).
With X509 based encryption, you need to specify the path to the X509
certificate and the key with -X509Cert
and
-X509Key
options.
If you select multiple security types separated by comma, the first one supported and allowed by both client and server will be used. That way you can configure opportunistic encryption on the server. This is useful if you need to support VNC clients that do not support encryption.
On the client, you can also specify the allowed security types to prevent a downgrade attack if you are connecting to a server which you know has encryption enabled (although our vncviewer will warn you with the "Connection not encrypted!" message in that case).
Today, a typical user has several computers: home and workplace machines, a laptop, a smartphone or a tablet. This makes the task of keeping files and documents in synchronization across multiple devices all the more important.
Before you start using a synchronization tool, you should familiarize yourself with its features and functionality. Make sure to back up your important files.
For synchronizing a large amount of data over a slow network connection, Rsync offers a reliable method of transmitting only changes within files. This applies not only to text files but also binary files. To detect the differences between files, Rsync subdivides the files into blocks and computes check sums over them.
Detecting changes requires some computing power. So make sure that machines on both ends have enough resources, including RAM.
Rsync can be particularly useful when large amounts of data containing only minor changes need to be transmitted regularly. This is often the case when working with backups. Rsync can also be useful for mirroring staging servers that store complete directory trees of Web servers to a Web server in a DMZ.
Despite its name, Rsync is not a synchronization tool. Rsync is a tool that copies data only in one direction at a time. It does not and cannot do the reverse. If you need a bidirectional tool which can synchronize both source and destination, use Csync.
Rsync is a command-line tool that has the following basic syntax:
rsync [OPTION] SOURCE [SOURCE]... DEST
You can use Rsync on any local or remote machine, provided you have access and write permissions. It is possible to have multiple SOURCE entries. The SOURCE and DEST placeholders can be paths, URLs, or both.
Below are the most common Rsync options:
-v
Outputs more verbose text
-a
Archive mode; copies files recursively and preserves time stamps, user/group ownership, file permissions, and symbolic links
-z
Compresses the transmitted data
When working with Rsync, you should pay particular attention to trailing slashes. A trailing slash after the directory denotes the content of the directory. No trailing slash denotes the directory itself.
The following description assumes that the current user has write
permissions to the directory /var/backup
. To copy a
single file from one directory on your machine to another path, use the
following command:
tux >
rsync
-avz backup.tar.xz /var/backup/
The file backup.tar.xz
is copied to
/var/backup/
; the absolute path will be
/var/backup/backup.tar.xz
.
Do not forget to add the trailing slash after the
/var/backup/
directory! If you do not insert the slash,
the file backup.tar.xz
is copied to
/var/backup
(file) not inside the
directory /var/backup/
!
Copying a directory is similar to copying a single file. The following
example copies the directory tux/
and
its content into the directory /var/backup/
:
tux >
rsync
-avz tux /var/backup/
Find the copy in the absolute path
/var/backup/tux/
.
The Rsync tool is required on both machines. To copy files from or to remote directories requires an IP address or a domain name. A user name is optional if your current user names on the local and remote machine are the same.
To copy the file file.tar.xz
from your local host to
the remote host
192.168.1.1
with
same users (being local and remote), use the following command:
tux >
rsync
-avz file.tar.xz tux@192.168.1.1:
Depending on what you prefer, these commands are also possible and equivalent:
tux >
rsync
-avz file.tar.xz 192.168.1.1:~tux >
rsync
-avz file.tar.xz 192.168.1.1:/home/tux
In all cases with standard configuration, you will be prompted to enter your
passphrase of the remote user. This command will copy
file.tar.xz
to the home directory of user tux
(usually /home/tux
).
Copying a directory remotely is similar to copying a directory locally. The
following example copies the directory
tux/
and its content into the remote
directory /var/backup/
on the
192.168.1.1
host:
tux >
rsync
-avz tux 192.168.1.1:/var/backup/
Assuming you have write permissions on the host
192.168.1.1
, you will
find the copy in the absolute path
/var/backup/tux
.
Rsync can run as a daemon
(rsyncd
) listening on default
port 873 for incoming connections. This daemon can receive “copying
targets”.
The following description explains how to create an Rsync server on
jupiter
with a backup target.
This target can be used to store your backups. To create an Rsync server, do
the following:
On jupiter, create a directory to store all your backup files. In this
example, we use /var/backup
:
root #
mkdir
/var/backup
Specify ownership. In this case, the directory is owned by user
tux
in group
users
:
root #
chown
tux.users /var/backup
Configure the rsyncd daemon.
We will separate the configuration file into a main file and some
“modules” which hold your backup target. This makes it easier
to add additional targets later. Global values can be stored in
/etc/rsyncd.d/*.inc
files, whereas your modules are
placed in /etc/rsyncd.d/*.conf
files:
Create a directory /etc/rsyncd.d/
:
root #
mkdir
/etc/rsyncd.d/
In the main configuration file /etc/rsyncd.conf
,
add the following lines:
# rsyncd.conf main configuration file log file = /var/log/rsync.log pid file = /var/lock/rsync.lock &merge /etc/rsyncd.d 1 &include /etc/rsyncd.d 2
Create your module (your backup target) in the file
/etc/rsyncd.d/backup.conf
with the following lines:
# backup.conf: backup module [backup] 1 uid = tux 2 gid = users 2 path = /var/backup 3 auth users = tux 4 secrets file = /etc/rsyncd.secrets 5 comment = Our backup target
The backup target. You can use any name you like.
However, it is a good idea to name a target according to its purpose
and use the same name in your | |
Specifies the user name or group name that is used when the file transfer takes place. | |
Defines the path to store your backups (from Step 1). | |
Specifies a comma-separated list of allowed users. In its simplest
form, it contains the user names that are allowed to connect to this
module. In our case, only user | |
Specifies the path of a file that contains lines with user names and plain passwords. |
Create the /etc/rsyncd.secrets
file with the
following content and replace PASSPHRASE:
# user:passwd tux:PASSPHRASE
Make sure the file is only readable by root
:
root #
chmod
0600 /etc/rsyncd.secrets
Start and enable the rsyncd daemon with:
root #
systemctl
enable rsyncdroot #
systemctl
start rsyncd
Test the access to your Rsync server:
tux >
rsync
jupiter::
You should see a response that looks like this:
backup Our backup target
Otherwise, check your configuration file, firewall and network settings.
The above steps create an Rsync server that can now be used to store
backups. The example also creates a log file listing all connections. This
file is stored in /var/log/rsyncd.log
. This is useful
if you want to debug your transfers.
To list the content of your backup target, use the following command:
tux >
rsync -avz jupiter::backup
This command lists all files present in the directory
/var/backup
on the server. This request is also logged
in the log file /var/log/rsyncd.log
. To start an actual
transfer, provide a source directory. Use .
for the
current directory. For example, the following command copies the current
directory to your Rsync backup server:
tux >
rsync -avz . jupiter::backup
By default, Rsync does not delete files and directories when it runs. To
enable deletion, the additional option --delete
must be
stated. To ensure that no newer files are deleted, the option
--update
can be used instead. Any conflicts that arise must
be resolved manually.
Bidirectional file synchronizer, see https://csync.org/.
Creates incremental backups, see https://rsnapshot.org.
A file synchronizer similar to CSync but with a graphical interface, see https://www.seas.upenn.edu/~bcpierce/unison/.
A disaster recovery framework, see the Administration Guide of the SUSE Linux Enterprise High Availability Extension https://documentation.suse.com/sle-ha/.
Booting a Linux system involves different components and tasks. After a
firmware and hardware initialization process, which depends on the
machine's architecture, the kernel is started by means of the boot loader
GRUB 2. After this point, the boot process is completely controlled by the
operating system and handled by systemd
. systemd
provides a set of
“targets” that boot configurations for everyday usage,
maintenance or emergencies.
UEFI (Unified Extensible Firmware Interface) is the interface between the firmware that comes with the system hardware, all the hardware components of the system, and the operating system.
This chapter describes how to configure GRUB 2, the boot loader used in SUSE® Linux Enterprise Desktop. It is the successor to the traditional GRUB boot loader—now called “GRUB Legacy”. GRUB 2 has been the default boot loader in SUSE® Linux Enterprise Desktop since version 12. A YaST module is available for configuring the most important settings. The boot procedure as a whole is outlined in Chapter 12, Introduction to the Boot Process. For details on Secure Boot support for UEFI machines, see Chapter 13, UEFI (Unified Extensible Firmware Interface).
systemd
DaemonThe program systemd is the process with process ID 1. It is responsible for initializing the system in the required way. systemd is started directly by the kernel and resists signal 9, which normally terminates processes. All other programs are either started directly by systemd or by one of its chi…
Booting a Linux system involves different components and tasks. After a
firmware and hardware initialization process, which depends on the
machine's architecture, the kernel is started by means of the boot loader
GRUB 2. After this point, the boot process is completely controlled by the
operating system and handled by systemd
. systemd
provides a set of
“targets” that boot configurations for everyday usage,
maintenance or emergencies.
This chapter uses terms that can be interpreted ambiguously. To understand how they are used here, read the definitions below:
init
Two different processes are commonly named “init”:
The initramfs
process mounting the root
file system
The operating system process that starts all other processes that is executed from the real root file system
In both cases, the systemd
program is taking care of this task. It is
first executed from the initramfs
to mount the
root file system. Once that has succeeded, it is re-executed from the
root file system as the initial process. To avoid confusing these two
systemd
processes, we refer to the first process as init on
initramfs and to the second one as
systemd.
initrd
/initramfs
An initrd
(initial RAM disk) is an image file
containing a root file system image which is loaded by the kernel and
mounted from /dev/ram
as the temporary root file
system. Mounting this file system requires a file system driver.
Beginning with kernel 2.6.13, the initrd has been replaced by the
initramfs
(initial RAM file system), which does
not require a file system driver to be mounted. SUSE Linux Enterprise Desktop exclusively
uses an initramfs
. However, since the
initramfs
is stored as
/boot/initrd
, it is often called
“initrd”. In this chapter we exclusively use the name
initramfs
.
The Linux boot process consists of several stages, each represented by a different component:
During the initialization phase the machine's hardware is set up and the devices are prepared. This process differs significantly between hardware architectures.
SUSE Linux Enterprise Desktop uses the boot loader GRUB 2 on all architectures. Depending on the architecture and firmware, starting the GRUB 2 boot loader can be a multi-step process. The purpose of the boot loader is to load the kernel and the initial, RAM-based file system (initramfs). For more information about GRUB 2, refer to Chapter 14, The Boot Loader GRUB 2.
After turning on the computer, the BIOS or the UEFI initializes the screen and keyboard, and tests the main memory. Up to this stage, the machine does not access any mass storage media. Subsequently, the information about the current date, time, and the most important peripherals are loaded from the CMOS values. When the boot media and its geometry are recognized, the system control passes from the BIOS/UEFI to the boot loader.
On a machine equipped with a traditional BIOS, only code from the first
physical 512-byte data sector (the Master Boot Record, MBR) of the boot
disk can be loaded. Only a minimal GRUB 2 fits into the MBR. Its sole
purpose is to load a GRUB 2 core image containing file system drivers from
the gap between the MBR and the first partition (MBR partition table) or
from the BIOS boot partition (GPT partition table). This image contains
file system drivers and therefore is able to access
/boot
located on the root file
system. /boot
contains additional modules for GRUB 2
core as well as the kernel and the initramfs image. Once it has access to
this partition, GRUB 2 loads the kernel and the initramfs image into
memory and hands control over to the kernel.
When booting a BIOS system from an encrypted file system that includes an
encrypted /boot
partition, you need to enter the
password for decryption twice. It is first needed by GRUB 2 to decrypt
/boot
and then for systemd
to mount the encrypted
volumes.
On machines with UEFI the boot process is much simpler than on machines
with a traditional BIOS. The firmware is able to read from a FAT formatted
system partition of disks with a GPT partition table. This EFI
system-partition (in the running system mounted as
/boot/efi
) holds enough space to host a fully-fledged
GRUB 2 which is directly loaded and executed by the firmware.
If the BIOS/UEFI supports network booting, it is also possible to configure a boot server that provides the boot loader. The system can then be booted via PXE. The BIOS/UEFI acts as the boot loader. It gets the boot image from the boot server and starts the system. This is completely independent of local hard disks.
On IBM Z the boot process must be initialized by a boot loader
called zipl
(z initial program load). Although
zipl
supports reading from various file systems, it
does not support the SLE default file system (Btrfs) or booting from
snapshots. SUSE Linux Enterprise Desktop therefore uses a two-stage boot process that
ensures full Btrfs support at boot-time:
zipl
boots from the partition
/boot/zipl
that can be formatted with the Ext2,
Ext3, Ext4, or XFS file system. This partition contains a minimal kernel
and an initramfs that are loaded into memory. The initramfs contains a
Btrfs driver (among others) and the boot loader GRUB 2. The kernel is
started with a parameter initgrub
, which tells it to
start GRUB 2.
The kernel mounts the root file system, so /boot
becomes accessible. Now GRUB 2 is started from the initramfs. It reads
its configuration from /boot/grub2/grub.cfg
and
loads the final kernel and initramfs from
/boot
. The new kernel now gets loaded via Kexec.
When the boot loader has passed on system control, the boot process is the
same on all architectures. The boot loader loads both the kernel and an
initial RAM-based file system (initramfs
) into
memory and the kernel takes over.
After the kernel has set up memory management and has detected the CPU type
and its features, it initializes the hardware and mounts the temporary root
file system from the memory that was loaded with the
initramfs
.
initramfs
file #Edit source
initramfs
(initial RAM file system) is a small
cpio archive that the kernel can load into a RAM disk. It is located at
/boot/initrd
. It can be created with a tool called
dracut
—refer to man 8 dracut
for details.
The initramfs
provides a minimal Linux
environment that enables the execution of programs before the actual root
file system is mounted. This minimal Linux environment is loaded into
memory by BIOS or UEFI routines and does not have specific hardware
requirements other than sufficient memory. The
initramfs
archive must always provide an
executable named init
that executes the systemd
daemon on the root file system for the boot process to proceed.
Before the root file system can be mounted and the operating system can be
started, the kernel needs the corresponding drivers to access the device
on which the root file system is located. These drivers may include
special drivers for certain kinds of hard disks or even network drivers to
access a network file system. The needed modules for the root file system
are loaded by init
on
initramfs
. After the modules are loaded,
udev
provides the
initramfs
with the needed devices. Later in the
boot process, after changing the root file system, it is necessary to
regenerate the devices. This is done by the systemd
unit
systemd-udev-trigger.service
.
Because the initramfs
contains drivers, it needs
to be updated whenever a new version of one of its drivers is
available. This is done automatically when installing the package
containing the driver update. YaST or zypper will inform you about
this by showing the output of the command that generates the
initramfs
. However, there are some occasions
when you need to regenerate an initramfs
manually:
If you need to change hardware (for example, hard disks), and this
hardware requires different drivers to be in the kernel at boot time,
you must update the initramfs
file.
Open or create
/etc/dracut.conf.d/10-DRIVER.conf
and add the following line (mind the leading whitespace):
force_drivers+=" DRIVER1 "
Replace DRIVER1 with the module name of the driver. If you need to add more than one driver, list them space-separated:
force_drivers+=" DRIVER1 DRIVER2 "
Proceed with Procedure 12.1, “Generate an initramfs”.
Whenever you move swap files, or system directories like
/usr
in a running system to a RAID or logical
volume, you need to create an initramfs
that
contains support for software RAID or LVM drivers.
To do so, create the respective entries in
/etc/fstab
and mount the new entries (for example
with mount -a
and/or swapon -a
).
Proceed with Procedure 12.1, “Generate an initramfs”.
Whenever you add (or remove) a disk to a logical volume group
or a Btrfs RAID containing the root file system, you need to create an
initramfs
that contains support for the
enlarged volume. Follow the instructions at Procedure 12.1, “Generate an initramfs”.
Proceed with Procedure 12.1, “Generate an initramfs”.
If you change the values of kernel variables via the
sysctl
interface by editing related files
(/etc/sysctl.conf
or
/etc/sysctl.d/*.conf
), the change will be lost on
the next system reboot. Even if you load the values with sysctl
--system
at runtime, the changes are not saved into the
initramfs
file. You need to update it by
proceeding as outlined in Procedure 12.1, “Generate an initramfs”.
Note that all commands in the following procedure need to be executed
as the root
user.
Enter your /boot
directory:
root #
cd /boot
Generate a new initramfs
file with
dracut
, replacing
MY_INITRAMFS with a file name of
your choice:
root #
dracut MY_INITRAMFS
Alternatively, run dracut -f
FILENAME
to replace an existing init file.
(Skip this step if you ran dracut -f
in the previous
step.) Create a symlink from the initramfs
file you created in the previous step to initrd
:
root #
ln -sf MY_INITRAMFSinitrd
On the IBM Z architecture, additionally run
grub2-install
.
The temporary root file system mounted by the kernel from the
initramfs
contains the executable systemd
(which
is called init
on
initramfs
in the following, also see Section 12.1, “Terminology”. This program performs all actions needed
to mount the proper root file system. It provides kernel functionality for
the needed file system and device drivers for mass storage controllers with
udev
.
The main purpose of init
on
initramfs
is to prepare the mounting of and access
to the real root file system. Depending on your system configuration,
init
on initramfs
is
responsible for the following tasks.
Depending on your hardware configuration, special drivers may be needed to access the hardware components of your computer (the most important component being your hard disk). To access the final root file system, the kernel needs to load the proper file system drivers.
The kernel generates device events depending on loaded modules.
udev
handles these events and
generates the required special block files on a RAM file system in
/dev
. Without those special files, the file system
and other devices would not be accessible.
If you configured your system to hold the root file system under RAID or
LVM, init
on initramfs
sets up LVM or RAID to enable access to the root file system later.
If you configured your system to use a network-mounted root file system
(mounted via NFS), init
must make sure that the
proper network drivers are loaded and that they are set up to allow
access to the root file system.
If the file system resides on a network block device like iSCSI or SAN,
the connection to the storage server is also set up by
init
on initramfs
.
SUSE Linux Enterprise Desktop supports booting from a secondary iSCSI target if the
primary target is not available. .
If the root file system fails to mount from within the boot environment, it must be checked and repaired before the boot can continue. The file system checker will be automatically started for Ext3 and Ext4 file systems. The repair process is not automated for XFS and Btrfs file systems, and the user is presented with information describing the options available to repair the file system. When the file system has been successfully repaired, exiting the boot environment will cause the system to retry mounting the root file system. If successful, the boot will continue normally.
When init
on initramfs
is called during the initial boot as part of the installation process, its
tasks differ from those mentioned above. Note that the installation system
also does not start systemd
from
initramfs
—these tasks are performed by
linuxrc
.
When starting the installation process, your machine loads an
installation kernel and a special init
containing the YaST installer. The YaST installer is running in a
RAM file system and needs to have information about the location of the
installation medium to access it for installing the operating system.
As mentioned in Section 12.2.2.1, “The initramfs
file”, the boot process
starts with a minimum set of drivers that can be used with most
hardware configurations. On AArch64, POWER, and AMD64/Intel 64 machines,
linuxrc
starts an initial hardware scanning process
that determines the set of drivers suitable for your hardware
configuration. On IBM Z, a list of drivers and their parameters
needs to be provided, for example via linuxrc or a parmfile.
These drivers are used to generate a custom
initramfs
that is needed to boot the
system. If the modules are not needed for boot but for coldplug, the
modules can be loaded with systemd
; for more information, see Section 15.6.4, “Loading Kernel Modules”.
When the hardware is properly recognized, the appropriate drivers are
loaded. The udev
program
creates the special device files and linuxrc
starts the installation system with the YaST installer.
Finally, linuxrc
starts YaST, which starts
the package installation and the system configuration.
After the “real” root file system has been found, it is
checked for errors and mounted. If this is successful, the
initramfs
is cleaned and the systemd
daemon on
the root file system is executed. systemd
is Linux's system and service
manager. It is the parent process that is started as PID 1 and acts as an
init system which brings up and maintains user space services. See Chapter 15, The systemd
Daemon for details.
UEFI (Unified Extensible Firmware Interface) is the interface between the firmware that comes with the system hardware, all the hardware components of the system, and the operating system.
UEFI is becoming more and more available on PC systems and thus is replacing the traditional PC-BIOS. UEFI, for example, properly supports 64-bit systems and offers secure booting (“Secure Boot”, firmware version 2.3.1c or better required), which is one of its most important features. Lastly, with UEFI a standard firmware will become available on all x86 platforms.
UEFI additionally offers the following advantages:
Booting from large disks (over 2 TiB) with a GUID Partition Table (GPT).
CPU-independent architecture and drivers.
Flexible pre-OS environment with network capabilities.
CSM (Compatibility Support Module) to support booting legacy operating systems via a PC-BIOS-like emulation.
For more information, see http://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Interface. The following sections are not meant as a general UEFI overview; these are only hints about how some features are implemented in SUSE Linux Enterprise Desktop.
In the world of UEFI, securing the bootstrapping process means establishing a chain of trust. The “platform” is the root of this chain of trust; in the context of SUSE Linux Enterprise Desktop, the mainboard and the on-board firmware could be considered the “platform”. In other words, it is the hardware vendor, and the chain of trust flows from that hardware vendor to the component manufacturers, the OS vendors, etc.
The trust is expressed via public key cryptography. The hardware vendor puts a so-called Platform Key (PK) into the firmware, representing the root of trust. The trust relationship with operating system vendors and others is documented by signing their keys with the Platform Key.
Finally, security is established by requiring that no code will be executed by the firmware unless it has been signed by one of these “trusted” keys—be it an OS boot loader, some driver located in the flash memory of some PCI Express card or on disk, or be it an update of the firmware itself.
To use Secure Boot, you need to have your OS loader signed with a key trusted by the firmware, and you need the OS loader to verify that the kernel it loads can be trusted.
Key Exchange Keys (KEK) can be added to the UEFI key database. This way, you can use other certificates, as long as they are signed with the private part of the PK.
Microsoft’s Key Exchange Key (KEK) is installed by default.
The Secure Boot feature is enabled by default on UEFI/x86_64 installations. You can find the
option in the tab of the dialog. It supports booting when the secure boot is activated in the firmware, while making it possible to boot when it is deactivated.The Secure Boot feature requires that a GUID Partitioning Table (GPT) replaces the old partitioning with a Master Boot Record (MBR). If YaST detects EFI mode during the installation, it will try to create a GPT partition. UEFI expects to find the EFI programs on a FAT-formatted EFI System Partition (ESP).
Supporting UEFI Secure Boot requires having a boot loader with a digital signature that the firmware recognizes as a trusted key. That key is trusted by the firmware a priori, without requiring any manual intervention.
There are two ways of getting there. One is to work with hardware vendors to have them endorse a SUSE key, which SUSE then signs the boot loader with. The other way is to go through Microsoft’s Windows Logo Certification program to have the boot loader certified and have Microsoft recognize the SUSE signing key (that is, have it signed with their KEK). By now, SUSE got the loader signed by UEFI Signing Service (that is Microsoft in this case).
At the implementation layer, SUSE uses the shim
loader which is installed by default. It is a smart solution that avoids
legal issues, and simplifies the certification and signing step
considerably. The shim
loader’s job is to load a
boot loader such as GRUB 2 and verify it; this boot loader in
turn will load kernels signed by a SUSE key only. SUSE provides this
functionality since SLE11 SP3 on fresh installations with UEFI Secure Boot
enabled.
There are two types of trusted users:
First, those who hold the keys. The Platform Key (PK) allows almost everything. The Key Exchange Key (KEK) allows all a PK can except changing the PK.
Second, anyone with physical access to the machine. A user with physical access can reboot the machine, and configure UEFI.
UEFI offers two types of variables to fulfill the needs of those users:
The first is the so-called “Authenticated Variables”, which can be updated from both within the boot process (the so-called Boot Services Environment) and the running OS. This can be done only when the new value of the variable is signed with the same key that the old value of the variable was signed with. And they can only be appended to or changed to a value with a higher serial number.
The second is the so-called “Boot Services Only Variables”.
These variables are accessible to any code that runs during the boot
process. After the boot process ends and before the OS starts, the boot
loader must call the ExitBootServices
call. After
that, these variables are no longer accessible, and the OS cannot touch
them.
The various UEFI key lists are of the first type, as this allows online updating, adding, and blacklisting of keys, drivers, and firmware fingerprints. It is the second type of variable, the “Boot Services Only Variable”, that helps to implement Secure Boot in a secure and open source-friendly manner, and thus compatible with GPLv3.
SUSE starts with shim
—a small and simple EFI
boot loader signed by SUSE and Microsoft.
This allows shim
to load and execute.
shim
then goes on to verify that the boot loader
it wants to load is trusted.
In a default situation shim
will use an
independent SUSE certificate embedded in its body. In addition,
shim
will allow to “enroll”
additional keys, overriding the default SUSE key. In the following, we call
them “Machine Owner Keys” or MOKs for short.
Next the boot loader will verify and then boot the kernel, and the kernel will do the same on the modules.
If the user (“machine owner”) wants to replace any components
of the boot process, Machine Owner Keys (MOKs) are to be used. The
mokutils
tool will help with signing components
and managing MOKs.
The enrollment process begins with rebooting the machine and interrupting
the boot process (for example, pressing a key) when
shim
loads. shim
will
then go into enrollment mode, allowing the user to replace the default SUSE
key with keys from a file on the boot partition. If the user chooses to do
so, shim
will then calculate a hash of that file
and put the result in a “Boot Services Only” variable. This
allows shim
to detect any change of the file made
outside of Boot Services and thus avoid tampering with the list of
user-approved MOKs.
All of this happens during boot time—only verified code is executing now. Therefore, only a user present at the console can use the machine owner's set of keys. It cannot be malware or a hacker with remote access to the OS because hackers or malware can only change the file, but not the hash stored in the “Boot Services Only” variable.
The boot loader, after having been loaded and verified by
shim
, will call back to
shim
when it wants to verify the kernel—to
avoid duplication of the verification code. Shim
will use the same list of MOKs for this and tell the boot loader whether it
can load the kernel.
This way, you can install your own kernel or boot loader. It is only
necessary to install a new set of keys and authorize them by being
physically present during the first reboot. Because MOKs are a list rather
than a single MOK, you can make shim
trust keys
from several vendors, allowing dual- and multi-boot from the boot loader.
The following is based on https://en.opensuse.org/openSUSE:UEFI#Booting_a_custom_kernel.
Secure Boot does not prevent you from using a self-compiled kernel. You must sign it with your own certificate and make that certificate known to the firmware or MOK.
Create a custom X.509 key and certificate used for signing:
openssl req -new -x509 -newkey rsa:2048 -keyout key.asc \ -out cert.pem -nodes -days 666 -subj "/CN=$USER/"
For more information about creating certificates, see https://en.opensuse.org/openSUSE:UEFI_Image_File_Sign_Tools#Create_Your_Own_Certificate.
Package the key and the certificate as a PKCS#12 structure:
tux >
openssl pkcs12 -export -inkey key.asc -in cert.pem \
-name kernel_cert -out cert.p12
Generate an NSS database for use with pesign
:
tux >
certutil -d . -N
Import the key and the certificate contained in PKCS#12 into the NSS database:
tux >
pk12util -d . -i cert.p12
“Bless” the kernel with the new signature using
pesign
:
tux >
pesign -n . -c kernel_cert -i arch/x86/boot/bzImage \
-o vmlinuz.signed -s
List the signatures on the kernel image:
tux >
pesign -n . -S -i vmlinuz.signed
At that point, you can install the kernel in /boot
as usual. Because the kernel now has a custom signature the certificate
used for signing needs to be imported into the UEFI firmware or MOK.
Convert the certificate to the DER format for import into the firmware or MOK:
tux >
openssl x509 -in cert.pem -outform der -out cert.der
Copy the certificate to the ESP for easier access:
tux >
sudo
cp cert.der /boot/efi/
Use mokutil
to launch the MOK list automatically.
Import the certificate to MOK:
tux >
mokutil --root-pw --import cert.der
The --root-pw
option enables usage of the root
user directly.
Check the list of certificates that are prepared to be enrolled:
tux >
mokutil --list-new
Reboot the system; shim
should launch
MokManager. You need to enter the root
password to confirm the
import of the certificate to the MOK list.
Check if the newly imported key was enrolled:
tux >
mokutil --list-enrolled
Alternatively, this is the procedure if you want to launch MOK manually:
Reboot
In the GRUB 2 menu press the 'c
' key.
Type:
chainloader $efibootdir/MokManager.efi boot
Select
.
Navigate to the cert.der
file and press
Enter.
Follow the instructions to enroll the key. Normally this should be
pressing '0
' and then 'y
' to
confirm.
Alternatively, the firmware menu may provide ways to add a new key to the Signature Database.
There is no support for adding non-inbox drivers (that is, drivers that do not come with SUSE Linux Enterprise Desktop) during installation with Secure Boot enabled. The signing key used for SolidDriver/PLDP is not trusted by default.
It is possible to install third party drivers during installation with Secure Boot enabled in two different ways. In both cases:
Add the needed keys to the firmware database via firmware/system management tools before the installation. This option depends on the specific hardware you are using. Consult your hardware vendor for more information.
Use a bootable driver ISO from https://drivers.suse.com/ or your hardware vendor to enroll the needed keys in the MOK list at first boot.
To use the bootable driver ISO to enroll the driver keys to the MOK list, follow these steps:
Burn the ISO image above to an empty CD/DVD medium.
Start the installation using the new CD/DVD medium, having the standard installation media at hand or a URL to a network installation server.
If doing a network installation, enter the URL of the network
installation source on the boot command line using the
install=
option.
If doing installation from optical media, the installer will first boot from the driver kit and then ask to insert the first installation disk of the product.
An initrd containing updated drivers will be used for installation.
For more information, see https://drivers.suse.com/doc/Usage/Secure_Boot_Certificate.html.
When booting in Secure Boot mode, the following features apply:
Installation to UEFI default boot loader location, a mechanism to keep or restore the EFI boot entry.
Reboot via UEFI.
Xen hypervisor will boot with UEFI when there is no legacy BIOS to fall back to.
UEFI IPv6 PXE boot support.
UEFI videomode support, the kernel can retrieve video mode from UEFI to configure KMS mode with the same parameters.
UEFI booting from USB devices is supported.
When booting in Secure Boot mode, the following limitations apply:
To ensure that Secure Boot cannot be easily circumvented, some kernel features are disabled when running under Secure Boot.
Boot loader, kernel, and kernel modules must be signed.
Kexec and Kdump are disabled.
Hibernation (suspend on disk) is disabled.
Access to /dev/kmem
and
/dev/mem
is not possible, not even as root user.
Access to the I/O port is not possible, not even as root user. All X11 graphical drivers must use a kernel driver.
PCI BAR access through sysfs is not possible.
custom_method
in ACPI is not available.
debugfs for asus-wmi module is not available.
the acpi_rsdp
parameter does not have any effect on
the kernel.
https://www.uefi.org —UEFI home page where you can find the current UEFI specifications.
Blog posts by Olaf Kirch and Vojtěch Pavlík (the chapter above is heavily based on these posts):
https://en.opensuse.org/openSUSE:UEFI —UEFI with openSUSE.
This chapter describes how to configure GRUB 2, the boot loader used in SUSE® Linux Enterprise Desktop. It is the successor to the traditional GRUB boot loader—now called “GRUB Legacy”. GRUB 2 has been the default boot loader in SUSE® Linux Enterprise Desktop since version 12. A YaST module is available for configuring the most important settings. The boot procedure as a whole is outlined in Chapter 12, Introduction to the Boot Process. For details on Secure Boot support for UEFI machines, see Chapter 13, UEFI (Unified Extensible Firmware Interface).
The configuration is stored in different files.
More file systems are supported (for example, Btrfs).
Can directly read files stored on LVM or RAID devices.
The user interface can be translated and altered with themes.
Includes a mechanism for loading modules to support additional features, such as file systems, etc.
Automatically searches for and generates boot entries for other kernels and operating systems, such as Windows.
Includes a minimal Bash-like console.
The configuration of GRUB 2 is based on the following files:
/boot/grub2/grub.cfg
This file contains the configuration of the GRUB 2 menu items. It
replaces menu.lst
used in GRUB Legacy.
grub.cfg
should not be edited—it is automatically
generated by the command grub2-mkconfig -o /boot/grub2/grub.cfg
.
/boot/grub2/custom.cfg
This optional file is directly sourced by grub.cfg
at boot time and can be used to add custom items to the boot menu.
Starting with SUSE Linux Enterprise Desktop these entries will also
be parsed when using grub-once
.
/etc/default/grub
This file controls the user settings of GRUB 2 and usually includes additional environmental settings such as backgrounds and themes.
/etc/grub.d/
The scripts in this directory are read during execution of the command
grub2-mkconfig -o /boot/grub2/grub.cfg
. Their instructions are
integrated into the main configuration file
/boot/grub/grub.cfg
.
/etc/sysconfig/bootloader
This configuration file holds some basic settings like the boot loader type and whether to enable UEFI Secure Boot support.
/boot/grub2/x86_64-efi
,
/boot/grub2/power-ieee1275
These configuration files contain architecture-specific options.
GRUB 2 can be controlled in various ways. Boot entries from an existing
configuration can be selected from the graphical menu (splash screen). The
configuration is loaded from the file
/boot/grub2/grub.cfg
which is compiled from other
configuration files (see below). All GRUB 2 configuration files are
considered system files, and you need root
privileges to edit them.
After having manually edited GRUB 2 configuration files, you need to run
grub2-mkconfig -o /boot/grub2/grub.cfg
to activate the changes. However, this
is not necessary when changing the configuration with YaST, because YaST will
automatically run this command.
/boot/grub2/grub.cfg
#Edit source
The graphical splash screen with the boot menu is based on the GRUB 2
configuration file /boot/grub2/grub.cfg
, which
contains information about all partitions or operating systems that can be
booted by the menu.
Every time the system is booted, GRUB 2 loads the menu file directly from
the file system. For this reason, GRUB 2 does not need to be re-installed
after changes to the configuration file. grub.cfg
is
automatically rebuilt with kernel installations or removals.
grub.cfg
is compiled from the file
/etc/default/grub
and scripts found in the
/etc/grub.d/
directory when running the command
grub2-mkconfig -o /boot/grub2/grub.cfg
. Therefore you should never
edit the file manually. Instead, edit the related source files or use the
YaST module to modify the configuration as
described in Section 14.3, “Configuring the Boot Loader with YaST”.
/etc/default/grub
#Edit sourceMore general options of GRUB 2 belong here, such as the time the menu is displayed, or the default OS to boot. To list all available options, see the output of the following command:
tux >
grep "export GRUB_DEFAULT" -A50 /usr/sbin/grub2-mkconfig | grep GRUB_
In addition to already defined variables, the user may introduce their own
variables, and use them later in the scripts found in the
/etc/grub.d
directory.
After having edited /etc/default/grub
, update the main
configuration file with grub2-mkconfig -o /boot/grub2/grub.cfg
.
All options set in this file are general options that affect all boot entries. Specific options for Xen kernels or the Xen hypervisor can be set via the GRUB_*_XEN_* configuration options. See below for details.
GRUB_DEFAULT
Sets the boot menu entry that is booted by default. Its value can be a numeric value, the complete name of a menu entry, or “saved”.
GRUB_DEFAULT=2
boots the third (counted from zero)
boot menu entry.
GRUB_DEFAULT="2>0"
boots the first submenu entry
of the third top-level menu entry.
GRUB_DEFAULT="Example boot menu entry"
boots the menu
entry with the title “Example boot menu entry”.
GRUB_DEFAULT=saved
boots the entry specified by the
grub2-once
or grub2-set-default
commands. While grub2-reboot
sets the
default boot entry for the next reboot only,
grub2-set-default
sets the default boot entry until
changed. grub2-editenv list
lists the next boot entry.
GRUB_HIDDEN_TIMEOUT
Waits the specified number of seconds for the user to press a key.
During the period no menu is shown unless the user presses a key. If no
key is pressed during the time specified, the control is passed to
GRUB_TIMEOUT
.
GRUB_HIDDEN_TIMEOUT=0
first checks whether
Shift is pressed and shows the boot menu if yes,
otherwise immediately boots the default menu entry. This is the default
when only one bootable OS is identified by GRUB 2.
GRUB_HIDDEN_TIMEOUT_QUIET
If false
is specified, a countdown timer is displayed
on a blank screen when the GRUB_HIDDEN_TIMEOUT
feature is active.
GRUB_TIMEOUT
Time period in seconds the boot menu is displayed before automatically
booting the default boot entry. If you press a key, the timeout is
cancelled and GRUB 2 waits for you to make the selection manually.
GRUB_TIMEOUT=-1
will cause the menu to be displayed
until you select the boot entry manually.
GRUB_CMDLINE_LINUX
Entries on this line are added at the end of the boot entries for normal and recovery mode. Use it to add kernel parameters to the boot entry.
GRUB_CMDLINE_LINUX_DEFAULT
Same as GRUB_CMDLINE_LINUX
but the entries are
appended in the normal mode only.
GRUB_CMDLINE_LINUX_RECOVERY
Same as GRUB_CMDLINE_LINUX
but the entries are
appended in the recovery mode only.
GRUB_CMDLINE_LINUX_XEN_REPLACE
This entry will completely replace the
GRUB_CMDLINE_LINUX
parameters for all Xen boot
entries.
GRUB_CMDLINE_LINUX_XEN_REPLACE_DEFAULT
Same as GRUB_CMDLINE_LINUX_XEN_REPLACE
but it will
only replace parameters ofGRUB_CMDLINE_LINUX_DEFAULT
.
GRUB_CMDLINE_XEN
This entry specifies the kernel parameters for the Xen guest kernel
only—the operation principle is the same as for
GRUB_CMDLINE_LINUX
.
GRUB_CMDLINE_XEN_DEFAULT
Same as GRUB_CMDLINE_XEN
—the operation
principle is the same as for
GRUB_CMDLINE_LINUX_DEFAULT
.
GRUB_TERMINAL
Enables and specifies an input/output terminal device. Can be
console
(PC BIOS and EFI consoles),
serial
(serial terminal),
ofconsole
(Open Firmware console), or the default
gfxterm
(graphics-mode output). It is also possible
to enable more than one device by quoting the required options, for
example GRUB_TERMINAL="console serial"
.
GRUB_GFXMODE
The resolution used for the gfxterm
graphical
terminal. Note that you can only use modes supported by your graphics
card (VBE). The default is ‘auto’, which tries to select a preferred
resolution. You can display the screen resolutions available to GRUB 2
by typing videoinfo
in the GRUB 2 command line. The
command line is accessed by typing C when the GRUB 2
boot menu screen is displayed.
You can also specify a color depth by appending it to the resolution
setting, for example GRUB_GFXMODE=1280x1024x24
.
GRUB_BACKGROUND
Set a background image for the gfxterm
graphical
terminal. The image must be a file readable by GRUB 2 at boot time, and
it must end with the .png
, .tga
,
.jpg
, or .jpeg
suffix. If
necessary, the image will be scaled to fit the screen.
GRUB_DISABLE_OS_PROBER
If this option is set to true
, automatic searching
for other operating systems is disabled. Only the kernel images in
/boot/
and the options from your own scripts in
/etc/grub.d/
are detected.
SUSE_BTRFS_SNAPSHOT_BOOTING
If this option is set to true
, GRUB 2 can boot
directly into Snapper snapshots. For more information, see
Section 7.3, “System Rollback by Booting from Snapshots”.
For a complete list of options, see the GNU GRUB manual.
/etc/grub.d
#Edit source
The scripts in this directory are read during execution of the
command grub2-mkconfig -o /boot/grub2/grub.cfg
. Their instructions are
incorporated into /boot/grub2/grub.cfg
. The order of
menu items in grub.cfg
is determined by the order in
which the files in this directory are run. Files with a leading numeral are
executed first, beginning with the lowest number.
00_header
is run before 10_linux
,
which would run before 40_custom
. If files with
alphabetic names are present, they are executed after the numerically-named
files. Only executable files generate output to
grub.cfg
during execution of
grub2-mkconfig
. By default all files in the
/etc/grub.d
directory are executable.
grub.cfg
Because /boot/grub2/grub.cfg
is recompiled each time
grub2-mkconfig
is run, any custom content is lost.
If you want to insert your lines directly into
/boot/grub2/grub.cfg
without losing them after
grub2-mkconfig
is run, insert them between
### BEGIN /etc/grub.d/90_persistent ###
and
### END /etc/grub.d/90_persistent ###
The 90_persistent
script ensures that such
content will be preserved.
A list of the most important scripts follows:
00_header
Sets environmental variables such as system file locations, display
settings, themes, and previously saved entries. It also imports
preferences stored in the /etc/default/grub
.
Normally you do not need to make changes to this file.
10_linux
Identifies Linux kernels on the root device and creates relevant menu entries. This includes the associated recovery mode option if enabled. Only the latest kernel is displayed on the main menu page, with additional kernels included in a submenu.
30_os-prober
This script uses os-prober
to search for Linux and
other operating systems and places the results in the GRUB 2 menu. There
are sections to identify specific other operating systems, such as
Windows or macOS.
40_custom
This file provides a simple way to include custom boot entries into
grub.cfg
. Make sure that you do not change the
exec tail -n +3 $0
part at the beginning.
The processing sequence is set by the preceding numbers with the lowest number being executed first. If scripts are preceded by the same number the alphabetical order of the complete name decides the order.
/boot/grub2/custom.cfg
If you create /boot/grub2/custom.cfg
and fill
it with content, it will be automatically included into
/boot/grub2/grub.cfg
just after 40_custom at
boot time.
In GRUB Legacy, the device.map
configuration file was
used to derive Linux device names from BIOS drive numbers. The mapping
between BIOS drives and Linux devices cannot always be guessed correctly.
For example, GRUB Legacy would get a wrong order if the boot sequence of
IDE and SCSI drives is exchanged in the BIOS configuration.
GRUB 2 avoids this problem by using device ID strings (UUIDs) or file
system labels when generating grub.cfg
. GRUB 2
utilities create a temporary device map on the fly, which is usually
sufficient, particularly in the case of single-disk systems.
However, if you need to override the GRUB 2's automatic device mapping
mechanism, create your custom mapping file
/boot/grub2/device.map
. The following example changes
the mapping to make DISK 3
the boot disk. Note that
GRUB 2 partition numbers start with 1
and not with
0
as in GRUB Legacy.
(hd1) /dev/disk-by-id/DISK3 ID (hd2) /dev/disk-by-id/DISK1 ID (hd3) /dev/disk-by-id/DISK2 ID
Even before the operating system is booted, GRUB 2 enables access to file systems. Users without root permissions can access files in your Linux system to which they have no access after the system is booted. To block this kind of access or to prevent users from booting certain menu entries, set a boot password.
If set, the boot password is required on every boot, which means the system does not boot automatically.
Proceed as follows to set a boot password. Alternatively use YaST ().
Encrypt the password using grub2-mkpasswd-pbkdf2:
tux >
sudo
grub2-mkpasswd-pbkdf2 Password: **** Reenter password: **** PBKDF2 hash of your password is grub.pbkdf2.sha512.10000.9CA4611006FE96BC77A...
Paste the resulting string into the file
/etc/grub.d/40_custom
together with the set
superusers
command.
set superusers="root" password_pbkdf2 root grub.pbkdf2.sha512.10000.9CA4611006FE96BC77A...
To import the changes into the main configuration file, run:
tux >
sudo
grub2-mkconfig -o /boot/grub2/grub.cfg
After you reboot, you will be prompted for a user name and a password when
trying to boot a menu entry. Enter root
and the password
you typed during the grub2-mkpasswd-pbkdf2
command. If
the credentials are correct, the system will boot the selected boot entry.
For more information, see https://www.gnu.org/software/grub/manual/grub.html#Security.
The easiest way to configure general options of the boot loader in your SUSE Linux Enterprise Desktop system is to use the YaST module. In the , select › . The module shows the current boot loader configuration of your system and allows you to make changes.
Use the
tab to view and change settings related to type, location and advanced loader settings. You can choose whether to use GRUB 2 in standard or EFI mode.If you have an EFI system you can only install GRUB2-EFI, otherwise your system is no longer bootable.
To reinstall the boot loader, make sure to change a setting in YaST and then change it back. For example, to reinstall GRUB2-EFI, select
first and then immediately switch back to .Otherwise, the boot loader may only be partially reinstalled.
To use a boot loader other than the ones listed, select
. Read the documentation of your boot loader carefully before choosing this option.
The default location of the boot loader depends on the partition setup and
is either the Master Boot Record (MBR) or the boot sector of the
/
partition. To modify the location of the boot loader,
follow these steps:
Select the
tab and then choose one of the following options for :
This installs the boot loader in the MBR of the disk containing the
directory /boot
. Usually this will be the disk
mounted to /
, but if /boot
is
mounted to a separate partition on a different disk, the MBR of that
disk will be used.
This installs the boot loader in the boot sector of the
/
partition.
Use this option to specify the location of the boot loader manually.
Click
to apply your changes.The
tab includes the following additional options:
Activates the partition that contains the
/boot
directory. For POWER systems it
activates the PReP partition. Use this option on systems with
old BIOS and/or legacy operating systems because they may fail
to boot from a non-active partition. It is safe to leave this
option active.
If MBR contains a custom 'non-GRUB' code, this option replaces it with a generic, operating system independent code. If you deactivate this option, the system may become unbootable.
Starts TrustedGRUB2, which supports trusted computing functionality (Trusted Platform Module (TPM)). For more information refer to https://github.com/Sirrix-AG/TrustedGRUB2.
The
section includes the following options:This is appropriate for traditional legacy BIOS booting.
This is appropriate for UEFI booting.
This is usually the best choice if you have an already working system.
In most cases YaST defaults to the appropriate choice.
If your computer has more than one hard disk, you can specify the boot sequence of the disks. The first disk in the list is where GRUB 2 will be installed in the case of booting from MBR. It is the disk where SUSE Linux Enterprise Desktop is installed by default. The rest of the list is a hint for GRUB 2's device mapper (see Section 14.2.4, “Mapping between BIOS Drives and Linux Devices”).
The default value is usually valid for almost all deployments. If you change the boot order of disks wrongly, the system may become unbootable on the next reboot. For example, if the first disk in the list is not part of the BIOS boot order, and the other disks in the list have empty MBRs.
Open the
tab.Click
.If more than one disk is listed, select a disk and click
or to reorder the displayed disks.Click
two times to save the changes.Advanced boot parameters can be configured via the
tab.Change the value of
by typing in a new value and clicking the appropriate arrow key with your mouse.When selected, the boot loader searches for other systems like Windows or other Linux installations.
Hides the boot menu and boots the default entry.
Select the desired entry from the “Default Boot Section” list. Note that the “>” sign in the boot entry name delimits the boot section and its subsection.
Protects the boot loader and the system with an additional password. For
details on manual configuration, see Section 14.2.6, “Setting a Boot Password”.
If this option is activated, the boot password is required on every boot,
which means the system does not boot automatically. However, if you prefer
the behavior of GRUB 1, additionally enable . With this setting, anybody is allowed to select
a boot entry and boot the system, whereas the password for the GRUB 2 root
user is only required for modifying boot entries.
Specify optional kernel parameters here to enable/disable system features, add drivers, etc.
SUSE has released one or more kernel boot command line parameters for all software mitigations that have been deployed to prevent CPU side-channel attacks. Some of those may result in performance loss. Choose one the following options to strike a balance between security and performance, depending on your setting:
Enables all mitigations required for your CPU model, but does not protect against cross-CPU thread attacks. This setting may impact performance to some degree, depending on the workload. .
Provides the full set of available security mitigations. Enables all mitigations required for your CPU model. In addition, it disables Simultaneous Multithreading (SMT) to avoid side-channel attacks across multiple CPU threads. This setting may further impact performance, depending on the workload. .
Disables all mitigations. Side-channel attacks against your CPU are possible, depending on the CPU model. This setting has no impact on performance. .
Does not set any mitigation level. Specify your CPU mitigations manually by using the kernel command line options. .
When checked, the boot menu appears on a graphical splash screen rather than in a text mode. The resolution of the boot screen is set automatically by default, but you can manually set it via
. The graphical theme definition file can be specified with the file-chooser. Only change this if you want to apply your own, custom-made theme.
If your machine is controlled via a serial console, activate this option
and specify which COM port to use at which speed. See info
grub
or
http://www.gnu.org/software/grub/manual/grub.html#Serial-terminal
grub2-mkconfig
Generates a new /boot/grub2/grub.cfg
based on
/etc/default/grub
and the scripts from
/etc/grub.d/
.
grub2-mkconfig -o /boot/grub2/grub.cfg
Running grub2-mkconfig
without any parameters prints
the configuration to STDOUT where it can be reviewed. Use
grub2-script-check
after
/boot/grub2/grub.cfg
has been written to check its
syntax.
grub2-mkconfig
Cannot Repair UEFI Secure Boot TablesIf you are using UEFI Secure Boot and your system is not reaching GRUB 2 correctly anymore, you may need to additionally reinstall Shim and regenerate the UEFI boot table. To do so, use:
root #
shim-install --config-file=/boot/grub2/grub.cfg
grub2-mkrescue
Creates a bootable rescue image of your installed GRUB 2 configuration.
grub2-mkrescue -o save_path/name.iso iso
grub2-script-check
Checks the given file for syntax errors.
grub2-script-check /boot/grub2/grub.cfg
grub2-once
Set the default boot entry for the next boot only. To get the list of
available boot entries use the --list
option.
grub2-once number_of_the_boot_entry
grub2-once
HelpCall the program without any option to get a full list of all possible options.
Extensive information about GRUB 2 is available at https://www.gnu.org/software/grub/. Also refer to the
grub
info page. You can also
search for the keyword “GRUB 2” in the Technical Information
Search at https://www.suse.com/support to get
information about special issues.
systemd
Daemon #Edit source
The program systemd
is the process with process ID 1. It is responsible for
initializing the system in the required way. systemd
is started directly by
the kernel and resists signal 9, which normally terminates processes.
All other programs are either started directly by systemd or by one of its
child processes.
Systemd is a replacement for the System V init daemon. systemd
is fully
compatible with System V init (by supporting init scripts). One of the main
advantages of systemd is that it considerably speeds up boot time by
aggressively paralleling service starts. Furthermore, systemd only starts a
service when it is really needed. Daemons are not started unconditionally at
boot time, but rather when being required for the first time. systemd also
supports Kernel Control Groups (cgroups), snapshotting and restoring the
system state and more. See http://www.freedesktop.org/wiki/Software/systemd/ for details.
This section will go into detail about the concept behind systemd.
systemd is a system and session manager for Linux, compatible with System V and LSB init scripts. The main features are:
provides aggressive parallelization capabilities
uses socket and D-Bus activation for starting services
offers on-demand starting of daemons
keeps track of processes using Linux cgroups
supports snapshotting and restoring of the system state
maintains mount and automount points
implements an elaborate transactional dependency-based service control logic
A unit configuration file contains information about a service, a socket, a device, a mount point, an automount point, a swap file or partition, a start-up target, a watched file system path, a timer controlled and supervised by systemd, a temporary system state snapshot, a resource management slice or a group of externally created processes. “Unit file” is a generic term used by systemd for the following:
Service. Information about a process (for example running a daemon); file ends with .service
Targets. Used for grouping units and as synchronization points during start-up; file ends with .target
Sockets.
Information about an IPC or network socket or a file system FIFO, for
socket-based activation (like
inetd
); file ends with .socket
Path. Used to trigger other units (for example running a service when files change); file ends with .path
Timer. Information about a timer controlled, for timer-based activation; file ends with .timer
Mount point. Usually auto-generated by the fstab generator; file ends with .mount
Automount point. Information about a file system automount point; file ends with .automount
Swap. Information about a swap device or file for memory paging; file ends with .swap
Device. Information about a device unit as exposed in the sysfs/udev(7) device tree; file ends with .device
Scope / Slice. A concept for hierarchically managing resources of a group of processes; file ends with .scope/.slice
For more information about systemd.unit see http://www.freedesktop.org/software/systemd/man/systemd.unit.html
The System V init system uses several commands to handle services—the
init scripts, insserv
, telinit
and
others. systemd makes it easier to manage services, since there is only one
command to memorize for the majority of service-handling tasks:
systemctl
. It uses the “command plus
subcommand” notation like git
or
zypper
:
systemctl GENERAL OPTIONS SUBCOMMAND SUBCOMMAND OPTIONS
See man 1 systemctl
for a complete manual.
If the output goes to a terminal (and not to a pipe or a file, for example)
systemd commands send long output to a pager by default. Use the
--no-pager
option to turn off paging mode.
systemd also supports bash-completion, allowing you to enter the first
letters of a subcommand and then press →| to
automatically complete it. This feature is only available in the
bash
shell and requires the installation of the
package bash-completion
.
Subcommands for managing services are the same as for managing a service
with System V init (start
, stop
,
...). The general syntax for service management commands is as follows:
systemctl reload|restart|start|status|stop|... MY_SERVICE(S)
rcMY_SERVICE(S) reload|restart|start|status|stop|...
systemd allows you to manage several services in one go. Instead of executing init scripts one after the other as with System V init, execute a command like the following:
tux >
sudo
systemctl start MY_1ST_SERVICE MY_2ND_SERVICE
To list all services available on the system:
tux >
sudo
systemctl list-unit-files --type=service
The following table lists the most important service management commands for systemd and System V init:
Task |
systemd Command |
System V init Command |
---|---|---|
Starting. |
start |
start |
Stopping. |
stop |
stop |
Restarting. Shuts down services and starts them afterward. If a service is not yet running it will be started. |
restart |
restart |
Restarting conditionally. Restarts services if they are currently running. Does nothing for services that are not running. |
try-restart |
try-restart |
Reloading.
Tells services to reload their configuration files without
interrupting operation. Use case: Tell Apache to reload a modified
|
reload |
reload |
Reloading or restarting. Reloads services if reloading is supported, otherwise restarts them. If a service is not yet running it will be started. |
reload-or-restart |
n/a |
Reloading or restarting conditionally. Reloads services if reloading is supported, otherwise restarts them if currently running. Does nothing for services that are not running. |
reload-or-try-restart |
n/a |
Getting detailed status information.
Lists information about the status of services. The |
status |
status |
Getting short status information. Shows whether services are active or not. |
is-active |
status |
The service management commands mentioned in the previous section let you manipulate services for the current session. systemd also lets you permanently enable or disable services, so they are automatically started when requested or are always unavailable. You can either do this by using YaST, or on the command line.
The following table lists enabling and disabling commands for systemd and System V init:
When enabling a service on the command line, it is not started
automatically. It is scheduled to be started with the next system
start-up or runlevel/target change. To immediately start a service after
having enabled it, explicitly run systemctl start
MY_SERVICE
or rc
MY_SERVICE start
.
Task |
|
System V init Command |
---|---|---|
Enabling. |
|
|
Disabling. |
|
|
Checking. Shows whether a service is enabled or not. |
|
|
Re-enabling. Similar to restarting a service, this command first disables and then enables a service. Useful to re-enable a service with its defaults. |
|
n/a |
Masking. After “disabling” a service, it can still be started manually. To completely disable a service, you need to mask it. Use with care. |
|
n/a |
Unmasking. A service that has been masked can only be used again after it has been unmasked. |
|
n/a |
The entire process of starting the system and shutting it down is maintained by systemd. From this point of view, the kernel can be considered a background process to maintain all other processes and adjust CPU time and hardware access according to requests from other programs.
With System V init the system was booted into a so-called
“Runlevel”. A runlevel defines how the system is started and
what services are available in the running system. Runlevels are numbered;
the most commonly known ones are 0
(shutting down the
system), 3
(multiuser with network) and
5
(multiuser with network and display manager).
systemd introduces a new concept by using so-called “target
units”. However, it remains fully compatible with the runlevel
concept. Target units are named rather than numbered and serve specific
purposes. For example, the targets local-fs.target
and swap.target
mount local file systems and swap
spaces.
The target graphical.target
provides a multiuser
system with network and display manager capabilities and is equivalent to
runlevel 5. Complex targets, such as
graphical.target
act as “meta”
targets by combining a subset of other targets. Since systemd makes it easy
to create custom targets by combining existing targets, it offers great
flexibility.
The following list shows the most important systemd target units. For a
full list refer to man 7 systemd.special
.
default.target
The target that is booted by default. Not a “real” target,
but rather a symbolic link to another target like
graphic.target
. Can be permanently changed via
YaST (see Section 15.4, “Managing Services with YaST”). To change it for
a session, use the kernel parameter
systemd.unit=MY_TARGET.target
at the boot prompt.
emergency.target
Starts an emergency shell on the console. Only use it at the boot prompt
as systemd.unit=emergency.target
.
graphical.target
Starts a system with network, multiuser support and a display manager.
halt.target
Shuts down the system.
mail-transfer-agent.target
Starts all services necessary for sending and receiving mails.
multi-user.target
Starts a multiuser system with network.
reboot.target
Reboots the system.
rescue.target
Starts a single-user system without network.
To remain compatible with the System V init runlevel system, systemd
provides special targets named
runlevelX.target
mapping the
corresponding runlevels numbered X.
If you want to know the current target, use the command: systemctl
get-default
systemd
Target Units #
System V runlevel |
|
Purpose |
---|---|---|
0 |
|
System shutdown |
1, S |
|
Single-user mode |
2 |
|
Local multiuser without remote network |
3 |
|
Full multiuser with network |
4 |
|
Unused/User-defined |
5 |
|
Full multiuser with network and display manager |
6 |
|
System reboot |
/etc/inittab
The runlevels in a System V init system are configured in
/etc/inittab
. systemd does not
use this configuration. Refer to
Section 15.5.3, “Creating Custom Targets” for instructions on how
to create your own bootable target.
Use the following commands to operate with target units:
Task |
systemd Command |
System V init Command |
---|---|---|
Change the current target/runlevel |
|
|
Change to the default target/runlevel |
|
n/a |
Get the current target/runlevel |
With systemd there is usually more than one active target. The command lists all currently active targets. |
or
|
persistently change the default runlevel |
Use the Services Manager or run the following command:
|
Use the Services Manager or change the line
in |
Change the default runlevel for the current boot process |
Enter the following option at the boot prompt
|
Enter the desired runlevel number at the boot prompt. |
Show a target's/runlevel's dependencies |
“Requires” lists the hard dependencies (the ones that must be resolved), whereas “Wants” lists the soft dependencies (the ones that get resolved if possible). |
n/a |
systemd offers the means to analyze the system start-up process. You can
review the list of all services and their status (rather than having to
parse /var/log/
). systemd also allows you to scan the
start-up procedure to find out how much time each service start-up
consumes.
To review the complete list of services that have been started since
booting the system, enter the command systemctl
. It
lists all active services like shown below (shortened). To get more
information on a specific service, use systemctl status
MY_SERVICE
.
root #
systemctl
UNIT LOAD ACTIVE SUB JOB DESCRIPTION
[...]
iscsi.service loaded active exited Login and scanning of iSC+
kmod-static-nodes.service loaded active exited Create list of required s+
libvirtd.service loaded active running Virtualization daemon
nscd.service loaded active running Name Service Cache Daemon
chronyd.service loaded active running NTP Server Daemon
polkit.service loaded active running Authorization Manager
postfix.service loaded active running Postfix Mail Transport Ag+
rc-local.service loaded active exited /etc/init.d/boot.local Co+
rsyslog.service loaded active running System Logging Service
[...]
LOAD = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB = The low-level unit activation state, values depend on unit type.
161 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.
To restrict the output to services that failed to start, use the
--failed
option:
root #
systemctl --failed
UNIT LOAD ACTIVE SUB JOB DESCRIPTION
apache2.service loaded failed failed apache
NetworkManager.service loaded failed failed Network Manager
plymouth-start.service loaded failed failed Show Plymouth Boot Screen
[...]
To debug system start-up time, systemd offers the
systemd-analyze
command. It shows the total start-up
time, a list of services ordered by start-up time and can also generate an
SVG graphic showing the time services took to start in relation to the
other services.
root #
systemd-analyze
Startup finished in 2666ms (kernel) + 21961ms (userspace) = 24628ms
root #
systemd-analyze blame
15.000s backup-rpmdb.service
14.879s mandb.service
7.646s backup-sysconfig.service
4.940s postfix.service
4.921s logrotate.service
4.640s libvirtd.service
4.519s display-manager.service
3.921s btrfsmaintenance-refresh.service
3.466s lvm2-monitor.service
2.774s plymouth-quit-wait.service
2.591s firewalld.service
2.137s initrd-switch-root.service
1.954s ModemManager.service
1.528s rsyslog.service
1.378s apparmor.service
[...]
root #
systemd-analyze plot > jupiter.example.com-startup.svg
The above-mentioned commands let you review the services that started and
the time it took to start them. If you need to know more details, you can
tell systemd
to verbosely log the complete start-up procedure by
entering the following parameters at the boot prompt:
systemd.log_level=debug systemd.log_target=kmsg
Now systemd
writes its log messages into the kernel ring buffer. View
that buffer with dmesg
:
tux >
dmesg -T | less
systemd is compatible with System V, allowing you to still use existing
System V init scripts. However, there is at least one known issue where a
System V init script does not work with systemd out of the box: starting a
service as a different user via su
or
sudo
in init scripts will result in a failure of the
script, producing an “Access denied” error.
When changing the user with su
or
sudo
, a PAM session is started. This session will be
terminated after the init script is finished. As a consequence, the service
that has been started by the init script will also be terminated. To work
around this error, proceed as follows:
Create a service file wrapper with the same name as the init script plus
the file name extension .service
:
[Unit] Description=DESCRIPTION After=network.target [Service] User=USER Type=forking1 PIDFile=PATH TO PID FILE1 ExecStart=PATH TO INIT SCRIPT start ExecStop=PATH TO INIT SCRIPT stop ExecStopPost=/usr/bin/rm -f PATH TO PID FILE1 [Install] WantedBy=multi-user.target2
Replace all values written in UPPERCASE LETTERS with appropriate values.
Start the daemon with systemctl start
APPLICATION
.
Basic service management can also be done with the YaST Services Manager module. It supports starting, stopping, enabling and disabling services. It also lets you show a service's status and change the default target. Start the YaST module with
› › .To change the target the system boots into, choose a target from the
drop-down box. The most often used targets are (starting a graphical login screen) and (starting the system in command line mode).Select a service from the table. The
column shows whether it is currently running ( ) or not ( ). Toggle its status by choosing or .Starting or stopping a service changes its status for the currently running session. To change its status throughout a reboot, you need to enable or disable it.
Services can either be started automatically at boot time or manually. Select a service from the table. The
column shows whether it is currently started or . Toggle its status by choosing .To change a service status in the current session, you need to start or stop it as described above.
To view the status message of a service, select it from the list and
choose systemctl
-l
status
MY_SERVICE.
systemd
#Edit source
The following sections contain some examples for
systemd
customization.
Always do systemd customization in /etc/systemd/
,
never in /usr/lib/systemd/
.
Otherwise your changes will be overwritten by the next update of systemd.
The systemd unit files are located in
/usr/lib/systemd/system
. If you want to customize
them, proceed as follows:
Copy the files you want to modify from
/usr/lib/systemd/system
to
/etc/systemd/system
. Keep the file names identical
to the original ones.
Modify the copies in /etc/systemd/system
according
to your needs.
For an overview of your configuration changes, use the
systemd-delta
command. It can compare and identify
configuration files that override other configuration files. For details,
refer to the systemd-delta
man page.
The modified files in /etc/systemd
will take
precedence over the original files in
/usr/lib/systemd/system
, provided that their file name
is the same.
xinetd
Services to systemd
#Edit source
Since the release of SUSE Linux Enterprise Desktop 15, the xinetd
infrastructure has been removed. This section outlines how to convert
existing custom xinetd
service files to systemd
sockets.
For each xinetd
service file, you need at least
two systemd
unit files: the socket file (*.socket
)
and an associated service file (*.service
). The
socket file tells systemd
which socket to create, and the service file
tells systemd
which executable to start.
Consider the following example xinetd
service
file:
root #
cat /etc/xinetd.d/example
service example
{
socket_type = stream
protocol = tcp
port = 10085
wait = no
user = user
group = users
groups = yes
server = /usr/libexec/example/exampled
server_args = -auth=bsdtcp exampledump
disable = no
}
To convert it to systemd
, you need the following two matching files:
root #
cat /usr/lib/systemd/system/example.socket
[Socket]
ListenStream=0.0.0.0:10085
Accept=false
[Install]
WantedBy=sockets.target
root #
cat /usr/lib/systemd/system/example.service
[Unit]
Description=example
[Service]
ExecStart=/usr/libexec/example/exampled -auth=bsdtcp exampledump
User=user
Group=users
StandardInput=socket
For a complete list of the systemd
'socket' and 'service' file options,
refer to the systemd.socket and systemd.service manual pages (man
5 systemd.socket
, man 5 systemd.service
).
If you only want to add a few lines to a configuration file or modify a small part of it, you can use so-called “drop-in” files. Drop-in files let you extend the configuration of unit files without having to edit or override the unit files themselves.
For example, to change one value for the FOOBAR
service located in
/usr/lib/systemd/system/FOOBAR.SERVICE
,
proceed as follows:
Create a directory called
/etc/systemd/system/FOOBAR.service.d/
.
Note the .d
suffix. The directory must otherwise be
named like the service that you want to patch with the drop-in file.
In that directory, create a file
WHATEVERMODIFICATION.conf
.
Make sure it only contains the line with the value that you want to modify.
Save your changes to the file. It will be used as an extension of the original file.
On System V init SUSE systems, runlevel 4 is unused to allow
administrators to create their own runlevel configuration. systemd allows
you to create any number of custom targets. It is suggested to start by
adapting an existing target such as
graphical.target
.
Copy the configuration file
/usr/lib/systemd/system/graphical.target
to
/etc/systemd/system/MY_TARGET.target
and adjust it according to your needs.
The configuration file copied in the previous step already covers the
required (“hard”) dependencies for the target. To also cover
the wanted (“soft”) dependencies, create a directory
/etc/systemd/system/MY_TARGET.target.wants
.
For each wanted service, create a symbolic link from
/usr/lib/systemd/system
into
/etc/systemd/system/MY_TARGET.target.wants
.
When you have finished setting up the target, reload the systemd configuration to make the new target available:
tux >
sudo
systemctl daemon-reload
The following sections cover advanced topics for system administrators. For even more advanced systemd documentation, refer to Lennart Pöttering's series about systemd for administrators at http://0pointer.de/blog/projects.
systemd
supports cleaning temporary directories regularly. The
configuration from the previous system version is automatically migrated
and active. tmpfiles.d
—which is responsible for
managing temporary files—reads its configuration from
/etc/tmpfiles.d/*.conf
,
/run/tmpfiles.d/*.conf
, and
/usr/lib/tmpfiles.d/*.conf
files. Configuration placed
in /etc/tmpfiles.d/*.conf
overrides related
configurations from the other two directories
(/usr/lib/tmpfiles.d/*.conf
is where packages store
their configuration files).
The configuration format is one line per path containing action and path, and optionally mode, ownership, age and argument fields, depending on the action. The following example unlinks the X11 lock files:
Type Path Mode UID GID Age Argument r /tmp/.X[0-9]*-lock
To get the status the tmpfile timer:
tux >
sudo
systemctl status systemd-tmpfiles-clean.timer systemd-tmpfiles-clean.timer - Daily Cleanup of Temporary Directories Loaded: loaded (/usr/lib/systemd/system/systemd-tmpfiles-clean.timer; static) Active: active (waiting) since Tue 2018-04-09 15:30:36 CEST; 1 weeks 6 days ago Docs: man:tmpfiles.d(5) man:systemd-tmpfiles(8) Apr 09 15:30:36 jupiter systemd[1]: Starting Daily Cleanup of Temporary Directories. Apr 09 15:30:36 jupiter systemd[1]: Started Daily Cleanup of Temporary Directories.
For more information on temporary files handling, see man 5
tmpfiles.d
.
Section 15.6.9, “Debugging Services” explains how
to view log messages for a given service. However, displaying log messages
is not restricted to service logs. You can also access and query the
complete log messages written by systemd
—the so-called
“Journal”. Use the command
journalctl
to display the complete log messages
starting with the oldest entries. Refer to man 1
journalctl
for options such as applying filters or
changing the output format.
You can save the current state of systemd
to a named snapshot and later
revert to it with the isolate
subcommand. This is useful
when testing services or custom targets, because it allows you to return to
a defined state at any time. A snapshot is only available in the current
session and will automatically be deleted on reboot. A snapshot name must
end in .snapshot
.
tux >
sudo
systemctl snapshot MY_SNAPSHOT.snapshot
tux >
sudo
systemctl delete MY_SNAPSHOT.snapshot
tux >
sudo
systemctl show MY_SNAPSHOT.snapshot
tux >
sudo
systemctl isolate MY_SNAPSHOT.snapshot
With systemd
, kernel modules can automatically be loaded at boot time via
a configuration file in /etc/modules-load.d
. The file
should be named MODULE.conf and have the
following content:
# load module MODULE at boot time MODULE
In case a package installs a configuration file for loading a kernel
module, the file gets installed to
/usr/lib/modules-load.d
. If two configuration files
with the same name exist, the one in
/etc/modules-load.d
tales precedence.
For more information, see the modules-load.d(5)
man page.
With System V init actions that need to be performed before loading a
service, needed to be specified in /etc/init.d/before.local
. This procedure is no longer supported with systemd. If you
need to do actions before starting services, do the following:
Create a drop-in file in /etc/modules-load.d
directory (see man modules-load.d
for the syntax)
Create a drop-in file in /etc/tmpfiles.d
(see
man tmpfiles.d
for the syntax)
Create a system service file, for example
/etc/systemd/system/before.service
, from the
following template:
[Unit] Before=NAME OF THE SERVICE YOU WANT THIS SERVICE TO BE STARTED BEFORE [Service] Type=oneshot RemainAfterExit=true ExecStart=YOUR_COMMAND # beware, executable is run directly, not through a shell, check the man pages # systemd.service and systemd.unit for full syntax [Install] # target in which to start the service WantedBy=multi-user.target #WantedBy=graphical.target
When the service file is created, you should run the following commands
(as root
):
tux >
sudo
systemctl daemon-reloadtux >
sudo
systemctl enable before
Every time you modify the service file, you need to run:
tux >
sudo
systemctl daemon-reload
On a traditional System V init system it is not always possible to clearly assign a process to the service that spawned it. Some services, such as Apache, spawn a lot of third-party processes (for example CGI or Java processes), which themselves spawn more processes. This makes a clear assignment difficult or even impossible. Additionally, a service may not terminate correctly, leaving some children alive.
systemd solves this problem by placing each service into its own cgroup. cgroups are a kernel feature that allows aggregating processes and all their children into hierarchical organized groups. systemd names each cgroup after its service. Since a non-privileged process is not allowed to “leave” its cgroup, this provides an effective way to label all processes spawned by a service with the name of the service.
To list all processes belonging to a service, use the command
systemd-cgls
. The result will look like the following
(shortened) example:
root #
systemd-cgls --no-pager
├─1 /usr/lib/systemd/systemd --switched-root --system --deserialize 20
├─user.slice
│ └─user-1000.slice
│ ├─session-102.scope
│ │ ├─12426 gdm-session-worker [pam/gdm-password]
│ │ ├─15831 gdm-session-worker [pam/gdm-password]
│ │ ├─15839 gdm-session-worker [pam/gdm-password]
│ │ ├─15858 /usr/lib/gnome-terminal-server
[...]
└─system.slice
├─systemd-hostnamed.service
│ └─17616 /usr/lib/systemd/systemd-hostnamed
├─cron.service
│ └─1689 /usr/sbin/cron -n
├─postfix.service
│ ├─ 1676 /usr/lib/postfix/master -w
│ ├─ 1679 qmgr -l -t fifo -u
│ └─15590 pickup -l -t fifo -u
├─sshd.service
│ └─1436 /usr/sbin/sshd -D
[...]
See Book “System Analysis and Tuning Guide”, Chapter 9 “Kernel Control Groups” for more information about cgroups.
As explained in Section 15.6.6, “Kernel Control Groups (cgroups)”, it is not always possible to assign a process to its parent service process in a System V init system. This makes it difficult to terminate a service and all of its children. Child processes that have not been terminated will remain as zombie processes.
systemd's concept of confining each service into a cgroup makes it possible
to clearly identify all child processes of a service and therefore allows
you to send a signal to each of these processes. Use systemctl
kill
to send signals to services. For a list of available signals
refer to man 7 signals
.
SIGTERM
to a Service
SIGTERM
is the default signal that is sent.
tux >
sudo
systemctl kill MY_SERVICE
Use the -s
option to specify the signal that should be
sent.
tux >
sudo
systemctl kill -s SIGNAL MY_SERVICE
By default the kill
command sends the signal to
all
processes of the specified cgroup. You can restrict
it to the control
or the main
process.
The latter is for example useful to force a service to reload its
configuration by sending SIGHUP
:
tux >
sudo
systemctl kill -s SIGHUP --kill-who=main MY_SERVICE
The D-Bus service is the message bus for communication between systemd
clients and the systemd manager that is running as pid 1. Even though
dbus
is a stand-alone daemon, it
is an integral part of the init infrastructure.
Terminating dbus
or restarting it
in the running system is similar to an attempt to terminate or restart pid
1. It will break systemd client/server communication and make most systemd
functions unusable.
Therefore, terminating or restarting
dbus
is neither recommended
nor supported.
Updating the dbus
or
dbus
-related packages requires a reboot. When in
doubt whether a reboot is necessary, run the sudo zypper ps
-s
. If dbus
appears among the listed
services, you need to reboot the system.
Keep in mind that dbus
is updated even when
automatic updates are configured to skip the packages that require reboot.
By default, systemd is not overly verbose. If a service was started
successfully, no output will be produced. In case of a failure, a short
error message will be displayed. However, systemctl
status
provides means to debug start-up and operation of a
service.
systemd comes with its own logging mechanism (“The Journal”)
that logs system messages. This allows you to display the service messages
together with status messages. The status
command works
similar to tail
and can also display the log messages in
different formats, making it a powerful debugging tool.
Whenever a service fails to start, use systemctl status
MY_SERVICE
to get a detailed error
message:
root #
systemctl start apache2 Job failed. See system journal and 'systemctl status' for details.root #
systemctl status apache2 Loaded: loaded (/usr/lib/systemd/system/apache2.service; disabled) Active: failed (Result: exit-code) since Mon, 04 Apr 2018 16:52:26 +0200; 29s ago Process: 3088 ExecStart=/usr/sbin/start_apache2 -D SYSTEMD -k start (code=exited, status=1/FAILURE) CGroup: name=systemd:/system/apache2.service Apr 04 16:52:26 g144 start_apache2[3088]: httpd2-prefork: Syntax error on line 205 of /etc/apache2/httpd.conf: Syntax error on li...alHost>
The default behavior of the status
subcommand is to
display the last ten messages a service issued. To change the number of
messages to show, use the
--lines=N
parameter:
tux >
sudo
systemctl status chronydtux >
sudo
systemctl --lines=20 status chronyd
To display a “live stream” of service messages, use the
--follow
option, which works like
tail
-f
:
tux >
sudo
systemctl --follow status chronyd
The --output=MODE
parameter
allows you to change the output format of service messages. The most
important modes available are:
short
The default format. Shows the log messages with a human readable time stamp.
verbose
Full output with all fields.
cat
Terse output without time stamps.
For more information on systemd refer to the following online resources:
Lennart Pöttering, one of the systemd authors, has written a series of blog entries (13 at the time of writing this chapter). Find them at http://0pointer.de/blog/projects.
SUSE® Linux Enterprise Desktop is available for 64-bit platforms. The developers have not ported all 32-bit applications to 64-bit systems. This chapter offers a brief overview of 32-bit support implementation on 64-bit SUSE Linux Enterprise Desktop platforms.
journalctl
: Query the systemd
Journal
When systemd
replaced traditional init scripts in SUSE Linux Enterprise 12
(see Chapter 15, The systemd
Daemon), it introduced its own logging system
called journal. There is no need to run a
syslog
based service anymore, as all system events
are written in the journal.
update-alternatives
: Managing Multiple Versions of Commands and FilesOften, there are several versions of the same tool installed on a system. To give administrators a choice and to make it possible to install and use different versions side by side, the alternatives system allows managing such versions consistently.
Linux offers the necessary networking tools and features for integration into all types of network structures. Network access using a network card can be configured with YaST. Manual configuration is also possible. In this chapter only the fundamental mechanisms and the relevant network configuration files are covered.
SUSE® Linux Enterprise Desktop supports printing with many types of printers, including remote network printers. Printers can be configured manually or with YaST. For configuration instructions, refer to Book “Deployment Guide”, Chapter 15 “Setting Up Hardware Components with YaST”, Section 15.3 “Se…
SUSE Linux Enterprise Desktop includes the X.org server, Wayland and the GNOME desktop. This chapter describes the configuration of the graphical user interface for all users.
FUSE is the acronym for file system in user space.
This means you can configure and mount a file system as an unprivileged
user. Normally, you need to be
root
for this task. FUSE alone is
a kernel module. Combined with plug-ins, it allows you to extend FUSE to
access almost all file systems like remote SSH connections, ISO images, and
more.
Although Linux is a monolithic kernel, it can be extended using kernel modules. These are special objects that can be inserted into the kernel and removed on demand. In practical terms, kernel modules make it possible to add and remove drivers and interfaces that are not included in the kernel itsel…
udev
The kernel can add or remove almost any device in a running system. Changes in the device state (whether a device is plugged in or removed) need to be propagated to user space. Devices need to be configured when they are plugged in and recognized. Users of a certain device need to be informed about …
This chapter starts with information about various software packages, the
virtual consoles and the keyboard layout. We talk about software components
like bash
,
cron
and
logrotate
, because they were
changed or enhanced during the last release cycles. Even if they are small
or considered of minor importance, users should change their default
behavior, because these components are often closely coupled with the
system. The chapter concludes with a section about language and
country-specific settings (I18N and L10N).
NetworkManager is the ideal solution for laptops and other portable computers. It supports state-of-the-art encryption types and standards for network connections, including connections to 802.1X protected networks. 802.1X is the “IEEE Standard for Local and Metropolitan Area Networks—Port-Based Net…
Power management is especially important on laptop computers, but is also useful on other systems. ACPI (Advanced Configuration and Power Interface) is available on all modern computers (laptops, desktops, and servers). Power management technologies require suitable hardware and BIOS routines. Most …
This chapter contains additional information on when SUSE Linux Enterprise Desktop is used in a virtual machine.
This chapter contains additional information about using SUSE Linux Enterprise with non-volatile main memory, also known as Persistent Memory, comprising one or more NVDIMMs.
SUSE® Linux Enterprise Desktop is available for 64-bit platforms. The developers have not ported all 32-bit applications to 64-bit systems. This chapter offers a brief overview of 32-bit support implementation on 64-bit SUSE Linux Enterprise Desktop platforms.
SUSE Linux Enterprise Desktop for the 64-bit platforms AMD64 and Intel 64 is designed so that existing 32-bit applications run in the 64-bit environment “out-of-the-box.” This support means that you can continue to use your preferred 32-bit applications without waiting for a corresponding 64-bit port to become available.
SUSE Linux Enterprise Desktop does not support compilation of 32-bit applications. It only offers runtime support for 32-bit binaries.
If an application is available for both 32-bit and 64-bit environments, installing both versions may cause problems. In such cases, decide on one version to install to avoid potential runtime errors.
An exception to this rule is PAM (pluggable authentication modules). SUSE Linux Enterprise Desktop uses PAM in the authentication process as a layer that mediates between user and application. Always install both PAM versions on 64-bit operating systems that also run 32-bit applications.
For correct execution, every application requires a range of libraries. Unfortunately, the names are identical for the 32-bit and 64-bit versions of these libraries. They must be differentiated from each other in another way.
To retain compatibility with 32-bit versions, 64-bit and
32-bit libraries are stored in the same location. The 32-bit
version of libc.so.6
is located under
/lib/libc.so.6
in both 32-bit and 64-bit
environments.
All 64-bit libraries and object files are located in directories called
lib64
. The 64-bit object files normally
found under /lib
and
/usr/lib
are now found under
/lib64
and /usr/lib64
. This means
that space is available for 32-bit libraries under /lib
and /usr/lib
, so the file name for both versions can
remain unchanged.
If the data content of 32-bit subdirectories under /lib
does not
depend on word size, they are not moved. This scheme conforms to LSB (Linux Standards Base)
and FHS (File System Hierarchy Standard).
The 64-bit kernels for AMD64/Intel 64 offer both a 64-bit and a 32-bit kernel ABI (application binary interface). The latter is identical to the ABI for the corresponding 32-bit kernel. This means that communication between both 32-bit and 64-bit applications with 64-bit kernels are identical.
The 32-bit system call emulation for 64-bit kernels does not support
all the APIs used by system programs. This depends on the platform. For this
reason, few applications, like lspci
, must be
compiled.
A 64-bit kernel can only load 64-bit kernel modules. You must compile 64-bit modules specifically for 64-bit kernels. It is not possible to use 32-bit kernel modules with 64-bit kernels.
Some applications require separate kernel-loadable modules. If you intend to use a 32-bit application in a 64-bit system environment, contact the provider of the application and SUSE. Make sure that the 64-bit version of the kernel-loadable module and the 32-bit compiled version of the kernel API are available for this module.
journalctl
: Query the systemd
Journal #Edit source
When systemd
replaced traditional init scripts in SUSE Linux Enterprise 12
(see Chapter 15, The systemd
Daemon), it introduced its own logging system
called journal. There is no need to run a
syslog
based service anymore, as all system events
are written in the journal.
The journal itself is a system service managed by systemd
. Its full name is
systemd-journald.service
. It collects and stores logging
data by maintaining structured indexed journals based on logging information
received from the kernel, user processes, standard input, and system service errors. The systemd-journald
service is on
by default:
tux >
sudo
systemctl status systemd-journald systemd-journald.service - Journal Service Loaded: loaded (/usr/lib/systemd/system/systemd-journald.service; static) Active: active (running) since Mon 2014-05-26 08:36:59 EDT; 3 days ago Docs: man:systemd-journald.service(8) man:journald.conf(5) Main PID: 413 (systemd-journal) Status: "Processing requests..." CGroup: /system.slice/systemd-journald.service └─413 /usr/lib/systemd/systemd-journald [...]
The journal stores log data in /run/log/journal/
by
default. Because the /run/
directory is volatile by
nature, log data is lost at reboot. To make the log data persistent, the
directory /var/log/journal/
must exist with correct
ownership and permissions so the systemd-journald service can store its
data. systemd
will create the directory for you—and switch to
persistent logging—if you do the following:
As root
, open /etc/systemd/journald.conf
for
editing.
root #
vi /etc/systemd/journald.conf
Uncomment the line containing Storage=
and change it to
[...] [Journal] Storage=persistent #Compress=yes [...]
Save the file and restart systemd-journald:
root #
systemctl restart systemd-journald
journalctl
Useful Switches #Edit source
This section introduces several common useful options to enhance the default
journalctl
behavior. All switches are described in the
journalctl
manual page, man 1
journalctl
.
To show all journal messages related to a specific executable, specify the full path to the executable:
tux >
sudo
journalctl /usr/lib/systemd/systemd
Shows only the most recent journal messages, and prints new log entries as they are added to the journal.
Prints the messages and jumps to the end of the journal, so that the latest entries are visible within the pager.
Prints the messages of the journal in reverse order, so that the latest entries are listed first.
Shows only kernel messages. This is equivalent to the field match
_TRANSPORT=kernel
(see
Section 17.3.3, “Filtering Based on Fields”).
Shows only messages for the specified systemd
unit. This is equivalent
to the field match
_SYSTEMD_UNIT=UNIT
(see
Section 17.3.3, “Filtering Based on Fields”).
tux >
sudo
journalctl -u apache2 [...] Jun 03 10:07:11 pinkiepie systemd[1]: Starting The Apache Webserver... Jun 03 10:07:12 pinkiepie systemd[1]: Started The Apache Webserver.
When called without switches, journalctl
shows the full
content of the journal, the oldest entries listed first. The output can be
filtered by specific switches and fields.
journalctl
can filter messages based on a specific
system boot. To list all available boots, run
tux >
sudo
journalctl --list-boots -1 097ed2cd99124a2391d2cffab1b566f0 Mon 2014-05-26 08:36:56 EDT—Fri 2014-05-30 05:33:44 EDT 0 156019a44a774a0bb0148a92df4af81b Fri 2014-05-30 05:34:09 EDT—Fri 2014-05-30 06:15:01 EDT
The first column lists the boot offset: 0
for the
current boot, -1
for the previous one,
-2
for the one prior to that, etc. The second column
contains the boot ID followed by the limiting time stamps of the specific
boot.
Show all messages from the current boot:
tux >
sudo
journalctl -b
If you need to see journal messages from the previous boot, add an offset parameter. The following example outputs the previous boot messages:
tux >
sudo
journalctl -b -1
Another way is to list boot messages based on the boot ID. For this purpose, use the _BOOT_ID field:
tux >
sudo
journalctl _BOOT_ID=156019a44a774a0bb0148a92df4af81b
You can filter the output of journalctl
by specifying
the starting and/or ending date. The date specification should be of the
format "2014-06-30 9:17:16". If the time part is omitted, midnight is
assumed. If seconds are omitted, ":00" is assumed. If the date part is
omitted, the current day is assumed. Instead of numeric expression, you can
specify the keywords "yesterday", "today", or "tomorrow". They refer to
midnight of the day before the current day, of the current day, or of the
day after the current day. If you specify "now", it refers to the current
time. You can also specify relative times prefixed with
-
or +
, referring to times before or
after the current time.
Show only new messages since now, and update the output continuously:
tux >
sudo
journalctl --since "now" -f
Show all messages since last midnight till 3:20am:
tux >
sudo
journalctl --since "today" --until "3:20"
You can filter the output of the journal by specific fields. The syntax of
a field to be matched is FIELD_NAME=MATCHED_VALUE
, such
as _SYSTEMD_UNIT=httpd.service
. You can specify multiple
matches in a single query to filter the output messages even more. See
man 7 systemd.journal-fields
for a list of default
fields.
Show messages produced by a specific process ID:
tux >
sudo
journalctl _PID=1039
Show messages belonging to a specific user ID:
# journalctl _UID=1000
Show messages from the kernel ring buffer (the same as
dmesg
produces):
tux >
sudo
journalctl _TRANSPORT=kernel
Show messages from the service's standard or error output:
tux >
sudo
journalctl _TRANSPORT=stdout
Show messages produced by a specified service only:
tux >
sudo
journalctl _SYSTEMD_UNIT=avahi-daemon.service
If two different fields are specified, only entries that match both expressions at the same time are shown:
tux >
sudo
journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=1488
If two matches refer to the same field, all entries matching either expression are shown:
tux >
sudo
journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service
You can use the '+' separator to combine two expressions in a logical 'OR'. The following example shows all messages from the Avahi service process with the process ID 1480 together with all messages from the D-Bus service:
tux >
sudo
journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=1480 + _SYSTEMD_UNIT=dbus.service
systemd
Errors #Edit source
This section introduces a simple example to illustrate how to find and fix
the error reported by systemd
during apache2
start-up.
Try to start the apache2 service:
# systemctl start apache2 Job for apache2.service failed. See 'systemctl status apache2' and 'journalctl -xn' for details.
Let us see what the service's status says:
tux >
sudo
systemctl status apache2 apache2.service - The Apache Webserver Loaded: loaded (/usr/lib/systemd/system/apache2.service; disabled) Active: failed (Result: exit-code) since Tue 2014-06-03 11:08:13 CEST; 7min ago Process: 11026 ExecStop=/usr/sbin/start_apache2 -D SYSTEMD -DFOREGROUND \ -k graceful-stop (code=exited, status=1/FAILURE)
The ID of the process causing the failure is 11026.
Show the verbose version of messages related to process ID 11026:
tux >
sudo
journalctl -o verbose _PID=11026 [...] MESSAGE=AH00526: Syntax error on line 6 of /etc/apache2/default-server.conf: [...] MESSAGE=Invalid command 'DocumenttRoot', perhaps misspelled or defined by a module [...]
Fix the typo inside /etc/apache2/default-server.conf
,
start the apache2 service, and print its status:
tux >
sudo
systemctl start apache2 && systemctl status apache2 apache2.service - The Apache Webserver Loaded: loaded (/usr/lib/systemd/system/apache2.service; disabled) Active: active (running) since Tue 2014-06-03 11:26:24 CEST; 4ms ago Process: 11026 ExecStop=/usr/sbin/start_apache2 -D SYSTEMD -DFOREGROUND -k graceful-stop (code=exited, status=1/FAILURE) Main PID: 11263 (httpd2-prefork) Status: "Processing requests..." CGroup: /system.slice/apache2.service ├─11263 /usr/sbin/httpd2-prefork -f /etc/apache2/httpd.conf -D [...] ├─11280 /usr/sbin/httpd2-prefork -f /etc/apache2/httpd.conf -D [...] ├─11281 /usr/sbin/httpd2-prefork -f /etc/apache2/httpd.conf -D [...] ├─11282 /usr/sbin/httpd2-prefork -f /etc/apache2/httpd.conf -D [...] ├─11283 /usr/sbin/httpd2-prefork -f /etc/apache2/httpd.conf -D [...] └─11285 /usr/sbin/httpd2-prefork -f /etc/apache2/httpd.conf -D [...]
The behavior of the systemd-journald service can be adjusted by modifying
/etc/systemd/journald.conf
. This section introduces
only basic option settings. For a complete file description, see
man 5 journald.conf
. Note that you need to restart the
journal for the changes to take effect with
tux >
sudo
systemctl restart systemd-journald
If the journal log data is saved to a persistent location (see
Section 17.1, “Making the Journal Persistent”), it uses up to 10% of the file
system the /var/log/journal
resides on. For example,
if /var/log/journal
is located on a 30 GB
/var
partition, the journal may use up to 3 GB of the
disk space. To change this limit, change (and uncomment) the
SystemMaxUse
option:
SystemMaxUse=50M
/dev/ttyX
#Edit source
You can forward the journal to a terminal device to inform you about system
messages on a preferred terminal screen, for example
/dev/tty12
. Change the following journald options to
ForwardToConsole=yes TTYPath=/dev/tty12
Journald is backward compatible with traditional syslog implementations
such as rsyslog
. Make sure the following is valid:
rsyslog is installed.
tux >
sudo
rpm -q rsyslog rsyslog-7.4.8-2.16.x86_64
rsyslog service is enabled.
tux >
sudo
systemctl is-enabled rsyslog enabled
Forwarding to syslog is enabled in
/etc/systemd/journald.conf
.
ForwardToSyslog=yes
systemd
Journal #Edit source
For an easy way of filtering the systemd journal (without dealing
with the journalctl syntax), you can use the YaST journal module. After
installing it with sudo zypper in yast2-journal
, start it
from YaST by selecting › . Alternatively, start it
from command line by entering sudo yast2 journal
.
The module displays the log entries in a table. The search box on top allows
you to search for entries that contain certain characters, similar to using
grep
. To filter the entries by date and time, unit, file,
or priority, click and set the respective
options.
You can view the journal with GNOME Logs.
Start it from the application menu. To view system log messages, it
needs to be run as root, for example with xdg-su
gnome-logs
. This command can be executed when pressing
Alt–F2.
update-alternatives
: Managing Multiple Versions of Commands and Files #Edit sourceOften, there are several versions of the same tool installed on a system. To give administrators a choice and to make it possible to install and use different versions side by side, the alternatives system allows managing such versions consistently.
On SUSE Linux Enterprise Desktop, some programs perform the same or similar tasks. For example,
if Java 1.7 and Java 1.8 are both installed on the system, the alternatives system script
(update-alternatives
) is called from inside the RPM package.
By default, the alternatives system will refer to version 1.8: Higher versions also have a
higher priority. However, the administrator can change the default and
can point the generic name to version 1.7.
The following terminology is used in this chapter:
The default /var/lib/rpm/alternatives
directory contains information
about the current state of alternatives.
The name of a specific file in the file system, which can be made accessible via a generic name using the alternatives system.
The default /etc/alternatives
directory containing symbolic links.
A name (for example, /usr/bin/edit
) that refers to
one file out of several available using the alternatives system.
A set of related symbolic links that can be updated as a group.
The link in a link group that determines how the other links in the group are configured.
A link in a link group controlled by the master link.
A file that is a reference to another file in the same file system. The alternatives system uses symbolic links in the alternatives directory to switch between versions of a file.
Symbolic links in the alternatives directory can be modified by the
administrator through the update-alternatives
command.
The alternatives system provides the update-alternatives
command to
create, remove, maintain, and show information about symbolic links.
While these symbolic links usually point to commands, they can also point
to JAR archives, man pages, and other files.
Examples in this chapter use commands and man pages, but they are also
applicable to other file types.
The alternatives system uses the alternatives directory to collect links to possible alternatives. When a new package with an alternative is installed, the new alternative is added to the system. Whether the new package's alternative is selected as the default depends on its priority and on the mode that is set. Usually, packages with a higher version also have a higher priority. The alternatives system can operate in two modes:
Automatic Mode. In this mode, the alternatives system ensures that the links in the group point to the highest priority alternatives appropriate for the group.
Manual Mode. In this mode, the alternatives system does not make any changes to the system administrator's settings.
For example, the java
command has the following link
hierarchy in the alternatives system:
By default, the update-alternatives
script is called
from inside an RPM package. When a package is installed or removed, the
script takes care of all its symbolic links.
But you can run it manually from the command line for:
displaying the current alternatives for a generic name.
changing the defaults of an alternative.
creating a set of related files for an alternative.
To retrieve the names of all configured alternatives, use:
tux >
ls /var/lib/alternatives
To get an overview of all configured alternatives and their values, use
tux >
sudo
update-alternatives --get-selections
asadmin auto /usr/bin/asadmin-2.7 awk auto /usr/bin/gawk chardetect auto /usr/bin/chardetect-3.6 dbus-launch auto /usr/bin/dbus-launch.x11 default-displaymanager auto /usr/lib/X11/displaymanagers/gdm [...]
The easiest way to check the alternatives is to follow the symbolic links of
your command.
For example, if you want to know what the java
command is referring to, use the following command:
tux >
readlink --canonicalize /usr/bin/java
/usr/lib64/jvm/jre-10-openjdk/bin/java
If you see the same path (in our example, it is
/usr/bin/java
),
there are no alternatives available for this command.
To see the full alternatives (including slaves), use the
--display
option:
tux >
sudo
update-alternatives --display java
java - auto mode link best version is /usr/lib64/jvm/jre-1.8.0-openjdk/bin/java link currently points to /usr/lib64/jvm/jre-1.8.0-openjdk/bin/java link java is /usr/bin/java slave java.1.gz is /usr/share/man/man1/java.1.gz slave jre is /usr/lib64/jvm/jre slave jre_exports is /usr/lib64/jvm-exports/jre slave keytool is /usr/bin/keytool slave keytool.1.gz is /usr/share/man/man1/keytool.1.gz slave orbd is /usr/bin/orbd slave orbd.1.gz is /usr/share/man/man1/orbd.1.gz [...]
By default, commands in /usr/bin
refer to the
alternatives directory with the highest priority. For example,
by default, the command java
shows the following
version number:
tux >
java -version
openjdk version "10.0.1" 2018-04-17 OpenJDK Runtime Environment (build 10.0.1+10-suse-lp150.1.11-x8664) OpenJDK 64-Bit Server VM (build 10.0.1+10-suse-lp150.1.11-x8664, mixed mode)
To change the default java
command to refer
to a previous version, run:
tux >
sudo
update-alternatives --config java
root's password: There are 2 choices for the alternative java (providing /usr/bin/java). Selection Path Priority Status ------------------------------------------------------------ * 0 /usr/lib64/jvm/jre-10-openjdk/bin/java 2005 auto mode 1 /usr/lib64/jvm/jre-1.8.0-openjdk/bin/java 1805 manual mode 2 /usr/lib64/jvm/jre-10-openjdk/bin/java 2005 manual mode 3 /usr/lib64/jvm/jre-11-openjdk/bin/java 0 manual mode Press <enter> to keep the current choice[*], or type selection number:
Depending on your system and installed versions, the exact Java version
number will be different.
After you have selected 1
, java
shows the following version number:
tux >
java -version
java version "1.8.0_171" OpenJDK Runtime Environment (IcedTea 3.8.0) (build 1.8.0_171-b11 suse-lp150.2.3.1-x86_64) OpenJDK 64-Bit Server VM (build 25.171-b11, mixed mode)
Also, keep in mind the following points:
When working in manual mode and installing another Java version, the alternatives system neither touches the links nor changes the generic name.
When working in automatic mode and installing another Java version, the alternatives system changes the Java master link and all slave links (as you can see in Section 18.4, “Viewing Details on Specific Alternatives”). To check the master-slave relationships, use:
tux >
sudo
update-alternatives --display java
This section describes how to set up custom alternatives on a system. The example makes the following assumptions:
There are two scripts, foo-2
and foo-3
,
with similar functionality.
The scripts are stored in the /usr/local/bin
directory to avoid any conflicts with the system tools in
/usr/bin
.
There is a master link foo
that points to either
foo-2
or foo-3
.
To provide alternatives on your system, follow these steps:
Copy your scripts into the /usr/local/bin
directory.
Make the scripts executable:
tux >
sudo
chmod +x /usr/local/bin/foo-{2,3}
Run update-alternatives
for both scripts:
tux >
sudo
update-alternatives --install \ /usr/local/bin/foo 1\ foo 2\ /usr/local/bin/foo-2 3\ 200 4tux >
sudo
update-alternatives --install \ /usr/local/bin/foo 1\ foo 2\ /usr/local/bin/foo-3 3\ 300 4
The options after --install
have the following meanings:
The generic name. To avoid confusion, this is usually the script name without any version numbers. | |
The name of the master link. Must be the same. | |
The path to the original script(s) located in
| |
The priority.
We give |
Check the master link:
tux >
sudo
update-alternatives --display foo
foo - auto mode link best version is /usr/local/bin/foo-3 link currently points to /usr/local/bin/foo-3 link foo is /usr/local/bin/foo /usr/local/bin/foo-2 - priority 200 /usr/local/bin/foo-3 - priority 300
After you completed the described steps, you can use the master link
/usr/local/bin/foo
.
If needed, you can install additional alternatives. To remove an alternative, use the following command:
tux >
sudo
update-alternatives --remove foo /usr/local/bin/foo-2
After this script has been removed, the alternatives system for the foo group looks like this:
tux >
sudo
update-alternatives --display foo
foo - auto mode link best version is /usr/local/bin/foo-3 link currently points to /usr/local/bin/foo-3 link foo is /usr/local/bin/foo /usr/local/bin/foo-3 - priority 300
If you have alternatives, the script itself is not enough. Most commands are not completely stand-alone: They usually ship with additional files, such as extensions, configurations, or man pages. To create alternatives which are dependent on a master link, use slave alternatives.
Let us assume we want to extend our example in Section 18.6, “Installing Custom Alternatives” and provide man pages and configuration files:
Two man pages, foo-2.1.gz
and foo-3.1.gz
stored in the /usr/local/man/man1
directory.
Two configuration files, foo-2.conf
and
foo-3.conf
, stored in /etc
.
Follow these steps to add the additional files to your alternatives:
Copy the configuration files into /etc
:
tux >
sudo
cp foo-{2,3}.conf /etc
Copy the man pages into the /usr/local/man/man1
directory:
tux >
sudo
cp foo-{2,3}.1.gz /usr/local/man/man1/
Add the slave links to the main scripts with the --slave
option:
tux >
sudo
update-alternatives --install \ /usr/local/bin/foo foo /usr/local/bin/foo-2 200 \ --slave /usr/local/man/man1/foo.1.gz \ foo.1.gz \ /usr/local/man/man1/foo-2.1.gz \ --slave /etc/foo.conf \ foo.conf \ /etc/foo-2.conf
tux >
sudo
update-alternatives --install \ /usr/local/bin/foo foo /usr/local/bin/foo-3 300 \ --slave /usr/local/man/man1/foo.1.gz \ foo.1.gz \ /usr/local/man/man1/foo-3.1.gz \ --slave /etc/foo.conf \ foo.conf \ /etc/foo-3.conf
Check the master link:
foo - auto mode link best version is /usr/local/bin/foo-3 link currently points to /usr/local/bin/foo-3 link foo is /usr/local/bin/foo slave foo.1.gz is /usr/local/man/man1/foo.1.gz slave foo.conf is /etc/foo.conf /usr/local/bin/foo-2 - priority 200 slave foo.1.gz: /usr/local/man/man1/foo-2.1.gz slave foo.conf: /etc/foo-2.conf /usr/local/bin/foo-3 - priority 300 slave foo.1.gz: /usr/local/man/man1/foo-3.1.gz slave foo.conf: /etc/foo-3.conf
If you change the links with update-alternatives --config foo
to foo-2
, then all slave links will change as well.
Linux offers the necessary networking tools and features for integration into all types of network structures. Network access using a network card can be configured with YaST. Manual configuration is also possible. In this chapter only the fundamental mechanisms and the relevant network configuration files are covered.
Linux and other Unix operating systems use the TCP/IP protocol. It is not a single network protocol, but a family of network protocols that offer various services. The protocols listed in Several Protocols in the TCP/IP Protocol Family, are provided for exchanging data between two machines via TCP/IP. Networks combined by TCP/IP, comprising a worldwide network, are also called “the Internet.”
RFC stands for Request for Comments. RFCs are documents that describe various Internet protocols and implementation procedures for the operating system and its applications. The RFC documents describe the setup of Internet protocols. For more information about RFCs, see https://datatracker.ietf.org/.
Transmission Control Protocol: a connection-oriented secure protocol. The data to transmit is first sent by the application as a stream of data and converted into the appropriate format by the operating system. The data arrives at the respective application on the destination host in the original data stream format it was initially sent. TCP determines whether any data has been lost or jumbled during the transmission. TCP is implemented wherever the data sequence matters.
User Datagram Protocol: a connectionless, insecure protocol. The data to transmit is sent in the form of packets generated by the application. The order in which the data arrives at the recipient is not guaranteed and data loss is possible. UDP is suitable for record-oriented applications. It features a smaller latency period than TCP.
Internet Control Message Protocol: This is not a protocol for the end user, but a special control protocol that issues error reports and can control the behavior of machines participating in TCP/IP data transfer. In addition, it provides a special echo mode that can be viewed using the program ping.
Internet Group Management Protocol: This protocol controls machine behavior when implementing IP multicast.
As shown in Figure 19.1, “Simplified Layer Model for TCP/IP”, data exchange takes place in different layers. The actual network layer is the insecure data transfer via IP (Internet protocol). On top of IP, TCP (transmission control protocol) guarantees, to a certain extent, security of the data transfer. The IP layer is supported by the underlying hardware-dependent protocol, such as Ethernet.
The diagram provides one or two examples for each layer. The layers are ordered according to abstraction levels. The lowest layer is very close to the hardware. The uppermost layer, however, is almost a complete abstraction from the hardware. Every layer has its own special function. The special functions of each layer are mostly implicit in their description. The data link and physical layers represent the physical network used, such as Ethernet.
Almost all hardware protocols work on a packet-oriented basis. The data to transmit is collected into packets (it cannot be sent all at once). The maximum size of a TCP/IP packet is approximately 64 KB. Packets are normally quite smaller, as the network hardware can be a limiting factor. The maximum size of a data packet on an Ethernet is about fifteen hundred bytes. The size of a TCP/IP packet is limited to this amount when the data is sent over an Ethernet. If more data is transferred, more data packets need to be sent by the operating system.
For the layers to serve their designated functions, additional information regarding each layer must be saved in the data packet. This takes place in the header of the packet. Every layer attaches a small block of data, called the protocol header, to the front of each emerging packet. A sample TCP/IP data packet traveling over an Ethernet cable is illustrated in Figure 19.2, “TCP/IP Ethernet Packet”. The proof sum is located at the end of the packet, not at the beginning. This simplifies things for the network hardware.
When an application sends data over the network, the data passes through each layer, all implemented in the Linux kernel except the physical layer. Each layer is responsible for preparing the data so it can be passed to the next layer. The lowest layer is ultimately responsible for sending the data. The entire procedure is reversed when data is received. Like the layers of an onion, in each layer the protocol headers are removed from the transported data. Finally, the transport layer is responsible for making the data available for use by the applications at the destination. In this manner, one layer only communicates with the layer directly above or below it. For applications, it is irrelevant whether data is transmitted via a 100 Mbit/s FDDI network or via a 56-Kbit/s modem line. Likewise, it is irrelevant for the data line which kind of data is transmitted, as long as packets are in the correct format.
The discussion in this section is limited to IPv4 networks. For information about IPv6 protocol, the successor to IPv4, refer to Section 19.2, “IPv6—The Next Generation Internet”.
Every computer on the Internet has a unique 32-bit address. These 32 bits (or 4 bytes) are normally written as illustrated in the second row in Example 19.1, “Writing IP Addresses”.
IP Address (binary): 11000000 10101000 00000000 00010100 IP Address (decimal): 192. 168. 0. 20
In decimal form, the four bytes are written in the decimal number system, separated by periods. The IP address is assigned to a host or a network interface. It can be used only once throughout the world. There are exceptions to this rule, but these are not relevant to the following passages.
The points in IP addresses indicate the hierarchical system. Until the 1990s, IP addresses were strictly categorized in classes. However, this system proved too inflexible and was discontinued. Now, classless routing (CIDR, classless interdomain routing) is used.
Netmasks are used to define the address range of a subnet. If two hosts are in the same subnet, they can reach each other directly. If they are not in the same subnet, they need the address of a gateway that handles all the traffic for the subnet. To check if two IP addresses are in the same subnet, simply “AND” both addresses with the netmask. If the result is identical, both IP addresses are in the same local network. If there are differences, the remote IP address, and thus the remote interface, can only be reached over a gateway.
To understand how the netmask works, look at
Example 19.2, “Linking IP Addresses to the Netmask”. The netmask consists of 32 bits
that identify how much of an IP address belongs to the network. All those
bits that are 1
mark the corresponding bit in the IP
address as belonging to the network. All bits that are 0
mark bits inside the subnet. This means that the more bits are
1
, the smaller the subnet is. Because the netmask always
consists of several successive 1
bits, it is also
possible to count the number of bits in the netmask. In
Example 19.2, “Linking IP Addresses to the Netmask” the first net with 24 bits could
also be written as 192.168.0.0/24
.
IP address (192.168.0.20): 11000000 10101000 00000000 00010100 Netmask (255.255.255.0): 11111111 11111111 11111111 00000000 --------------------------------------------------------------- Result of the link: 11000000 10101000 00000000 00000000 In the decimal system: 192. 168. 0. 0 IP address (213.95.15.200): 11010101 10111111 00001111 11001000 Netmask (255.255.255.0): 11111111 11111111 11111111 00000000 --------------------------------------------------------------- Result of the link: 11010101 10111111 00001111 00000000 In the decimal system: 213. 95. 15. 0
To give another example: all machines connected with the same Ethernet cable are usually located in the same subnet and are directly accessible. Even when the subnet is physically divided by switches or bridges, these hosts can still be reached directly.
IP addresses outside the local subnet can only be reached if a gateway is configured for the target network. In the most common case, there is only one gateway that handles all traffic that is external. However, it is also possible to configure several gateways for different subnets.
If a gateway has been configured, all external IP packets are sent to the appropriate gateway. This gateway then attempts to forward the packets in the same manner—from host to host—until it reaches the destination host or the packet's TTL (time to live) expires.
This is the netmask AND any address in the network, as shown in
Example 19.2, “Linking IP Addresses to the Netmask” under Result
.
This address cannot be assigned to any hosts.
This could be paraphrased as: “Access all hosts in this subnet.” To generate this, the netmask is inverted in binary form and linked to the base network address with a logical OR. The above example therefore results in 192.168.0.255. This address cannot be assigned to any hosts.
The address 127.0.0.1
is
assigned to the “loopback device” on each host. A
connection can be set up to your own machine with this address and with
all addresses from the complete
127.0.0.0/8
loopback network
as defined with IPv4. With IPv6 there is only one loopback address
(::1
).
Because IP addresses must be unique all over the world, you cannot select random addresses. There are three address domains to use if you want to set up a private IP-based network. These cannot get any connection from the rest of the Internet, because they cannot be transmitted over the Internet. These address domains are specified in RFC 1597 and listed in Table 19.1, “Private IP Address Domains”.
Network/Netmask |
Domain |
---|---|
|
|
|
|
|
|
Because of the emergence of the World Wide Web (WWW), the Internet has experienced explosive growth, with an increasing number of computers communicating via TCP/IP in the past fifteen years. Since Tim Berners-Lee at CERN (http://public.web.cern.ch) invented the WWW in 1990, the number of Internet hosts has grown from a few thousand to about a hundred million.
As mentioned, an IPv4 address consists of only 32 bits. Also, quite a few IP addresses are lost—they cannot be used because of the way in which networks are organized. The number of addresses available in your subnet is two to the power of the number of bits, minus two. A subnet has, for example, 2, 6, or 14 addresses available. To connect 128 hosts to the Internet, for example, you need a subnet with 256 IP addresses, from which only 254 are usable, because two IP addresses are needed for the structure of the subnet itself: the broadcast and the base network address.
Under the current IPv4 protocol, DHCP or NAT (network address translation) are the typical mechanisms used to circumvent the potential address shortage. Combined with the convention to keep private and public address spaces separate, these methods can certainly mitigate the shortage. The problem with them lies in their configuration, which is a chore to set up and a burden to maintain. To set up a host in an IPv4 network, you need several address items, such as the host's own IP address, the subnetmask, the gateway address and maybe a name server address. All these items need to be known and cannot be derived from somewhere else.
With IPv6, both the address shortage and the complicated configuration should be a thing of the past. The following sections tell more about the improvements and benefits brought by IPv6 and about the transition from the old protocol to the new one.
The most important and most visible improvement brought by the newer protocol is the enormous expansion of the available address space. An IPv6 address is made up of 128 bit values instead of the traditional 32 bits. This provides for as many as several quadrillion IP addresses.
However, IPv6 addresses are not only different from their predecessors with regard to their length. They also have a different internal structure that may contain more specific information about the systems and the networks to which they belong. More details about this are found in Section 19.2.2, “Address Types and Structure”.
The following is a list of other advantages of the newer protocol:
IPv6 makes the network “plug and play” capable, which means that a newly set up system integrates into the (local) network without any manual configuration. The new host uses its automatic configuration mechanism to derive its own address from the information made available by the neighboring routers, relying on a protocol called the neighbor discovery (ND) protocol. This method does not require any intervention on the administrator's part and there is no need to maintain a central server for address allocation—an additional advantage over IPv4, where automatic address allocation requires a DHCP server.
Nevertheless if a router is connected to a switch, the router should
send periodic advertisements with flags telling the hosts of a network
how they should interact with each other. For more information, see
RFC 2462 and the radvd.conf(5)
man page, and
RFC 3315.
IPv6 makes it possible to assign several addresses to one network interface at the same time. This allows users to access several networks easily, something that could be compared with the international roaming services offered by mobile phone companies. When you take your mobile phone abroad, the phone automatically logs in to a foreign service when it enters the corresponding area, so you can be reached under the same number everywhere and can place an outgoing call, as you would in your home area.
With IPv4, network security is an add-on function. IPv6 includes IPsec as one of its core features, allowing systems to communicate over a secure tunnel to avoid eavesdropping by outsiders on the Internet.
Realistically, it would be impossible to switch the entire Internet from IPv4 to IPv6 at one time. Therefore, it is crucial that both protocols can coexist not only on the Internet, but also on one system. This is ensured by compatible addresses (IPv4 addresses can easily be translated into IPv6 addresses) and by using several tunnels. See Section 19.2.3, “Coexistence of IPv4 and IPv6”. Also, systems can rely on a dual stack IP technique to support both protocols at the same time, meaning that they have two network stacks that are completely separate, such that there is no interference between the two protocol versions.
With IPv4, some services, such as SMB, need to broadcast their packets to all hosts in the local network. IPv6 allows a much more fine-grained approach by enabling servers to address hosts through multicasting, that is by addressing several hosts as parts of a group. This is different from addressing all hosts through broadcasting or each host individually through unicasting. Which hosts are addressed as a group may depend on the concrete application. There are some predefined groups to address all name servers (the all name servers multicast group), for example, or all routers (the all routers multicast group).
As mentioned, the current IP protocol has two major limitations: there is an increasing shortage of IP addresses, and configuring the network and maintaining the routing tables is becoming a more complex and burdensome task. IPv6 solves the first problem by expanding the address space to 128 bits. The second one is mitigated by introducing a hierarchical address structure combined with sophisticated techniques to allocate network addresses, and multihoming (the ability to assign several addresses to one device, giving access to several networks).
When dealing with IPv6, it is useful to know about three different types of addresses:
Addresses of this type are associated with exactly one network interface. Packets with such an address are delivered to only one destination. Accordingly, unicast addresses are used to transfer packets to individual hosts on the local network or the Internet.
Addresses of this type relate to a group of network interfaces. Packets with such an address are delivered to all destinations that belong to the group. Multicast addresses are mainly used by certain network services to communicate with certain groups of hosts in a well-directed manner.
Addresses of this type are related to a group of interfaces. Packets with such an address are delivered to the member of the group that is closest to the sender, according to the principles of the underlying routing protocol. Anycast addresses are used to make it easier for hosts to find out about servers offering certain services in the given network area. All servers of the same type have the same anycast address. Whenever a host requests a service, it receives a reply from the server with the closest location, as determined by the routing protocol. If this server should fail for some reason, the protocol automatically selects the second closest server, then the third one, and so forth.
An IPv6 address is made up of eight four-digit fields, each representing 16
bits, written in hexadecimal notation. They are separated by colons
(:
). Any leading zero bytes within a given field may be
dropped, but zeros within the field or at its end may not. Another
convention is that more than four consecutive zero bytes may be collapsed
into a double colon. However, only one such ::
is
allowed per address. This kind of shorthand notation is shown in
Example 19.3, “Sample IPv6 Address”, where all three lines represent the
same address.
fe80 : 0000 : 0000 : 0000 : 0000 : 10 : 1000 : 1a4 fe80 : 0 : 0 : 0 : 0 : 10 : 1000 : 1a4 fe80 : : 10 : 1000 : 1a4
Each part of an IPv6 address has a defined function. The first bytes form
the prefix and specify the type of address. The center part is the network
portion of the address, but it may be unused. The end of the address forms
the host part. With IPv6, the netmask is defined by indicating the length
of the prefix after a slash at the end of the address. An address, as shown
in Example 19.4, “IPv6 Address Specifying the Prefix Length”, contains the information that
the first 64 bits form the network part of the address and the last 64 form
its host part. In other words, the 64
means that the
netmask is filled with 64 1-bit values from the left. As with IPv4, the IP
address is combined with AND with the values from the netmask to determine
whether the host is located in the same subnet or in another one.
fe80::10:1000:1a4/64
IPv6 knows about several predefined types of prefixes. Some are shown in Various IPv6 Prefixes.
00
IPv4 addresses and IPv4 over IPv6 compatibility addresses. These are used to maintain compatibility with IPv4. Their use still requires a router able to translate IPv6 packets into IPv4 packets. Several special addresses, such as the one for the loopback device, have this prefix as well.
2
or
3
as the
first digit
Aggregatable global unicast addresses. As is the case with IPv4, an
interface can be assigned to form part of a certain subnet. Currently,
there are the following address spaces:
2001::/16
(production quality
address space) and 2002::/16
(6to4 address space).
fe80::/10
Link-local addresses. Addresses with this prefix should not be routed and should therefore only be reachable from within the same subnet.
fec0::/10
Site-local addresses. These may be routed, but only within the network
of the organization to which they belong. In effect, they are the IPv6
equivalent of the current private network address space, such as
10.x.x.x
.
ff
These are multicast addresses.
A unicast address consists of three basic components:
The first part (which also contains one of the prefixes mentioned above) is used to route packets through the public Internet. It includes information about the company or institution that provides the Internet access.
The second part contains routing information about the subnet to which to deliver the packet.
The third part identifies the interface to which to deliver the packet.
This also allows for the MAC to form part of the address. Given that the
MAC is a globally unique, fixed identifier coded into the device by the
hardware maker, the configuration procedure is substantially simplified.
In fact, the first 64 address bits are consolidated to form the
EUI-64
token, with the last 48 bits taken from the
MAC, and the remaining 24 bits containing special information about the
token type. This also makes it possible to assign an
EUI-64
token to interfaces that do not have a MAC,
such as those based on PPP.
On top of this basic structure, IPv6 distinguishes between five different types of unicast addresses:
::
(unspecified) This address is used by the host as its source address when the interface is initialized for the first time (at which point, the address cannot yet be determined by other means).
::1
(loopback) The address of the loopback device.
The IPv6 address is formed by the IPv4 address and a prefix consisting of 96 zero bits. This type of compatibility address is used for tunneling (see Section 19.2.3, “Coexistence of IPv4 and IPv6”) to allow IPv4 and IPv6 hosts to communicate with others operating in a pure IPv4 environment.
This type of address specifies a pure IPv4 address in IPv6 notation.
There are two address types for local use:
This type of address can only be used in the local subnet. Packets
with a source or target address of this type should not be routed to
the Internet or other subnets. These addresses contain a special
prefix (fe80::/10
) and the
interface ID of the network card, with the middle part consisting of
zero bytes. Addresses of this type are used during automatic
configuration to communicate with other hosts belonging to the same
subnet.
Packets with this type of address may be routed to other subnets, but
not to the wider Internet—they must remain inside the
organization's own network. Such addresses are used for intranets and
are an equivalent of the private address space defined by IPv4. They
contain a special prefix
(fec0::/10
), the interface
ID, and a 16 bit field specifying the subnet ID. Again, the rest is
filled with zero bytes.
As a completely new feature introduced with IPv6, each network interface normally gets several IP addresses, with the advantage that several networks can be accessed through the same interface. One of these networks can be configured completely automatically using the MAC and a known prefix with the result that all hosts on the local network can be reached when IPv6 is enabled (using the link-local address). With the MAC forming part of it, any IP address used in the world is unique. The only variable parts of the address are those specifying the site topology and the public topology, depending on the actual network in which the host is currently operating.
For a host to go back and forth between different networks, it needs at least two addresses. One of them, the home address, not only contains the interface ID but also an identifier of the home network to which it normally belongs (and the corresponding prefix). The home address is a static address and, as such, it does not normally change. Still, all packets destined to the mobile host can be delivered to it, regardless of whether it operates in the home network or somewhere outside. This is made possible by the completely new features introduced with IPv6, such as stateless autoconfiguration and neighbor discovery. In addition to its home address, a mobile host gets one or more additional addresses that belong to the foreign networks where it is roaming. These are called care-of addresses. The home network has a facility that forwards any packets destined to the host when it is roaming outside. In an IPv6 environment, this task is performed by the home agent, which takes all packets destined to the home address and relays them through a tunnel. On the other hand, those packets destined to the care-of address are directly transferred to the mobile host without any special detours.
The migration of all hosts connected to the Internet from IPv4 to IPv6 is a gradual process. Both protocols will coexist for some time to come. The coexistence on one system is guaranteed where there is a dual stack implementation of both protocols. That still leaves the question of how an IPv6 enabled host should communicate with an IPv4 host and how IPv6 packets should be transported by the current networks, which are predominantly IPv4-based. The best solutions offer tunneling and compatibility addresses (see Section 19.2.2, “Address Types and Structure”).
IPv6 hosts that are more or less isolated in the (worldwide) IPv4 network can communicate through tunnels: IPv6 packets are encapsulated as IPv4 packets to move them across an IPv4 network. Such a connection between two IPv4 hosts is called a tunnel. To achieve this, packets must include the IPv6 destination address (or the corresponding prefix) and the IPv4 address of the remote host at the receiving end of the tunnel. A basic tunnel can be configured manually according to an agreement between the hosts' administrators. This is also called static tunneling.
However, the configuration and maintenance of static tunnels is often too labor-intensive to use them for daily communication needs. Therefore, IPv6 provides for three different methods of dynamic tunneling:
IPv6 packets are automatically encapsulated as IPv4 packets and sent over an IPv4 network capable of multicasting. IPv6 is tricked into seeing the whole network (Internet) as a huge local area network (LAN). This makes it possible to determine the receiving end of the IPv4 tunnel automatically. However, this method does not scale very well and is also hampered because IP multicasting is far from widespread on the Internet. Therefore, it only provides a solution for smaller corporate or institutional networks where multicasting can be enabled. The specifications for this method are laid down in RFC 2529.
With this method, IPv4 addresses are automatically generated from IPv6 addresses, enabling isolated IPv6 hosts to communicate over an IPv4 network. However, several problems have been reported regarding the communication between those isolated IPv6 hosts and the Internet. The method is described in RFC 3056.
This method relies on special servers that provide dedicated tunnels for IPv6 hosts. It is described in RFC 3053.
To configure IPv6, you normally do not need to make any changes on the
individual workstations. IPv6 is enabled by default. To disable or enable
IPv6 on an installed system, use the YaST modprobe
-i ipv6
as
root
. It is impossible to unload
the IPv6 module after it has been loaded.
Because of the autoconfiguration concept of IPv6, the network card is assigned an address in the link-local network. Normally, no routing table management takes place on a workstation. The network routers can be queried by the workstation, using the router advertisement protocol, for what prefix and gateways should be implemented. The radvd program can be used to set up an IPv6 router. This program informs the workstations which prefix to use for the IPv6 addresses and which routers. Alternatively, use zebra/quagga for automatic configuration of both addresses and routing.
For information about how to set up various types of tunnels using the
/etc/sysconfig/network
files, see the man page of
ifcfg-tunnel
(man ifcfg-tunnel
).
The above overview does not cover the topic of IPv6 comprehensively. For a more in-depth look at the newer protocol, refer to the following online documentation and books:
The starting point for everything about IPv6.
All information needed to start your own IPv6 network.
The list of IPv6-enabled products.
Here, find the Linux IPv6-HOWTO and many links related to the topic.
The fundamental RFC about IPv6.
A book describing all the important aspects of the topic is IPv6 Essentials by Silvia Hagen (ISBN 0-596-00125-8).
DNS assists in assigning an IP address to one or more names and assigning a name to an IP address. In Linux, this conversion is usually carried out by a special type of software known as bind. The machine that takes care of this conversion is called a name server. The names make up a hierarchical system in which each name component is separated by a period. The name hierarchy is, however, independent of the IP address hierarchy described above.
Consider a complete name, such as
jupiter.example.com
, written in the
format hostname.domain
. A full
name, called a fully qualified domain name (FQDN),
consists of a host name and a domain name
(example.com
). The latter
also includes the top level domain or TLD
(com
).
TLD assignment has become quite confusing for historical reasons.
Traditionally, three-letter domain names are used in the USA. In the rest of
the world, the two-letter ISO national codes are the standard. In addition
to that, longer TLDs were introduced in 2000 that represent certain spheres
of activity (for example, .info
,
.name
,
.museum
).
In the early days of the Internet (before 1990), the file
/etc/hosts
was used to store the names of all the
machines represented over the Internet. This quickly proved to be
impractical in the face of the rapidly growing number of computers connected
to the Internet. For this reason, a decentralized database was developed to
store the host names in a widely distributed manner. This database, similar
to the name server, does not have the data pertaining to all hosts in the
Internet readily available, but can dispatch requests to other name servers.
The top of the hierarchy is occupied by root name servers. These root name servers manage the top level domains and are run by the Network Information Center (NIC). Each root name server knows about the name servers responsible for a given top level domain. Information about top level domain NICs is available at http://www.internic.net.
DNS can do more than resolve host names. The name server also knows which host is receiving e-mails for an entire domain—the mail exchanger (MX).
For your machine to resolve an IP address, it must know about at least one name server and its IP address. Easily specify such a name server using YaST.
The protocol whois
is closely related to DNS. With this
program, quickly find out who is responsible for a given domain.
The .local
top level domain is treated as link-local
domain by the resolver. DNS requests are send as multicast DNS requests
instead of normal DNS requests. If you already use the
.local
domain in your name server configuration, you
must switch this option off in /etc/host.conf
. For
more information, see the host.conf
manual page.
To switch off MDNS during installation, use
nomdns=1
as a boot parameter.
For more information on multicast DNS, see http://www.multicastdns.org.
There are many supported networking types on Linux. Most of them use different device names and the configuration files are spread over several locations in the file system. For a detailed overview of the aspects of manual network configuration, see Section 19.6, “Configuring a Network Connection Manually”.
On SUSE Linux Enterprise Desktop, where NetworkManager is active by default, all network cards are configured. If NetworkManager is not active, only the first interface with link up (with a network cable connected) is automatically configured. Additional hardware can be configured any time on the installed system. The following sections describe the network configuration for all types of network connections supported by SUSE Linux Enterprise Desktop.
To configure your Ethernet or Wi-Fi/Bluetooth card in YaST, select
› . After starting the module, YaST displays the dialog with four tabs: , , and .The Section 19.4.1.1, “Configuring Global Networking Options”.
tab allows you to set general networking options such as the network setup method, IPv6, and general DHCP options. For more information, seeThe Section 19.4.1.3, “Configuring an Undetected Network Card”. To change the configuration of an already configured card, see Section 19.4.1.2, “Changing the Configuration of a Network Card”.
tab contains information about installed network interfaces and configurations. Any properly detected network card is listed with its name. You can manually configure new cards, remove or change their configuration in this dialog. To manually configure a card that was not automatically detected, seeThe Section 19.4.1.4, “Configuring Host Name and DNS”.
tab allows to set the host name of the machine and name the servers to be used. For more information, seeThe Section 19.4.1.5, “Configuring Routing” for more information.
tab is used for the configuration of routing. SeeThe
tab of the YaST module allows you to set important global networking options, such as the use of NetworkManager, IPv6 and DHCP client options. These settings are applicable for all network interfaces.
In the nm-applet
should be used to configure
network options and the ,
and tabs of the
module are disabled.
For more information on NetworkManager, see
Chapter 26, Using NetworkManager.
In the
choose whether to use the IPv6 protocol. It is possible to use IPv6 together with IPv4. By default, IPv6 is enabled. However, in networks not using IPv6 protocol, response times can be faster with IPv6 protocol disabled. To disable IPv6, deactivate . If IPv6 is disabled, the kernel no longer loads the IPv6 module automatically. This setting will be applied after reboot.In the
configure options for the DHCP client. The must be different for each DHCP client on a single network. If left empty, it defaults to the hardware address of the network interface. However, if you are running several virtual machines using the same network interface and, therefore, the same hardware address, specify a unique free-form identifier here.
The AUTO
to
send the current host name (that is the one defined in
/etc/HOSTNAME
). Make the option field empty for not
sending any host name.
If you do not want to change the default route according to the information from DHCP, deactivate
.To change the configuration of a network card, select a card from the list of the detected cards in
› in YaST and click . The dialog appears in which to adjust the card configuration using the , and tabs.You can set the IP address of the network card or the way its IP address is determined in the
tab of the dialog. Both IPv4 and IPv6 addresses are supported. The network card can have (which is useful for bonding devices), a (IPv4 or IPv6) or a assigned via or or both.If using
, select whether to use (for IPv4), (for IPv6) or .If possible, the first network card with link that is available during the installation is automatically configured to use automatic address setup via DHCP. On SUSE Linux Enterprise Desktop, where NetworkManager is active by default, all network cards are configured.
DHCP should also be used if you are using a DSL line but with no static IP assigned by the ISP (Internet Service Provider). If you decide to use DHCP, configure the details in
in the tab of the dialog of the YaST network card configuration module. If you have a virtual host setup where different hosts communicate through the same interface, an is necessary to distinguish them.DHCP is a good choice for client configuration but it is not ideal for server configuration. To set a static IP address, proceed as follows:
Select a card from the list of detected cards in the
tab of the YaST network card configuration module and click .In the
tab, choose .
Enter the /64
.
Optionally, you can enter a fully qualified /etc/hosts
configuration file.
Click
.To activate the configuration, click
.
During activation of a network interface, wicked
checks for a carrier and only applies the IP configuration when a link
has been detected. If you need to apply the configuration regardless of
the link status (for example, when you want to test a service listening to a
certain address), you can skip link detection by adding the variable
LINK_REQUIRED=no
to the configuration file of the
interface in /etc/sysconfig/network/ifcfg
.
Additionally, you can use the variable
LINK_READY_WAIT=5
to
specify the timeout for waiting for a link in seconds.
For more information about the ifcfg-*
configuration
files, refer to Section 19.6.2.5, “/etc/sysconfig/network/ifcfg-*
” and
man 5 ifcfg
.
If you use the static address, the name servers and default gateway are not configured automatically. To configure name servers, proceed as described in Section 19.4.1.4, “Configuring Host Name and DNS”. To configure a gateway, proceed as described in Section 19.4.1.5, “Configuring Routing”.
One network device can have multiple IP addresses.
These so-called aliases or labels, respectively, work with IPv4 only.
With IPv6 they will be ignored. Using iproute2
network
interfaces can have one or more addresses.
Using YaST to set additional addresses for your network card, proceed as follows:
Select a card from the list of detected cards in the
tab of the YaST dialog and click .In the
› tab, click .Enter
, , and . Do not include the interface name in the alias name.To activate the configuration, confirm the settings.
It is possible to change the device name of the network card when it is used. It is also possible to determine whether the network card should be identified by udev via its hardware (MAC) address or via the bus ID. The latter option is preferable in large servers to simplify hotplugging of cards. To set these options with YaST, proceed as follows:
Select a card from the list of detected cards in the
tab of the YaST dialog and click .Go to the
tab. The current device name is shown in . Click .Select whether udev should identify the card by its
or . The current MAC address and bus ID of the card are shown in the dialog.To change the device name, check the
option and edit the name.To activate the configuration, confirm the settings.
For some network cards, several kernel drivers may be available. If the card is already configured, YaST allows you to select a kernel driver to be used from a list of available suitable drivers. It is also possible to specify options for the kernel driver. To set these options with YaST, proceed as follows:
Select a card from the list of detected cards in the
tab of the YaST Network Settings module and click .Go to the
tab.
Select the kernel driver to be used in =
=VALUE. If more options
are used, they should be space-separated.
To activate the configuration, confirm the settings.
If you use the method with wicked
, you can configure
your device to either start during boot, on cable connection, on card
detection, manually, or never. To change device start-up, proceed as
follows:
In YaST select a card from the list of detected cards in
› and click .In the
tab, select the desired entry from .
Choose ifup
. Choose to not start
the device. The is similar to , but the interface does not shut down with the
systemctl stop network
command; the
network
service also cares about the
wicked
service if wicked
is active.
Use this if you use an NFS or iSCSI root file system.
To activate the configuration, confirm the settings.
On (diskless) systems where the root partition is mounted via network as an NFS share, you need to be careful when configuring the network device with which the NFS share is accessible.
When shutting down or rebooting the system, the default processing order is to turn off network connections, then unmount the root partition. With NFS root, this order causes problems as the root partition cannot be cleanly unmounted as the network connection to the NFS share is already not activated. To prevent the system from deactivating the relevant network device, open the network device configuration tab as described in Section 19.4.1.2.5, “Activating the Network Device” and choose in the pane.
You can set a maximum transmission unit (MTU) for the interface. MTU refers to the largest allowed packet size in bytes. A higher MTU brings higher bandwidth efficiency. However, large packets can block up a slow interface for some time, increasing the lag for further packets.
In YaST select a card from the list of detected cards in
› and click .In the
tab, select the desired entry from the list.To activate the configuration, confirm the settings.
Multifunction devices that support LAN, iSCSI, and FCoE are supported.
The YaST FCoE client (yast2 fcoe-client
) shows the
private flags in additional columns to allow the user to select the device
meant for FCoE. The YaST network module (yast2 lan
)
excludes “storage only devices” for network configuration.
In YaST select the InfiniBand device in
› and click .In the
tab, select one of the (IPoIB) modes: (default) or .To activate the configuration, confirm the settings.
For more information about InfiniBand, see
/usr/src/linux/Documentation/infiniband/ipoib.txt
.
Without having to perform the detailed firewall setup as described in
Book “Security and Hardening Guide”, Chapter 23 “Masquerading and Firewalls”, Section 23.4 “firewalld
”, you can determine the
basic firewall configuration for your device as part of the device setup.
Proceed as follows:
Open the YaST
› module. In the tab, select a card from the list of detected cards and click .Enter the
tab of the dialog.Determine the
to which your interface should be assigned. The following options are available:This option is available only if the firewall is disabled and the firewall does not run. Only use this option if your machine is part of a greater network that is protected by an outer firewall.
This option is available only if the firewall is enabled. The
firewall is running and the interface is automatically assigned to a
firewall zone. The zone which contains the keyword
any
or the external zone will be used for such an
interface.
The firewall is running, but does not enforce any rules to protect this interface. Use this option if your machine is part of a greater network that is protected by an outer firewall. It is also useful for the interfaces connected to the internal network, when the machine has more network interfaces.
A demilitarized zone is an additional line of defense in front of an internal network and the (hostile) Internet. Hosts assigned to this zone can be reached from the internal network and from the Internet, but cannot access the internal network.
The firewall is running on this interface and fully protects it against other—presumably hostile—network traffic. This is the default option.
To activate the configuration, confirm the settings.
If a network card is not detected correctly, the card is not included in the list of detected cards. If you are sure that your system includes a driver for your card, you can configure it manually. You can also configure special network device types, such as bridge, bond, TUN or TAP. To configure an undetected network card (or a special device) proceed as follows:
In the
› › dialog in YaST click .In the
dialog, set the of the interface from the available options and . If the network card is a USB device, activate the respective check box and exit this dialog with . Otherwise, you can define the kernel to be used for the card and its , if necessary.
In ethtool
options used by ifup
for
the interface. For information about available options, see the
ethtool
manual page.
If the option string starts with a
-
(for example, -K
INTERFACE_NAME rx on
), the second
word in the string is replaced with the current interface name. Otherwise
(for example, autoneg off speed 10
)
ifup
adds -s
INTERFACE_NAME
to the beginning.
Click
.Configure any needed options, such as the IP address, device activation or firewall zone for the interface in the Section 19.4.1.2, “Changing the Configuration of a Network Card”.
, , and tabs. For more information about the configuration options, seeIf you selected
as the device type of the interface, configure the wireless connection in the next dialog.To activate the new network configuration, confirm the settings.
If you did not change the network configuration during installation and the Ethernet card was already available, a host name was automatically generated for your computer and DHCP was activated. The same applies to the name service information your host needs to integrate into a network environment. If DHCP is used for network address setup, the list of domain name servers is automatically filled with the appropriate data. If a static setup is preferred, set these values manually.
To change the name of your computer and adjust the name server search list, proceed as follows:
Go to the
› tab in the module in YaST.Enter the
. Note that the host name is global and applies to all network interfaces.If you are using DHCP to get an IP address, the host name of your computer will be automatically set by the DHCP server. You should disable this behavior if you connect to different networks, because they may assign different host names and changing the host name at runtime may confuse the graphical desktop. To disable using DHCP to get an IP address deactivate
.
127.0.0.2
(loopback) IP address in
/etc/hosts
. This is a useful option if you want to
have the host name resolvable at all times, even without active network.
In /run/netconfig/resolv.conf
file) is modified.
If the netconfig
script which
merges the data defined statically (with YaST or in the configuration
files) with data obtained dynamically (from the DHCP client or
NetworkManager). This default policy is usually sufficient.
If the netconfig
is not allowed to modify the
/run/netconfig/resolv.conf
file. However, this file can be
edited manually.
If the eth* ppp?
will
first target all eth and then all ppp0-ppp9 interfaces. There are two
special policy values that indicate how to apply the static settings
defined in the /etc/sysconfig/network/config
file:
STATIC
The static settings need to be merged together with the dynamic settings.
STATIC_FALLBACK
The static settings are used only when no dynamic configuration is available.
For more information, see the man page of netconfig
(8)
(man 8 netconfig
).
Enter the
and fill in the list. Name servers must be specified by IP addresses, such as 192.168.1.116, not by host names. Names specified in the tab are domain names used for resolving host names without a specified domain. If more than one is used, separate domains with commas or white space.To activate the configuration, confirm the settings.
It is also possible to edit the host name using YaST from the command
line. The changes made by YaST take effect immediately (which is not the
case when editing the /etc/HOSTNAME
file manually). To
change the host name, use the following command:
root #
yast dns edit hostname=HOSTNAME
To change the name servers, use the following commands:
root #
yast dns edit nameserver1=192.168.1.116root #
yast dns edit nameserver2=192.168.1.117root #
yast dns edit nameserver3=192.168.1.118
To make your machine communicate with other machines and other networks, routing information must be given to make network traffic take the correct path. If DHCP is used, this information is automatically provided. If a static setup is used, this data must be added manually.
In YaST go to
› .Enter the IP address of the
(IPv4 and IPv6 if necessary). The default gateway matches every possible destination, but if a routing table entry exists that matches the required address, this will be used instead of the default route via the Default Gateway.
More entries can be entered in the -
. To
enter a default gateway into the table, use default
in
the field.
If more default routes are used, it is possible to specify the metric
option to determine which route has a higher priority. To specify the
metric option, enter - metric
NUMBER
in .
The lowest possible metric is 0. The route with the lowest metric has the
highest priority and is used as default. If the network device is
disconnected, its route will be removed and the next one will be used.
If the system is a router, enable
and in the as needed.To activate the configuration, confirm the settings.
NetworkManager is the ideal solution for laptops and other portable computers. With NetworkManager, you do not need to worry about configuring network interfaces and switching between networks when you are moving.
NetworkManager is only supported by SUSE for desktop workloads with SLED or Workstation extension. All server certifications are done with wicked as the network configuration tool, and using NetworkManager may invalidate them. NetworkManager is not supported by SUSE for server workloads.
wicked
#Edit source
However, NetworkManager is not a suitable solution for all cases, so you can
still choose between the wicked
controlled method for
managing network connections and NetworkManager. If you want to manage your
network connection with NetworkManager, enable NetworkManager in the YaST Network
Settings module as described in Section 26.2, “Enabling or Disabling NetworkManager” and
configure your network connections with NetworkManager. For a list of use cases
and a detailed description of how to configure and use NetworkManager, refer to
Chapter 26, Using NetworkManager.
Some differences between wicked and NetworkManager:
root
Privileges
If you use NetworkManager for network setup, you can easily switch, stop or
start your network connection at any time from within your desktop
environment using an applet. NetworkManager also makes it possible to change
and configure wireless card connections without requiring
root
privileges. For this reason, NetworkManager is the ideal
solution for a mobile workstation.
wicked
also provides some ways to switch, stop or
start the connection with or without user intervention, like
user-managed devices. However, this always requires root
privileges to change or configure a network device. This is often a
problem for mobile computing, where it is not possible to preconfigure
all the connection possibilities.
Both wicked
and NetworkManager can handle network
connections with a wireless network (with WEP, WPA-PSK, and
WPA-Enterprise access) and wired networks using DHCP and static
configuration. They also support connection through dial-up and VPN.
With NetworkManager you can also connect a mobile broadband (3G) modem
or set up a DSL connection, which is not possible with the traditional
configuration.
NetworkManager tries to keep your computer connected at all times using the
best connection available. If the network cable is accidentally
disconnected, it tries to reconnect. It can find the network with the
best signal strength from the list of your wireless connections and
automatically use it to connect. To get the same functionality with
wicked
, more configuration effort is required.
The individual network connection settings created with NetworkManager are
stored in configuration profiles. The system
connections configured with either NetworkManager or YaST are saved in
/etc/NetworkManager/system-connections/*
or in
/etc/sysconfig/network/ifcfg-*
. For GNOME, all
user-defined connections are stored in GConf.
In case no profile is configured, NetworkManager automatically creates one and
names it Auto $INTERFACE-NAME
. That is made in an
attempt to work without any configuration for as many cases as (securely)
possible. If the automatically created profiles do not suit your needs,
use the network connection configuration dialogs provided by GNOME to
modify them as desired. For more information, see
Section 26.3, “Configuring Network Connections”.
On centrally administered machines, certain NetworkManager features can be controlled or disabled with PolKit, for example if a user is allowed to modify administrator defined connections or if a user is allowed to define their own network configurations. To view or change the respective NetworkManager policies, start the graphical Book “Security and Hardening Guide”, Chapter 18 “Authorization with PolKit”.
tool for PolKit. In the tree on the left side, find them below the entry. For an introduction to PolKit and details on how to use it, refer toManual configuration of the network software should be the last alternative. Using YaST is recommended. However, this background information about the network configuration can also assist your work with YaST.
wicked
Network Configuration #Edit source
The tool and library called wicked
provides a new
framework for network configuration.
One of the challenges with traditional network interface management is that different layers of network management get jumbled together into one single script, or at most two different scripts. These scripts interact with each other in a way that is not well defined. This leads to unpredictable issues, obscure constraints and conventions, etc. Several layers of special hacks for a variety of different scenarios increase the maintenance burden. Address configuration protocols are being used that are implemented via daemons like dhcpcd, which interact rather poorly with the rest of the infrastructure. Funky interface naming schemes that require heavy udev support are introduced to achieve persistent identification of interfaces.
The idea of wicked is to decompose the problem in several ways. None of them is entirely novel, but trying to put ideas from different projects together is hopefully going to create a better solution overall.
One approach is to use a client/server model. This allows wicked to define standardized facilities for things like address configuration that are well integrated with the overall framework. For example, using a specific address configuration, the administrator may request that an interface should be configured via DHCP or IPv4 zeroconf. In this case, the address configuration service simply obtains the lease from its server and passes it on to the wicked server process that installs the requested addresses and routes.
The other approach to decomposing the problem is to enforce the layering aspect. For any type of network interface, it is possible to define a dbus service that configures the network interface's device layer—a VLAN, a bridge, a bonding, or a paravirtualized device. Common functionality, such as address configuration, is implemented by joint services that are layered on top of these device specific services without having to implement them specifically.
The wicked framework implements these two aspects by using a variety of dbus services, which get attached to a network interface depending on its type. Here is a rough overview of the current object hierarchy in wicked.
Each network interface is represented via a child object of
/org/opensuse/Network/Interfaces
. The name of the
child object is given by its ifindex. For example, the loopback interface,
which usually gets ifindex 1, is
/org/opensuse/Network/Interfaces/1
, the first
Ethernet interface registered is
/org/opensuse/Network/Interfaces/2
.
Each network interface has a “class” associated with it, which
is used to select the dbus interfaces it supports. By default, each network
interface is of class netif
, and
wickedd
will automatically
attach all interfaces compatible with this class. In the current
implementation, this includes the following interfaces:
Generic network interface functions, such as taking the link up or down, assigning an MTU, etc.
Address configuration services for DHCP, IPv4 zeroconf, etc.
Beyond this, network interfaces may require or offer special configuration
mechanisms. For an Ethernet device, for example, you should be able to
control the link speed, offloading of checksumming, etc. To achieve this,
Ethernet devices have a class of their own, called
netif-ethernet
, which is a subclass of
netif
. As a consequence, the dbus interfaces assigned to
an Ethernet interface include all the services listed above, plus the
org.opensuse.Network.Ethernet
service available only to objects belonging to the netif-ethernet
class.
Similarly, there exist classes for interface types like bridges, VLANs, bonds, or infinibands.
How do you interact with an interface like VLAN (which is really a virtual network interface that
sits on top of an Ethernet device) that needs to be created
first? For this, wicked defines factory
interfaces, such as
org.opensuse.Network.VLAN.Factory
. Such a factory
interface offers a single function that lets you create an interface of the
requested type. These factory interfaces are attached to the
/org/opensuse/Network/Interfaces
list node.
wicked
Architecture and Features #Edit source
The wicked
service comprises several parts as depicted
in Figure 19.4, “wicked
architecture”.
wicked
architecture #
wicked
currently supports the following:
Configuration file back-ends to parse SUSE style
/etc/sysconfig/network
files.
An internal configuration back-end to represent network interface configuration in XML.
Bring up and shutdown of “normal” network interfaces such as Ethernet or InfiniBand, VLAN, bridge, bonds, tun, tap, dummy, macvlan, macvtap, hsi, qeth, iucv, and wireless (currently limited to one wpa-psk/eap network) devices.
A built-in DHCPv4 client and a built-in DHCPv6 client.
The nanny daemon (enabled by default) helps to automatically bring up configured interfaces when the device is available (interface hotplugging) and set up the IP configuration when a link (carrier) is detected. See Section 19.6.1.3, “Nanny” for more information.
wicked
was implemented as a group of DBus services
that are integrated with systemd. So the usual
systemctl
commands will apply to
wicked
.
wicked
#Edit source
On SUSE Linux Enterprise, wicked
runs by default. If you want to check
what is currently enabled and whether it is running, call:
systemctl status network
If wicked
is enabled, you will see something along these
lines:
wicked.service - wicked managed network interfaces Loaded: loaded (/usr/lib/systemd/system/wicked.service; enabled) ...
In case something different is running (for example, NetworkManager) and you want to
switch to wicked
, first stop what is running and then
enable wicked
:
systemctl is-active network && \ systemctl stop network systemctl enable --force wicked
This enables the wicked services, creates the
network.service
to wicked.service
alias link, and starts the network at the next boot.
Starting the server process:
systemctl start wickedd
This starts wickedd
(the main server) and associated
supplicants:
/usr/lib/wicked/bin/wickedd-auto4 --systemd --foreground /usr/lib/wicked/bin/wickedd-dhcp4 --systemd --foreground /usr/lib/wicked/bin/wickedd-dhcp6 --systemd --foreground /usr/sbin/wickedd --systemd --foreground /usr/sbin/wickedd-nanny --systemd --foreground
Then bringing up the network:
systemctl start wicked
Alternatively use the network.service
alias:
systemctl start network
These commands are using the default or system configuration sources as
defined in /etc/wicked/client.xml
.
To enable debugging, set WICKED_DEBUG
in
/etc/sysconfig/network/config
, for example:
WICKED_DEBUG="all"
Or, to omit some:
WICKED_DEBUG="all,-dbus,-objectmodel,-xpath,-xml"
Use the client utility to display interface information for all interfaces or the interface specified with IFNAME:
wicked show all wicked show IFNAME
In XML output:
wicked show-xml all wicked show-xml IFNAME
Bringing up one interface:
wicked ifup eth0 wicked ifup wlan0 ...
Because there is no configuration source specified, the wicked client
checks its default sources of configuration defined in
/etc/wicked/client.xml
:
firmware:
iSCSI Boot Firmware Table (iBFT)
compat:
ifcfg
files—implemented for compatibility
Whatever wicked
gets from those sources for a given
interface is applied. The intended order of importance is
firmware
, then compat
—this may
be changed in the future.
For more information, see the wicked
man page.
Nanny is an event and policy driven daemon that is responsible for
asynchronous or unsolicited scenarios such as hotplugging devices. Thus the
nanny daemon helps with starting or restarting delayed or temporarily gone
devices. Nanny monitors device and link changes, and integrates new devices
defined by the current policy set. Nanny continues to set up even if
ifup
already exited because of specified timeout
constraints.
By default, the nanny daemon is active on the system. It is enabled in the
/etc/wicked/common.xml
configuration file:
<config> ... <use-nanny>true</use-nanny> </config>
This setting causes ifup and ifreload to apply a policy with the effective
configuration to the nanny daemon; then, nanny configures
wickedd
and thus ensures
hotplug support. It waits in the background for events or changes (such as
new devices or carrier on).
For bonds and bridges, it may make sense to define the entire device topology in one file (ifcfg-bondX), and bring it up in one go. wicked then can bring up the whole configuration if you specify the top level interface names (of the bridge or bond):
wicked ifup br0
This command automatically sets up the bridge and its dependencies in the appropriate order without the need to list the dependencies (ports, etc.) separately.
To bring up multiple interfaces in one command:
wicked ifup bond0 br0 br1 br2
Or also all interfaces:
wicked ifup all
When you need to use tunnels with Wicked, the TUNNEL_DEVICE
is used for this. It permits to specify an optional device name to bind
the tunnel to the device. The tunneled packets will only be routed via this
device.
For more information, refer to man 5 ifcfg-tunnel
.
With wicked
, there is no need to actually take down an
interface to reconfigure it (unless it is required by the kernel). For
example, to add another IP address or route to a statically configured
network interface, add the IP address to the interface definition, and do
another “ifup” operation. The server will try hard to update
only those settings that have changed. This applies to link-level options
such as the device MTU or the MAC address, and network-level settings, such
as addresses, routes, or even the address configuration mode (for example,
when moving from a static configuration to DHCP).
Things get tricky of course with virtual interfaces combining several real devices such as bridges or bonds. For bonded devices, it is not possible to change certain parameters while the device is up. Doing that will result in an error.
However, what should still work, is the act of adding or removing the child devices of a bond or bridge, or choosing a bond's primary interface.
wicked
is designed to be extensible with shell scripts.
These extensions can be defined in the config.xml
file.
Currently, several classes of extensions are supported:
link configuration: these are scripts responsible for setting up a device's link layer according to the configuration provided by the client, and for tearing it down again.
address configuration: these are scripts responsible for managing a
device's address configuration. Usually address configuration and DHCP
are managed by wicked
itself, but can be implemented
by means of extensions.
firewall extension: these scripts can apply firewall rules.
Typically, extensions have a start and a stop command, an optional “pid file”, and a set of environment variables that get passed to the script.
To illustrate how this is supposed to work, look at a firewall extension
defined in etc/server.xml
:
<dbus-service interface="org.opensuse.Network.Firewall"> <action name="firewallUp" command="/etc/wicked/extensions/firewall up"/> <action name="firewallDown" command="/etc/wicked/extensions/firewall down"/> <!-- default environment for all calls to this extension script --> <putenv name="WICKED_OBJECT_PATH" value="$object-path"/> <putenv name="WICKED_INTERFACE_NAME" value="$property:name"/> <putenv name="WICKED_INTERFACE_INDEX" value="$property:index"/> </dbus-service>
The extension is attached to the
<dbus-service>
tag and defines commands to execute for the actions of this interface.
Further, the declaration can define and initialize environment variables
passed to the actions.
You can extend the handling of configuration files with scripts as well.
For example, DNS updates from leases are ultimately handled by the
extensions/resolver
script, with behavior configured
in server.xml
:
<system-updater name="resolver"> <action name="backup" command="/etc/wicked/extensions/resolver backup"/> <action name="restore" command="/etc/wicked/extensions/resolver restore"/> <action name="install" command="/etc/wicked/extensions/resolver install"/> <action name="remove" command="/etc/wicked/extensions/resolver remove"/> </system-updater>
When an update arrives in wickedd
, the system
updater routines parse the lease and call the appropriate commands
(backup
, install
, etc.) in the
resolver script. This in turn configures the DNS settings using
/sbin/netconfig
, or by manually writing
/run/netconfig/resolv.conf
as a fallback.
This section provides an overview of the network configuration files and explains their purpose and the format used.
/etc/wicked/common.xml
#Edit source
The /etc/wicked/common.xml
file contains common
definitions that should be used by all applications. It is sourced/included
by the other configuration files in this directory. Although you can use
this file to enable debugging across all
wicked
components, we recommend to use the file
/etc/wicked/local.xml
for this purpose. After applying
maintenance updates you might lose your changes as the
/etc/wicked/common.xml
might be overwritten. The
/etc/wicked/common.xml
file includes the
/etc/wicked/local.xml
in the default installation, thus
you typically do not need to modify the
/etc/wicked/common.xml
.
In case you want to disable nanny
by setting the
<use-nanny>
to false
, restart
the wickedd.service
and then run the following command to
apply all configurations and policies:
tux >
sudo
wicked ifup all
The wickedd
, wicked
, or
nanny
programs try to read
/etc/wicked/common.xml
if their own configuration
files do not exist.
/etc/wicked/server.xml
#Edit source
The file /etc/wicked/server.xml
is read by the
wickedd
server process at start-up. The file stores
extensions to the /etc/wicked/common.xml
. On top of
that this file configures handling of a resolver and receiving information
from addrconf
supplicants, for example DHCP.
We recommend to add changes required to this file into a separate file
/etc/wicked/server-local.xml
, that gets included by
/etc/wicked/server.xml
. By using a separate file
you avoid overwriting of your changes during maintenance updates.
/etc/wicked/client.xml
#Edit source
The /etc/wicked/client.xml
is used by the
wicked
command. The file specifies the location of a
script used when discovering devices managed by ibft and configures
locations of network interface configurations.
We recommend to add changes required to this file into a separate file
/etc/wicked/client-local.xml
, that gets included by
/etc/wicked/server.xml
. By using a separate file
you avoid overwriting of your changes during maintenance updates.
/etc/wicked/nanny.xml
#Edit source
The /etc/wicked/nanny.xml
configures types of link
layers. We recommend to add specific configuration into a separate file:
/etc/wicked/nanny-local.xml
to avoid losing the changes
during maintenance updates.
/etc/sysconfig/network/ifcfg-*
#Edit sourceThese files contain the traditional configurations for network interfaces. In SUSE Linux Enterprise 11, this was the only supported format besides iBFT firmware.
wicked
and the ifcfg-*
Files
wicked
reads these files if you specify the
compat:
prefix. According to the SUSE Linux Enterprise Desktop default
configuration in /etc/wicked/client.xml
,
wicked
tries these files before the XML configuration
files in /etc/wicked/ifconfig
.
The --ifconfig
switch is provided mostly for testing only.
If specified, default configuration sources defined in
/etc/wicked/ifconfig
are not applied.
The ifcfg-*
files include information such as the start
mode and the IP address. Possible parameters are described in the manual
page of ifup
. Additionally, most variables from the
dhcp
and wireless
files can be
used in the ifcfg-*
files if a general setting should
be used for only one interface. However, most of the
/etc/sysconfig/network/config
variables are global and
cannot be overridden in ifcfg-files. For example,
NETCONFIG_*
variables are global.
For configuring macvlan
and
macvtab
interfaces, see the
ifcfg-macvlan
and
ifcfg-macvtap
man pages. For example, for a macvlan
interface provide a ifcfg-macvlan0
with settings as
follows:
STARTMODE='auto' MACVLAN_DEVICE='eth0' #MACVLAN_MODE='vepa' #LLADDR=02:03:04:05:06:aa
For ifcfg.template
, see
Section 19.6.2.6, “/etc/sysconfig/network/config
, /etc/sysconfig/network/dhcp
, and /etc/sysconfig/network/wireless
”.
/etc/sysconfig/network/config
, /etc/sysconfig/network/dhcp
, and /etc/sysconfig/network/wireless
#Edit source
The file config
contains general settings for the
behavior of ifup
, ifdown
and
ifstatus
. dhcp
contains settings for
DHCP and wireless
for wireless LAN cards. The variables
in all three configuration files are commented. Some variables from
/etc/sysconfig/network/config
can also be used in
ifcfg-*
files, where they are given a higher priority.
The /etc/sysconfig/network/ifcfg.template
file lists
variables that can be specified in a per interface scope. However, most of
the /etc/sysconfig/network/config
variables are global
and cannot be overridden in ifcfg-files. For example,
NETWORKMANAGER
or
NETCONFIG_*
variables are global.
In SUSE Linux Enterprise 11, DHCPv6 used to work even on networks where IPv6 Router Advertisements (RAs) were not configured properly. Starting with SUSE Linux Enterprise 12, DHCPv6 will correctly require that at least one of the routers on the network sends out RAs that indicate that this network is managed by DHCPv6.
For networks where the router cannot be configured correctly, the ifcfg
option allows the user to override this
behavior by specifying DHCLIENT6_MODE='managed'
in the
ifcfg
file.
You can also activate this workaround with a boot parameter in the
installation system:
ifcfg=eth0=dhcp6,DHCLIENT6_MODE=managed
/etc/sysconfig/network/routes
and /etc/sysconfig/network/ifroute-*
#Edit source
The static routing of TCP/IP packets is determined by the
/etc/sysconfig/network/routes
and
/etc/sysconfig/network/ifroute-*
files. All the static
routes required by the various system tasks can be specified in
/etc/sysconfig/network/routes
: routes to a host, routes
to a host via a gateway and routes to a network. For each interface that
needs individual routing, define an additional configuration file:
/etc/sysconfig/network/ifroute-*
. Replace the wild card
(*
) with the name of the interface. The entries in the
routing configuration files look like this:
# Destination Gateway Netmask Interface Options
The route's destination is in the first column. This column may contain the
IP address of a network or host or, in the case of
reachable name servers, the fully qualified network or
host name. The network should be written in CIDR notation (address with the
associated routing prefix-length) such as 10.10.0.0/16 for IPv4 or fc00::/7
for IPv6 routes. The keyword default
indicates that the
route is the default gateway in the same address family as the gateway. For
devices without a gateway use explicit 0.0.0.0/0 or ::/0 destinations.
The second column contains the default gateway or a gateway through which a host or network can be accessed.
The third column is deprecated; it used to contain the IPv4 netmask of the
destination. For IPv6 routes, the default route, or when using a
prefix-length (CIDR notation) in the first column, enter a dash
(-
) here.
The fourth column contains the name of the interface. If you leave it empty
using a dash (-
), it can cause unintended behavior in
/etc/sysconfig/network/routes
. For more information,
see the routes
man page.
An (optional) fifth column can be used to specify special options. For
details, see the routes
man page.
# --- IPv4 routes in CIDR prefix notation: # Destination [Gateway] - Interface 127.0.0.0/8 - - lo 204.127.235.0/24 - - eth0 default 204.127.235.41 - eth0 207.68.156.51/32 207.68.145.45 - eth1 192.168.0.0/16 207.68.156.51 - eth1 # --- IPv4 routes in deprecated netmask notation" # Destination [Dummy/Gateway] Netmask Interface # 127.0.0.0 0.0.0.0 255.255.255.0 lo 204.127.235.0 0.0.0.0 255.255.255.0 eth0 default 204.127.235.41 0.0.0.0 eth0 207.68.156.51 207.68.145.45 255.255.255.255 eth1 192.168.0.0 207.68.156.51 255.255.0.0 eth1 # --- IPv6 routes are always using CIDR notation: # Destination [Gateway] - Interface 2001:DB8:100::/64 - - eth0 2001:DB8:100::/32 fe80::216:3eff:fe6d:c042 - eth0
/var/run/netconfig/resolv.conf
#Edit source
The domain to which the host belongs is specified in
/var/run/netconfig/resolv.conf
(keyword
search
). Up to six domains with a total of 256
characters can be specified with the search
option.
When resolving a name that is not fully qualified, an attempt is made to
generate one by attaching the individual search
entries. Up to three name servers can be specified with the
nameserver
option, each on a line of its own.
Comments are preceded by hash mark or semicolon signs (#
or ;
). As an example, see
Example 19.6, “/var/run/netconfig/resolv.conf
”.
However, /etc/resolv.conf
should not be edited by
hand. It is generated by the netconfig
script and is a
symbolic link to /run/netconfig/resolv.conf
.
To define static DNS configuration without using YaST, edit the
appropriate variables manually in the
/etc/sysconfig/network/config
file:
NETCONFIG_DNS_STATIC_SEARCHLIST
list of DNS domain names used for host name lookup
NETCONFIG_DNS_STATIC_SERVERS
list of name server IP addresses to use for host name lookup
NETCONFIG_DNS_FORWARDER
the name of the DNS forwarder that needs to be configured, for example
bind
or resolver
NETCONFIG_DNS_RESOLVER_OPTIONS
arbitrary options that will be written to
/var/run/netconfig/resolv.conf
, for example:
debug attempts:1 timeout:10
For more information, see the resolv.conf
man page.
NETCONFIG_DNS_RESOLVER_SORTLIST
list of up to 10 items, for example:
130.155.160.0/255.255.240.0 130.155.0.0
For more information, see the resolv.conf
man
page.
To disable DNS configuration using netconfig, set
NETCONFIG_DNS_POLICY=''
. For more information about
netconfig
, see the netconfig(8)
man page (man 8 netconfig
).
/var/run/netconfig/resolv.conf
## Our domain search example.com # # We use dns.example.com (192.168.1.116) as nameserver nameserver 192.168.1.116
/sbin/netconfig
#Edit source
netconfig
is a modular tool to manage additional network
configuration settings. It merges statically defined settings with settings
provided by autoconfiguration mechanisms as DHCP or PPP according to a
predefined policy. The required changes are applied to the system by calling
the netconfig modules that are responsible for modifying a configuration
file and restarting a service or a similar action.
netconfig
recognizes three main actions. The
netconfig modify
and netconfig remove
commands are used by daemons such as DHCP or PPP to provide or remove
settings to netconfig. Only the netconfig update
command
is available for the user:
modify
The netconfig modify
command modifies the current
interface and service specific dynamic settings and updates the network
configuration. Netconfig reads settings from standard input or from a
file specified with the --lease-file
FILENAME
option and internally stores
them until a system reboot (or the next modify or remove action). Already
existing settings for the same interface and service combination are
overwritten. The interface is specified by the -i
INTERFACE_NAME
parameter. The service
is specified by the -s
SERVICE_NAME
parameter.
remove
The netconfig remove
command removes the dynamic
settings provided by a modificatory action for the specified interface
and service combination and updates the network configuration. The
interface is specified by the -i
INTERFACE_NAME
parameter. The service
is specified by the -s
SERVICE_NAME
parameter.
update
The netconfig update
command updates the network
configuration using current settings. This is useful when the policy or
the static configuration has changed. Use the -m
MODULE_TYPE
parameter to
update a specified service only (dns
,
nis
, or ntp
).
The netconfig policy and the static configuration settings are defined
either manually or using YaST in the
/etc/sysconfig/network/config
file. The dynamic
configuration settings provided by autoconfiguration tools such as DHCP or
PPP are delivered directly by these tools with the netconfig
modify
and netconfig remove
actions.
When NetworkManager is enabled, netconfig (in policy mode auto
)
uses only NetworkManager settings, ignoring settings from any other interfaces
configured using the traditional ifup method. If NetworkManager does not provide any
setting, static settings are used as a fallback. A mixed usage of NetworkManager and
the wicked
method is not supported.
For more information about netconfig
, see man 8
netconfig
.
/etc/hosts
#Edit source
In this file, shown in Example 19.7, “/etc/hosts
”, IP addresses
are assigned to host names. If no name server is implemented, all hosts to
which an IP connection will be set up must be listed here. For each host,
enter a line consisting of the IP address, the fully qualified host name,
and the host name into the file. The IP address must be at the beginning of
the line and the entries separated by blanks and tabs. Comments are always
preceded by the #
sign.
/etc/hosts
#127.0.0.1 localhost 192.168.2.100 jupiter.example.com jupiter 192.168.2.101 venus.example.com venus
/etc/networks
#Edit source
Here, network names are converted to network addresses. The format is
similar to that of the hosts
file, except the network
names precede the addresses. See Example 19.8, “/etc/networks
”.
/etc/networks
#loopback 127.0.0.0 localnet 192.168.0.0
/etc/host.conf
#Edit source
Name resolution—the translation of host and network names via the
resolver library—is controlled by this file. This
file is only used for programs linked to libc4 or libc5. For current glibc
programs, refer to the settings in /etc/nsswitch.conf
.
Each parameter must always be entered on a separate line. Comments are
preceded by a #
sign.
Table 19.2, “Parameters for /etc/host.conf” shows the parameters available. A
sample /etc/host.conf
is shown in
Example 19.9, “/etc/host.conf
”.
order hosts, bind |
Specifies in which order the services are accessed for the name resolution. Available arguments are (separated by blank spaces or commas): |
hosts: searches the
| |
bind: accesses a name server | |
nis: uses NIS | |
multi on/off |
Defines if a host entered in |
nospoof on spoofalert on/off |
These parameters influence the name server spoofing but do not exert any influence on the network configuration. |
trim domainname |
The specified domain name is separated from the host name after host
name resolution (as long as the host name includes the domain name).
This option is useful only if names from the local domain are in the
|
/etc/host.conf
## We have named running order hosts bind # Allow multiple address multi on
/etc/nsswitch.conf
#Edit source
The introduction of the GNU C Library 2.0 was accompanied by the
introduction of the Name Service Switch (NSS). Refer to
the nsswitch.conf(5)
man page and The GNU
C Library Reference Manual for details.
The order for queries is defined in the file
/etc/nsswitch.conf
. A sample
nsswitch.conf
is shown in
Example 19.10, “/etc/nsswitch.conf
”. Comments are preceded by
#
signs. In this example, the entry under the
hosts
database means that a request is sent to
/etc/hosts
(files
) via
DNS.
/etc/nsswitch.conf
#passwd: compat group: compat hosts: files dns networks: files dns services: db files protocols: db files rpc: files ethers: files netmasks: files netgroup: files nis publickey: files bootparams: files automount: files nis aliases: files nis shadow: compat
The “databases” available over NSS are listed in Table 19.3, “Databases Available via /etc/nsswitch.conf”. The configuration options for NSS databases are listed in Table 19.4, “Configuration Options for NSS “Databases””.
|
Mail aliases implemented by |
|
Ethernet addresses. |
|
List of networks and their subnet masks. Only needed, if you use subnetting. |
|
User groups used by |
|
Host names and IP addresses, used by |
|
Valid host and user lists in the network for controlling access
permissions; see the |
|
Network names and addresses, used by |
|
Public and secret keys for Secure_RPC used by NFS and NIS+. |
|
User passwords, used by |
|
Network protocols, used by |
|
Remote procedure call names and addresses, used by
|
|
Network services, used by |
|
Shadow passwords of users, used by |
|
directly access files, for example, |
|
access via a database |
|
NIS, see also Book “Security and Hardening Guide”, Chapter 4 “Using NIS” |
|
can only be used as an extension for |
|
can only be used as an extension for |
/etc/nscd.conf
#Edit source
This file is used to configure nscd (name service cache daemon). See the
nscd(8)
and nscd.conf(5)
man pages. By default, the system entries of passwd
,
groups
and hosts
are cached by nscd. This is important for the
performance of directory services, like NIS and LDAP, because otherwise the
network connection needs to be used for every access to names, groups or
hosts.
If the caching for passwd
is activated, it usually takes
about fifteen seconds until a newly added local user is recognized. Reduce
this waiting time by restarting nscd with:
tux >
sudo
systemctl restart nscd
/etc/HOSTNAME
#Edit source
/etc/HOSTNAME
contains the fully qualified host name
(FQHN). The fully qualified host name is the host name with the domain name
attached. This file must contain only one line (in which the host name is
set). It is read while the machine is booting.
Before you write your configuration to the configuration files, you can test
it. To set up a test configuration, use the ip
command.
To test the connection, use the ping
command.
The command ip
changes the network configuration directly
without saving it in the configuration file. Unless you enter your
configuration in the correct configuration files, the changed network
configuration is lost on reboot.
ifconfig
and route
Are Obsolete
The ifconfig
and route
tools are
obsolete. Use ip
instead. ifconfig
,
for example, limits interface names to 9 characters.
ip
#Edit source
ip
is a tool to show and configure network devices,
routing, policy routing, and tunnels.
ip
is a very complex tool. Its common syntax is
ip
OPTIONS
OBJECT
COMMAND
. You can work with the
following objects:
This object represents a network device.
This object represents the IP address of device.
This object represents an ARP or NDISC cache entry.
This object represents the routing table entry.
This object represents a rule in the routing policy database.
This object represents a multicast address.
This object represents a multicast routing cache entry.
This object represents a tunnel over IP.
If no command is given, the default command is used (usually
list
).
Change the state of a device with the command:
tux >
sudo
ip link set DEV_NAME
For example, to deactivate device eth0, enter
tux >
sudo
ip link set eth0 down
To activate it again, use
tux >
sudo
ip link set eth0 up
If you deactivate a device with
tux >
sudo
ip link set DEV_NAME down
it disables the network interface on a software level.
If you want to simulate losing the link as if the ethernet cable is unplugged or the connected switch is turned off, run
tux >
sudo
ip link set DEV_NAME carrier off
For example, while ip link set
DEV_NAME down
drops all routes using
DEV_NAME, ip link set DEV carrier
off
does not. Be aware that carrier off
requires support from the network device driver.
To connect the device back to the physical network, run
tux >
sudo
ip link set DEV_NAME carrier on
After activating a device, you can configure it. To set the IP address, use
tux >
sudo
ip addr add IP_ADDRESS + dev DEV_NAME
For example, to set the address of the interface eth0 to 192.168.12.154/30
with standard broadcast (option brd
), enter
tux >
sudo
ip addr add 192.168.12.154/30 brd + dev eth0
To have a working connection, you must also configure the default gateway. To set a gateway for your system, enter
tux >
sudo
ip route add default via gateway_ip_address
To display all devices, use
tux >
sudo
ip link ls
To display the running interfaces only, use
tux >
sudo
ip link ls up
To print interface statistics for a device, enter
tux >
sudo
ip -s link ls DEV_NAME
To view additional useful information, specifically about virtual network devices, enter
tux >
sudo
ip -d link ls DEV_NAME
Moreover, to view network layer (IPv4, IPv6) addresses of your devices, enter
tux >
sudo
ip addr
In the output, you can find information about MAC addresses of your devices. To show all routes, use
tux >
sudo
ip route show
For more information about using ip
, enter
ip
help
or see the
man 8 ip
manual page. The help
option
is also available for all ip
subcommands, such as:
tux >
sudo
ip addr help
Find the ip
manual in
/usr/share/doc/packages/iproute2/ip-cref.pdf
.
The ping
command is the standard tool for testing
whether a TCP/IP connection works. It uses the ICMP protocol to send a
small data packet, ECHO_REQUEST datagram, to the destination host,
requesting an immediate reply. If this works, ping
displays a message to that effect. This indicates that the network link is
functioning.
ping
does more than only test the function of the
connection between two computers: it also provides some basic information
about the quality of the connection. In
Example 19.11, “Output of the Command ping”, you can see an example of the
ping
output. The second-to-last line contains
information about the number of transmitted packets, packet loss, and total
time of ping
running.
As the destination, you can use a host name or IP address, for example,
ping
example.com
or
ping
192.168.3.100
. The program sends
packets until you press
Ctrl–C.
If you only need to check the functionality of the connection, you can
limit the number of the packets with the -c
option. For
example to limit ping to three packets, enter
ping
-c 3 example.com
.
ping -c 3 example.com PING example.com (192.168.3.100) 56(84) bytes of data. 64 bytes from example.com (192.168.3.100): icmp_seq=1 ttl=49 time=188 ms 64 bytes from example.com (192.168.3.100): icmp_seq=2 ttl=49 time=184 ms 64 bytes from example.com (192.168.3.100): icmp_seq=3 ttl=49 time=183 ms --- example.com ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2007ms rtt min/avg/max/mdev = 183.417/185.447/188.259/2.052 ms
The default interval between two packets is one second. To change the
interval, ping provides the option -i
. For example, to
increase the ping interval to ten seconds, enter
ping
-i 10 example.com
.
In a system with multiple network devices, it is sometimes useful to send
the ping through a specific interface address. To do so, use the
-I
option with the name of the selected device, for
example, ping
-I wlan1
example.com
.
For more options and information about using ping, enter
ping
-h
or see the
ping (8)
man page.
For IPv6 addresses use the ping6
command. Note, to ping
link-local addresses, you must specify the interface with
-I
. The following command works, if the address is
reachable via eth1
:
ping6 -I eth1 fe80::117:21ff:feda:a425
Apart from the configuration files described above, there are also systemd
unit files and various scripts that load the network services while the
machine is booting. These are started when the system is switched to the
multi-user.target
target. Some of these unit files
and scripts are described in Some Unit Files and Start-Up Scripts for Network Programs. For
more information about systemd
, see
Chapter 15, The systemd
Daemon and for more information about the
systemd
targets, see the man page of
systemd.special
(man
systemd.special
).
network.target
network.target
is the systemd target for
networking, but its mean depends on the settings provided by the system
administrator.
For more information, see http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget/.
multi-user.target
multi-user.target
is the systemd target for a
multiuser system with all required network services.
rpcbind
Starts the rpcbind utility that converts RPC program numbers to universal addresses. It is needed for RPC services, such as an NFS server.
ypserv
Starts the NIS server.
ypbind
Starts the NIS client.
/etc/init.d/nfsserver
Starts the NFS server.
/etc/init.d/postfix
Controls the postfix process.
For some systems, there is a desire to implement network connections that comply to more than the standard data security or availability requirements of a typical Ethernet device. In these cases, several Ethernet devices can be aggregated to a single bonding device.
The configuration of the bonding device is done by means of bonding module
options. The behavior is mainly affected by the mode of the bonding device.
By default, this is active-backup
which means
that a different slave device will become active if the active slave fails.
The following bonding modes are available:
Packets are transmitted in round-robin fashion from the first to the last available interface. Provides fault tolerance and load balancing.
Only one network interface is active. If it fails, a different interface becomes active. This setting is the default for SUSE Linux Enterprise Desktop. Provides fault tolerance.
Traffic is split between all available interfaces based on the following
policy: [(source MAC address XOR'd with destination MAC address
XOR packet type ID) modulo slave count]
Requires support from
the switch. Provides fault tolerance and load balancing.
All traffic is broadcast on all interfaces. Requires support from the switch. Provides fault tolerance.
Aggregates interfaces into groups that share the same speed and duplex
settings. Requires ethtool
support in the interface
drivers, and a switch that supports and is configured for IEEE 802.3ad
Dynamic link aggregation. Provides fault tolerance and load balancing.
Adaptive transmit load balancing. Requires ethtool
support in the interface drivers but not switch support. Provides fault
tolerance and load balancing.
Adaptive load balancing. Requires ethtool
support in
the interface drivers but not switch support. Provides fault tolerance and
load balancing.
For a more detailed description of the modes, see https://www.kernel.org/doc/Documentation/networking/bonding.txt.
Using bonding devices is only of interest for machines where you have multiple real network cards available. In most configurations, this means that you should use the bonding configuration only in Dom0. Only if you have multiple network cards assigned to a VM Guest system it may also be useful to set up the bond in a VM Guest.
There is a conflict with the tlb/alb bonding configuration and Power firmware. In short, the bonding driver in tlb/alb mode sends Ethernet Loopback packets with both the source and destination MAC addresses listed as the Virtual Ethernet MAC address. These packets are not supported by Power firmware. Therefore bonding modes 5 and 6 are unsupported by ibmveth.
To configure a bonding device, use the following procedure:
Run
› › .Use
and change the to . Proceed with .Select how to assign the IP address to the bonding device. Three methods are at your disposal:
No IP Address
Dynamic Address (with DHCP or Zeroconf)
Statically assigned IP Address
Use the method that is appropriate for your environment.
In the
tab, select the Ethernet devices that should be included into the bond by activating the related check box.Edit the
and choose a bonding mode.
Make sure that the parameter miimon=100
is added to the
. Without this parameter, the data
integrity is not checked regularly.
Click
and leave YaST with to create the device.In specific network environments (such as High Availability), there are cases when you need to replace a bonding slave interface with another one. The reason may be a constantly failing network device. The solution is to set up hotplugging of bonding slaves.
The bond is configured as usual (according to man 5
ifcfg-bonding
), for example:
ifcfg-bond0 STARTMODE='auto' # or 'onboot' BOOTPROTO='static' IPADDR='192.168.0.1/24' BONDING_MASTER='yes' BONDING_SLAVE_0='eth0' BONDING_SLAVE_1='eth1' BONDING_MODULE_OPTS='mode=active-backup miimon=100'
The slaves are specified with STARTMODE=hotplug
and
BOOTPROTO=none
:
ifcfg-eth0 STARTMODE='hotplug' BOOTPROTO='none' ifcfg-eth1 STARTMODE='hotplug' BOOTPROTO='none'
BOOTPROTO=none
uses the ethtool
options (when provided), but does not set the link up on ifup
eth0
. The reason is that the slave interface is controlled by the
bond master.
STARTMODE=hotplug
causes the slave interface to join the
bond automatically when it is available.
The udev
rules in
/etc/udev/rules.d/70-persistent-net.rules
need to be
changed to match the device by bus ID (udev KERNELS
keyword equal to "SysFS BusID" as visible in hwinfo
--netcard
) instead of by MAC address. This allows replacement of
defective hardware (a network card in the same slot but with a different
MAC) and prevents confusion when the bond changes the MAC address of all its
slaves.
For example:
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", KERNELS=="0000:00:19.0", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"
At boot time, the systemd network.service
does not
wait for the hotplug slaves, but for the bond to become ready, which
requires at least one available slave. When one of the slave interfaces gets
removed (unbind from NIC driver, rmmod
of the NIC driver
or true PCI hotplug remove) from the system, the kernel removes it from the
bond automatically. When a new card is added to the system (replacement of
the hardware in the slot), udev
renames it using
the bus-based persistent name rule to the name of the slave, and calls
ifup
for it. The ifup
call
automatically joins it into the bond.
The term “link aggregation” is the general term which describes combining (or aggregating) a network connection to provide a logical layer. Sometimes you find the terms “channel teaming”, “Ethernet bonding”, “port truncating”, etc. which are synonyms and refer to the same concept.
This concept is widely known as “bonding” and was originally integrated into the Linux kernel (see Section 19.7, “Setting Up Bonding Devices” for the original implementation). The term Network Teaming is used to refer to the new implementation of this concept.
The main difference between bonding and Network Teaming is that teaming supplies a set of small kernel modules responsible for providing an interface for teamd instances. Everything else is handled in user space. This is different from the original bonding implementation which contains all of its functionality exclusively in the kernel. For a comparison refer to Table 19.5, “Feature Comparison between Bonding and Team”.
Feature | Bonding | Team |
---|---|---|
broadcast, round-robin TX policy | yes | yes |
active-backup TX policy | yes | yes |
LACP (802.3ad) support | yes | yes |
hash-based TX policy | yes | yes |
user can set hash function | no | yes |
TX load-balancing support (TLB) | yes | yes |
TX load-balancing support for LACP | no | yes |
Ethtool link monitoring | yes | yes |
ARP link monitoring | yes | yes |
NS/NA (IPV6) link monitoring | no | yes |
RCU locking on TX/RX paths | no | yes |
port prio and stickiness | no | yes |
separate per-port link monitoring setup | no | yes |
multiple link monitoring setup | limited | yes |
VLAN support | yes | yes |
multiple device stacking | yes | yes |
Source: http://libteam.org/files/teamdev.pp.pdf |
Both implementations, bonding and Network Teaming, can be used in parallel. Network Teaming is an alternative to the existing bonding implementation. It does not replace bonding.
Network Teaming can be used for different use cases. The two most important use cases are explained later and involve:
Load balancing between different network devices.
Failover from one network device to another in case one of the devices should fail.
Currently, there is no YaST module to support creating a teaming device. You need to configure Network Teaming manually. The general procedure is shown below which can be applied for all your Network Teaming configurations:
Make sure you have all the necessary packages installed. Install the packages libteam-tools, libteamdctl0, and python-libteam.
Create a configuration file under
/etc/sysconfig/network/
. Usually it will be
ifcfg-team0
. If you need more than one Network Teaming
device, give them ascending numbers.
This configuration file contains several variables which are explained in
the man pages (see man ifcfg
and man
ifcfg-team
). An example configuration can be found in your
system in the file /etc/sysconfig/network/ifcfg.template
.
Remove the configuration files of the interfaces which will be used for the
teaming device (usually ifcfg-eth0
and
ifcfg-eth1
).
It is recommended to make a backup and remove both files. Wicked will re-create the configuration files with the necessary parameters for teaming.
Optionally, check if everything is included in Wicked's configuration file:
tux >
sudo
wicked show-config
Start the Network Teaming device team0
:
tux >
sudo
wicked ifup all team0
In case you need additional debug information, use the option
--debug all
after the all
subcommand.
Check the status of the Network Teaming device. This can be done by the following commands:
Get the state of the teamd instance from Wicked:
tux >
sudo
wicked ifstatus --verbose team0
Get the state of the entire instance:
tux >
sudo
teamdctl team0 state
Get the systemd state of the teamd instance:
tux >
sudo
systemctl status teamd@team0
Each of them shows a slightly different view depending on your needs.
In case you need to change something in the
ifcfg-team0
file afterward, reload its configuration
with:
tux >
sudo
wicked ifreload team0
Do not use systemctl
for starting or
stopping the teaming device! Instead, use the wicked
command as shown above.
To completely remove the team device, use this procedure:
Stop the Network Teaming device team0
:
tux >
sudo
wicked ifdown team0
Rename the file /etc/sysconfig/network/ifcfg-team0
to /etc/sysconfig/network/.ifcfg-team0
.
Inserting a dot in front of the file name makes it
“invisible” for wicked. If you really do not need the
configuration anymore, you can also remove the file.
Reload the configuration:
tux >
sudo
wicked ifreload all
Load balancing is used to improve bandwidth. Use the following configuration
file to create a Network Teaming device with load balancing capabilities. Proceed
with Procedure 19.1, “General Procedure” to set up the device. Check the
output with teamdctl
.
STARTMODE=auto 1 BOOTPROTO=static 2 IPADDRESS="192.168.1.1/24" 2 IPADDR6="fd00:deca:fbad:50::1/64" 2 TEAM_RUNNER="loadbalance" 3 TEAM_LB_TX_HASH="ipv4,ipv6,eth,vlan" TEAM_LB_TX_BALANCER_NAME="basic" TEAM_LB_TX_BALANCER_INTERVAL="100" TEAM_PORT_DEVICE_0="eth0" 4 TEAM_PORT_DEVICE_1="eth1" 4 TEAM_LW_NAME="ethtool" 5 TEAM_LW_ETHTOOL_DELAY_UP="10" 6 TEAM_LW_ETHTOOL_DELAY_DOWN="10" 6
Controls the start of the teaming device. The value of
In case you need to control the device yourself (and prevent it from
starting automatically), set | |
Sets a static IP address (here
If the Network Teaming device should use a dynamic IP address, set
| |
Sets | |
Specifies one or more devices which should be aggregated to create the Network Teaming device. | |
Defines a link watcher to monitor the state of subordinate devices. The
default value
If you need a higher confidence in the connection, use the
| |
Defines the delay in milliseconds between the link coming up (or down) and the runner being notified. |
Failover is used to ensure high availability of a critical Network Teaming device by involving a parallel backup network device. The backup network device is running all the time and takes over if and when the main device fails.
Use the following configuration file to create a Network Teaming device with
failover capabilities. Proceed with Procedure 19.1, “General Procedure” to
set up the device. Check the output with teamdctl
.
STARTMODE=auto 1 BOOTPROTO=static 2 IPADDR="192.168.1.2/24" 2 IPADDR6="fd00:deca:fbad:50::2/64" 2 TEAM_RUNNER=activebackup 3 TEAM_PORT_DEVICE_0="eth0" 4 TEAM_PORT_DEVICE_1="eth1" 4 TEAM_LW_NAME=ethtool 5 TEAM_LW_ETHTOOL_DELAY_UP="10" 6 TEAM_LW_ETHTOOL_DELAY_DOWN="10" 6
Controls the start of the teaming device. The value of
In case you need to control the device yourself (and prevent it from
starting automatically), set | |
Sets a static IP address (here
If the Network Teaming device should use a dynamic IP address, set
| |
Sets | |
Specifies one or more devices which should be aggregated to create the Network Teaming device. | |
Defines a link watcher to monitor the state of subordinate devices. The
default value
If you need a higher confidence in the connection, use the
| |
Defines the delay in milliseconds between the link coming up (or down) and the runner being notified. |
VLAN is an abbreviation of Virtual Local Area Network. It allows the running of multiple logical (virtual) Ethernets over one single physical Ethernet. It logically splits the network into different broadcast domains so that packets are only switched between ports that are designated for the same VLAN.
The following use case creates two static VLANs on top of a team device:
vlan0
,
bound to the IP address 192.168.10.1
vlan1
,
bound to the IP address 192.168.20.1
Proceed as follows:
Enable the VLAN tags on your switch. To use load balancing for your team device, your switch needs to be capable of Link Aggregation Control Protocol (LACP) (802.3ad). Consult your hardware manual about the details.
Decide if you want to use load balancing or failover for your team device. Set up your team device as described in Section 19.8.1, “Use Case: Load Balancing with Network Teaming” or Section 19.8.2, “Use Case: Failover with Network Teaming”.
In /etc/sysconfig/network
create a file
ifcfg-vlan0
with the following content:
STARTMODE="auto" BOOTPROTO="static" 1 IPADDR='192.168.10.1/24' 2 ETHERDEVICE="team0" 3 VLAN_ID="0" 4 VLAN='yes'
Defines a fixed IP address, specified in | |
Defines the IP address, here with its netmask. | |
Contains the real interface to use for the VLAN interface, here our
team device ( | |
Specifies a unique ID for the VLAN. Preferably, the file name and the
|
Copy the file /etc/sysconfig/network/ifcfg-vlan0
to
/etc/sysconfig/network/ifcfg-vlan1
and change the
following values:
IPADDR
from 192.168.10.1/24
to 192.168.20.1/24
.
VLAN_ID
from 0
to
1
.
Start the two VLANs:
root #
wicked
ifup vlan0 vlan1
Check the output of ifconfig
:
root #
ifconfig
-a [...] vlan0 Link encap:Ethernet HWaddr 08:00:27:DC:43:98 inet addr:192.168.10.1 Bcast:192.168.10.255 Mask:255.255.255.0 inet6 addr: fe80::a00:27ff:fedc:4398/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:12 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 b) TX bytes:816 (816.0 b) vlan1 Link encap:Ethernet HWaddr 08:00:27:DC:43:98 inet addr:192.168.20.1 Bcast:192.168.20.255 Mask:255.255.255.0 inet6 addr: fe80::a00:27ff:fedc:4398/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:12 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 b) TX bytes:816 (816.0 b)
SUSE® Linux Enterprise Desktop supports printing with many types of printers, including remote network printers. Printers can be configured manually or with YaST. For configuration instructions, refer to Book “Deployment Guide”, Chapter 15 “Setting Up Hardware Components with YaST”, Section 15.3 “Setting Up a Printer”. Both graphical and command line utilities are available for starting and managing print jobs. If your printer does not work as expected, refer to Section 20.8, “Troubleshooting”.
CUPS (Common Unix Printing System) is the standard print system in SUSE Linux Enterprise Desktop.
Printers can be distinguished by interface, such as USB or network, and printer language. When buying a printer, make sure that the printer has an interface that is supported (USB, Ethernet, or Wi-Fi) and a suitable printer language. Printers can be categorized on the basis of the following three classes of printer languages:
PostScript is the printer language in which most print jobs in Linux and Unix are generated and processed by the internal print system. If PostScript documents can be processed directly by the printer and do not need to be converted in additional stages in the print system, the number of potential error sources is reduced.
Currently PostScript is being replaced by PDF as the standard print job format. PostScript+PDF printers that can directly print PDF (in addition to PostScript) already exist. For traditional PostScript printers PDF needs to be converted to PostScript in the printing workflow.
In the case of known printer languages, the print system can convert PostScript jobs to the respective printer language with Ghostscript. This processing stage is called interpreting. The best-known languages are PCL (which is mostly used by HP printers and their clones) and ESC/P (which is used by Epson printers). These printer languages are usually supported by Linux and produce an adequate print result. Linux may not be able to address some special printer functions. Except for HP and Epson, there are currently no printer manufacturers who develop Linux drivers and make them available to Linux distributors under an open source license.
These printers do not support any of the common printer languages. They use their own undocumented printer languages, which are subject to change when a new edition of a model is released. Usually only Windows drivers are available for these printers. See Section 20.8.1, “Printers without Standard Printer Language Support” for more information.
Before you buy a new printer, refer to the following sources to check how well the printer you intend to buy is supported:
The OpenPrinting home page with the printer database. The database shows the latest Linux support status. However, a Linux distribution can only integrate the drivers available at production time. Accordingly, a printer currently rated as “perfectly supported” may not have had this status when the latest SUSE Linux Enterprise Desktop version was released. Thus, the databases may not necessarily indicate the correct status, but only provide an approximation.
The Ghostscript Web page.
/usr/share/doc/packages/ghostscript/catalog.devices
List of built-in Ghostscript drivers.
The user creates a print job. The print job consists of the data to print plus information for the spooler. This includes the name of the printer or the name of the print queue, and optionally, information for the filter, such as printer-specific options.
At least one dedicated print queue exists for every printer. The spooler holds the print job in the queue until the desired printer is ready to receive data. When the printer is ready, the spooler sends the data through the filter and back-end to the printer.
The filter converts the data generated by the application that is printing (usually PostScript or PDF, but also ASCII, JPEG, etc.) into printer-specific data (PostScript, PCL, ESC/P, etc.). The features of the printer are described in the PPD files. A PPD file contains printer-specific options with the parameters needed to enable them on the printer. The filter system makes sure that options selected by the user are enabled.
If you use a PostScript printer, the filter system converts the data into printer-specific PostScript. This does not require a printer driver. If you use a non-PostScript printer, the filter system converts the data into printer-specific data. This requires a printer driver suitable for your printer. The back-end receives the printer-specific data from the filter then passes it to the printer.
There are various possibilities for connecting a printer to the system. The configuration of CUPS does not distinguish between a local printer and a printer connected to the system over the network. For more information about the printer connection, read the article CUPS in a Nutshell at https://en.opensuse.org/SDB:CUPS_in_a_Nutshell.
When connecting the printer to the machine, do not forget that only USB devices can be plugged in or unplugged during operation. To avoid damaging your system or printer, shut down the system before changing any connections that are not USB.
PPD (PostScript printer description) is the computer language that describes the properties, like resolution, and options, such as the availability of a duplex unit. These descriptions are required for using various printer options in CUPS. Without a PPD file, the print data would be forwarded to the printer in a “raw” state, which is usually not desired.
To configure a PostScript printer, the best approach is to get a suitable
PPD file. Many PPD files are available in the packages
manufacturer-PPDs
and
OpenPrintingPPDs-postscript
. See
Section 20.7.3, “PPD Files in Various Packages” and
Section 20.8.2, “No Suitable PPD File Available for a PostScript Printer”.
New PPD files can be stored in the directory
/usr/share/cups/model/
or added to the print system
with YaST as described in Book “Deployment Guide”, Chapter 15 “Setting Up Hardware Components with YaST”, Section 15.3.1.1 “Adding Drivers with YaST”.
Subsequently, the PPD file can be selected during the printer setup.
Be careful if a printer manufacturer wants you to install entire software packages. This kind of installation may result in the loss of the support provided by SUSE Linux Enterprise Desktop. Also, print commands may work differently and the system may no longer be able to address devices of other manufacturers. For this reason, the installation of manufacturer software is not recommended.
A network printer can support various protocols, some even concurrently. Although most of the supported protocols are standardized, some manufacturers modify the standard. Manufacturers then provide drivers for only a few operating systems. Unfortunately, Linux drivers are rarely provided. The current situation is such that you cannot act on the assumption that every protocol works smoothly in Linux. Therefore, you may need to experiment with various options to achieve a functional configuration.
CUPS supports the socket
,
LPD
, IPP
and
smb
protocols.
Socket refers to a connection in which the plain
print data is sent directly to a TCP socket. Some socket port numbers
that are commonly used are 9100
or 35
.
The device URI (uniform resource identifier) syntax is:
socket://IP.OF.THE.PRINTER:PORT,
for example: socket://192.168.2.202:9100/
.
The LPD protocol is described in RFC 1179. Under this protocol, some
job-related data, such as the ID of the print queue, is sent before the
actual print data is sent. Therefore, a print queue must be specified
when configuring the LPD protocol. The implementations of diverse printer
manufacturers are flexible enough to accept any name as the print queue.
If necessary, the printer manual should indicate what name to use. LPT,
LPT1, LP1 or similar names are often used. The port number for an LPD
service is 515
. An example device URI is
lpd://192.168.2.202/LPT1
.
IPP is based on the HTTP protocol. With
IPP, more job-related data is transmitted than with the other protocols.
CUPS uses IPP for internal data transmission. The name of the print queue
is necessary to configure IPP correctly. The port number for IPP is
631
. Example device URIs are
ipp://192.168.2.202/ps
and
ipp://192.168.2.202/printers/ps
.
CUPS also supports printing on printers connected to Windows shares. The
protocol used for this purpose is SMB. SMB uses the port numbers
137
, 138
and 139
.
Example device URIs are
smb://user:password@workgroup/smb.example.com/printer
,
smb://user:password@smb.example.com/printer
, and
smb://smb.example.com/printer
.
The protocol supported by the printer must be determined before
configuration. If the manufacturer does not provide the needed information,
the command nmap
(which comes with the
nmap
package) can be used to ascertain the
protocol. nmap
checks a host for open ports. For example:
tux >
nmap -p 35,137-139,515,631,9100-10000 IP.OF.THE.PRINTER
CUPS can be configured with command line tools like
lpinfo
, lpadmin
and
lpoptions
. You need a device URI consisting of a
back-end, such as USB, and parameters. To determine valid device URIs on
your system use the command lpinfo -v | grep ":/"
:
tux >
sudo
lpinfo -v | grep ":/" direct usb://ACME/FunPrinter%20XL network socket://192.168.2.253
With lpadmin
the CUPS server administrator can add,
remove or manage print queues. To add a print queue, use the following
syntax:
tux >
sudo
lpadmin -p QUEUE -v DEVICE-URI -P PPD-FILE -E
Then the device (-v
) is available as
QUEUE (-p
), using the specified
PPD file (-P
). This means that you must know the PPD file
and the device URI to configure the printer manually.
Do not use -E
as the first option. For all CUPS commands,
-E
as the first argument sets use of an encrypted
connection. To enable the printer, -E
must be used as shown
in the following example:
tux >
sudo
lpadmin -p ps -v usb://ACME/FunPrinter%20XL -P \ /usr/share/cups/model/Postscript.ppd.gz -E
The following example configures a network printer:
tux >
sudo
lpadmin -p ps -v socket://192.168.2.202:9100/ -P \ /usr/share/cups/model/Postscript-level1.ppd.gz -E
For more options of lpadmin
, see the man page of
lpadmin(8)
.
During printer setup, certain options are set as default. These options can be modified for every print job (depending on the print tool used). Changing these default options with YaST is also possible. Using command line tools, set default options as follows:
First, list all options:
tux >
sudo
lpoptions -p QUEUE -l
Example:
Resolution/Output Resolution: 150dpi *300dpi 600dpi
The activated default option is identified by a preceding asterisk
(*
).
Change the option with lpadmin
:
tux >
sudo
lpadmin -p QUEUE -o Resolution=600dpi
Check the new setting:
tux >
sudo
lpoptions -p QUEUE -l Resolution/Output Resolution: 150dpi 300dpi *600dpi
When a normal user runs lpoptions
, the settings are
written to ~/.cups/lpoptions
. However,
root
settings are written to
/etc/cups/lpoptions
.
To print from the command line, enter lp -d
QUEUENAME FILENAME,
substituting the corresponding names for
QUEUENAME and
FILENAME.
Some applications rely on the lp
command for printing. In
this case, enter the correct command in the application's print dialog,
usually without specifying FILENAME, for example,
lp -d
QUEUENAME.
Several CUPS features have been adapted for SUSE Linux Enterprise Desktop. Some of the most important changes are covered here.
After completing a default installation of SUSE Linux Enterprise Desktop,
firewalld
is active and the network interfaces are configured to be in
the public
zone, which blocks incoming traffic.
When firewalld
is active, you may need to configure it to
allow clients to browse network printers by allowing
mdns
and ipp
through
the internal network zone. The public zone should never
expose printer queues.
(More
information about the firewalld
configuration is available in
Book “Security and Hardening Guide”, Chapter 23 “Masquerading and Firewalls”, Section 23.4 “firewalld
” and at
https://en.opensuse.org/SDB:CUPS_and_SANE_Firewall_settings.)
Normally, a CUPS client runs on a regular workstation located in a trusted
network environment behind a firewall. In this case it is recommended to
configure the network interface to be in the Internal
Zone
, so the workstation is reachable from within the network.
If the CUPS server is part of a trusted network environment protected by a
firewall, the network interface should be configured to be in the
Internal Zone
of the firewall. It is not recommended to
set up a CUPS server in an untrusted network environment unless you ensure
that it is protected by special firewall rules and secure settings in
the CUPS configuration.
CUPS servers regularly announce the availability and status information of shared printers over the network. Clients can access this information to display a list of available printers in printing dialogs, for example. This is called “browsing”.
CUPS servers announce their print queues over the network either via the
traditional CUPS browsing protocol, or via Bonjour/DNS-SD. To enable browsing network print queues, the service
cups-browsed
needs to run on all
clients that print via CUPS servers.
cups-browsed
is not started by
default. To start it for the active session, use sudo systemctl
start cups-browsed
. To ensure it is automatically started after
booting, enable it with sudo systemctl enable
cups-browsed
on all clients.
In case browsing does not work after having started
cups-browsed
, the CUPS server(s)
probably announce the network print queues via Bonjour/DNS-SD. In this case
you need to additionally install the package
avahi
and start the associated
service with sudo systemctl start avahi-daemon
on all
clients.
See Section 20.7.1, “CUPS and Firewall” for information
on allowing printer browsing through firewalld
.
The YaST printer configuration sets up the queues for CUPS using the PPD
files installed in /usr/share/cups/model
. To find the
suitable PPD files for the printer model, YaST compares the vendor and
model determined during hardware detection with the vendors and models in
all PPD files. For this purpose, the YaST printer configuration generates
a database from the vendor and model information extracted from the PPD
files.
The configuration using only PPD files and no other information sources has
the advantage that the PPD files in
/usr/share/cups/model
can be modified freely. For
example, if you have PostScript printers the PPD files can be copied
directly to /usr/share/cups/model
(if they do not
already exist in the manufacturer-PPDs
or
OpenPrintingPPDs-postscript
packages) to achieve
an optimum configuration for your printers.
Additional PPD files are provided by the following packages:
gutenprint
: the Gutenprint driver and its matching PPDs
splix
: the SpliX driver and its matching PPDs
OpenPrintingPPDs-ghostscript
: PPDs for Ghostscript built-in drivers
OpenPrintingPPDs-hpijs
: PPDs for the HPIJS driver for non-HP printers
The following sections cover some of the most frequently encountered printer hardware and software problems and ways to solve or circumvent these problems. Among the topics covered are GDI printers, PPD files and port configuration. Common network printer problems, defective printouts, and queue handling are also addressed.
These printers do not support any common printer language and can only be addressed with special proprietary control sequences. Therefore they can only work with the operating system versions for which the manufacturer delivers a driver. GDI is a programming interface developed by Microsoft* for graphics devices. Usually the manufacturer delivers drivers only for Windows, and since the Windows driver uses the GDI interface these printers are also called GDI printers. The actual problem is not the programming interface, but that these printers can only be addressed with the proprietary printer language of the respective printer model.
Some GDI printers can be switched to operate either in GDI mode or in one of the standard printer languages. See the manual of the printer whether this is possible. Some models require special Windows software to do the switch (note that the Windows printer driver may always switch the printer back into GDI mode when printing from Windows). For other GDI printers there are extension modules for a standard printer language available.
Some manufacturers provide proprietary drivers for their printers. The disadvantage of proprietary printer drivers is that there is no guarantee that these work with the installed print system or that they are suitable for the various hardware platforms. In contrast, printers that support a standard printer language do not depend on a special print system version or a special hardware platform.
Instead of spending time trying to make a proprietary Linux driver work, it may be more cost-effective to purchase a printer which supports a standard printer language (preferably PostScript). This would solve the driver problem once and for all, eliminating the need to install and configure special driver software and obtain driver updates that may be required because of new developments in the print system.
If the manufacturer-PPDs
or
OpenPrintingPPDs-postscript
packages do not
contain a suitable PPD file for a PostScript printer, it should be possible
to use the PPD file from the driver CD of the printer manufacturer or
download a suitable PPD file from the Web page of the printer manufacturer.
If the PPD file is provided as a zip archive (.zip) or a self-extracting
zip archive (.exe
), unpack it with
unzip
. First, review the license terms of the PPD file.
Then use the cupstestppd
utility to check if the PPD
file complies with “Adobe PostScript Printer Description File Format
Specification, version 4.3.” If the utility returns
“FAIL,” the errors in the PPD files are serious and are likely
to cause major problems. The problem spots reported by
cupstestppd
should be eliminated. If necessary, ask the
printer manufacturer for a suitable PPD file.
Connect the printer directly to the computer. For test purposes, configure the printer as a local printer. If this works, the problems are related to the network.
The TCP/IP network and name resolution must be functional.
lpd
Use the following command to test if a TCP connection can be established
to lpd
(port 515
) on
HOST:
tux >
netcat -z HOST 515 && echo ok || echo failed
If the connection to lpd
cannot be established,
lpd
may not be active or there may be basic network
problems.
Provided that the respective
lpd
is active and the host accepts queries, run the following command as root
to query a status report for
QUEUE on remote
HOST:
root #
echo -e "\004queue" \
| netcat -w 2 -p 722 HOST 515
If lpd
does not respond, it may not be active or
there may be basic network problems. If lpd
responds,
the response should show why printing is not possible on the
queue
on host
. If you receive a
response like that shown in Example 20.1, “Error Message from lpd
”, the problem is
caused by the remote lpd
.
lpd
#lpd: your host does not have line printer access lpd: queue does not exist printer: spooling disabled printer: printing disabled
cupsd
A CUPS network server can broadcast its queues by default every 30
seconds on UDP port 631
. Accordingly, the following
command can be used to test whether there is a broadcasting CUPS network
server in the network. Make sure to stop your local CUPS daemon before
executing the command.
tux >
netcat -u -l -p 631 & PID=$! ; sleep 40 ; kill $PID
If a broadcasting CUPS network server exists, the output appears as shown in Example 20.2, “Broadcast from the CUPS Network Server”.
ipp://192.168.2.202:631/printers/queue
The following command can be used to test if a TCP connection can be
established to cupsd
(port 631
) on
HOST:
tux >
netcat -z HOST 631 && echo ok || echo failed
If the connection to cupsd
cannot be established,
cupsd
may not be active or there may be basic network
problems. lpstat -h
HOST
-l -t returns a (possibly very long) status report for all queues on
HOST, provided the respective
cupsd
is active and the host accepts queries.
The next command can be used to test if the QUEUE on HOST accepts a print job consisting of a single carriage-return character. Nothing should be printed. Possibly, a blank page may be ejected.
tux >
echo -en "\r" \
| lp -d queue -h HOST
Spoolers running in a print server machine sometimes cause problems when they need to deal with multiple print jobs. Since this is caused by the spooler in the print server machine, there no way to resolve this issue. As a work-around, circumvent the spooler in the print server machine by addressing the printer connected to the print server machine directly with the TCP socket. See Section 20.4, “Network Printers”.
In this way, the print server machine is reduced to a converter between the
various forms of data transfer (TCP/IP network and local printer
connection). To use this method, you need to know the TCP port on the
print server machine. If the printer is connected to the print server machine
and turned on, this TCP port can usually be determined with the
nmap
utility from the nmap
package some time after the print server machine is powered up. For example,
nmap
IP-address may
deliver the following output for a print server machine:
Port State Service 23/tcp open telnet 80/tcp open http 515/tcp open printer 631/tcp open cups 9100/tcp open jetdirect
This output indicates that the printer connected to the print server machine
can be addressed via TCP socket on port 9100
. By
default, nmap
only checks several commonly known
ports listed in /usr/share/nmap/nmap-services
. To
check all possible ports, use the command nmap
-p
FROM_PORT-TO_PORT IP_ADDRESS.
This may take some time. For further information, refer to the man page
of nmap
.
Enter a command like
tux >
echo -en "\rHello\r\f" | netcat -w 1 IP-address port
cat file | netcat -w 1 IP-address port
to send character strings or files directly to the respective port to test if the printer can be addressed on this port.
For the print system, the print job is completed when the CUPS back-end completes the data transfer to the recipient (printer). If further processing on the recipient fails (for example, if the printer is not able to print the printer-specific data) the print system does not notice this. If the printer cannot print the printer-specific data, select a PPD file that is more suitable for the printer.
If the data transfer to the recipient fails entirely after several
attempts, the CUPS back-end, such as USB
or
socket
, reports an error to the print system (to
cupsd
). The back-end determines how many unsuccessful
attempts are appropriate until the data transfer is reported as impossible.
As further attempts would be in vain, cupsd
disables
printing for the respective queue. After eliminating the cause of the
problem, the system administrator must re-enable printing with the command
cupsenable
.
If a CUPS network server broadcasts its queues to the client hosts via
browsing and a suitable local cupsd
is active on the
client hosts, the client cupsd
accepts print jobs from
applications and forwards them to the cupsd
on the
server. When cupsd
on the server accepts a print job, it
is assigned a new job number. Therefore, the job number on the client host
is different from the job number on the server. As a print job is usually
forwarded immediately, it cannot be deleted with the job number on the
client host This is because the client cupsd
regards the
print job as completed when it has been forwarded to the server
cupsd
.
To delete the print job on the server, use a
command such as lpstat -h cups.example.com -o
to determine the
job number on the server. This assumes that the server has not already
completed the print job (that is, sent it completely to the printer). Use
the obtained job
number to delete the print job on the server as follows:
tux >
cancel -h cups.example.com QUEUE-JOBNUMBER
If you switch the printer off or shut down the computer during the printing
process, print jobs remain in the queue. Printing resumes when the computer
(or the printer) is switched back on. Defective print jobs must be removed
from the queue with cancel
.
If a print job is corrupted or an error occurs in the communication between the host and the printer, the printer cannot process the data correctly and prints numerous sheets of paper with unintelligible characters. To fix the problem, follow these steps:
To stop printing, remove all paper from ink jet printers or open the paper trays of laser printers. High-quality printers have a button for canceling the current printout.
The print job may still be in the queue, because jobs are only removed
after they are sent completely to the printer. Use lpstat
-o
or lpstat -h cups.example.com -o
to check which
queue is currently printing. Delete the print job with
cancel
QUEUE-JOBNUMBER or
cancel -h cups.example.com
QUEUE-JOBNUMBER.
Some data may still be transferred to the printer even though the print job has been deleted from the queue. Check if a CUPS back-end process is still running for the respective queue and terminate it.
Reset the printer completely by switching it off for some time. Then insert the paper and turn on the printer.
Use the following generic procedure to locate problems in CUPS:
Set LogLevel debug
in
/etc/cups/cupsd.conf
.
Stop cupsd
.
Remove /var/log/cups/error_log*
to avoid having to
search through very large log files.
Start cupsd
.
Repeat the action that led to the problem.
Check the messages in /var/log/cups/error_log*
to
identify the cause of the problem.
In-depth information about printing on SUSE Linux Enterprise Desktop is presented in the
openSUSE Support Database at https://en.opensuse.org/Portal:Printing. Solutions to many specific problems are presented in the
SUSE Knowledgebase (https://www.suse.com/support/). Locate the relevant articles
with a text search for CUPS
.
SUSE Linux Enterprise Desktop includes the X.org server, Wayland and the GNOME desktop. This chapter describes the configuration of the graphical user interface for all users.
The X.org server is the de facto standard for implementing the X11 protocol. X is network-based, enabling applications started on one host to be displayed on another host connected over any kind of network (LAN or Internet).
Usually, the X Window System needs no configuration. The hardware is
dynamically detected during X start-up. The use of
xorg.conf
is therefore deprecated. If you still
need to specify custom options to change the way X behaves, you can
still do so by modifying configuration files under
/etc/X11/xorg.conf.d/
.
In SUSE Linux Enterprise Desktop 15 SP1 Wayland is included as an alternative to the X.org server. It can be selected during the installation.
Install the package xorg-docs
to
get more in-depth information about X11. man 5 xorg.conf
tells you more about the format of the manual configuration (if needed).
More information on the X11 development can be found on the project's home
page at http://www.x.org.
Drivers are found in xf86-video-*
packages, for
example xf86-video-ati
. Many of the drivers
delivered with these packages are described in detail in the related manual
page. For example, if you use the ati
driver, find more
information about this driver in man 4 ati
.
Information about third-party drivers is available in
/usr/share/doc/packages/<package_name>
.
For example, the documentation of x11-video-nvidiaG03
is available in
/usr/share/doc/packages/x11-video-nvidiaG04
after the package was installed.
Fonts in Linux can be categorized into two parts:
Contains a mathematical description as drawing instructions about the shape of a glyph. As such, each glyph can be scaled to arbitrary sizes without loss of quality. Before such a font (or glyph) can be used, the mathematical descriptions need to be transformed into a raster (grid). This process is called font rasterization. Font hinting (embedded inside the font) improves and optimizes the rendering result for a particular size. Rasterization and hinting is done with the FreeType library.
Common formats under Linux are PostScript Type 1 and Type 2, TrueType, and OpenType.
Consists of an array of pixels designed for a specific font size. Bitmap fonts are extremely fast and simple to render. However, compared to vector fonts, bitmap fonts cannot be scaled without losing quality. As such, these fonts are usually distributed in different sizes. These days, bitmap fonts are still used in the Linux console and sometimes in terminals.
Under Linux, Portable Compiled Format (PCF) or Glyph Bitmap Distribution Format (BDF) are the most common formats.
The appearance of these fonts can be influenced by two main aspects:
choosing a suitable font family,
rendering the font with an algorithm that achieves results comfortable for the receiver's eyes.
The last point is only relevant to vector fonts. Although the above two points are highly subjective, some defaults need to be created.
Linux font rendering systems consist of several libraries with different relations. The basic font rendering library is FreeType, which converts font glyphs of supported formats into optimized bitmap glyphs. The rendering process is controlled by an algorithm and its parameters (which may be subject to patent issues).
Every program or library which uses FreeType should consult the Fontconfig library. This library gathers font configuration from users and from the system. When a user amends their Fontconfig setting, this change will result in Fontconfig-aware applications.
More sophisticated OpenType shaping needed for scripts such as Arabic, Han or Phags-Pa and other higher level text processing is done using Harfbuzz or Pango.
To get an overview about which fonts are installed on your system, ask the
commands rpm
or fc-list
. Both will
give you a good answer, but may return a different list depending on system
and user configuration:
rpm
Invoke rpm
to see which software packages containing
fonts are installed on your system:
tux >
rpm -qa '*fonts*'
Every font package should satisfy this expression. However, the command
may return some false positives like fonts-config
(which is neither a font nor does it contain fonts).
fc-list
Invoke fc-list
to get an overview about what font
families can be accessed, whether they are installed on the system or in
your home:
tux >
fc-list ':' family
fc-list
The command fc-list
is a wrapper to the Fontconfig
library. It is possible to query a lot of interesting information from
Fontconfig—or, to be more precise, from its cache. See
man 1 fc-list
for more details.
If you want to know what an installed font family looks like, either use the
command ftview
(package
ft2demos
) or visit
http://fontinfo.opensuse.org/. For example, to display
the FreeMono font in 14 point, use ftview
like this:
tux >
ftview 14 /usr/share/fonts/truetype/FreeMono.ttf
If you need further information, go to http://fontinfo.opensuse.org/ to find out which styles (regular, bold, italic, etc.) and languages are supported.
To query which font is used when a pattern is given, use the
fc-match
command.
For example, if your pattern contains an already installed font,
fc-match
returns the file name, font family, and the
style:
tux >
fc-match 'Liberation Serif'
LiberationSerif-Regular.ttf: "Liberation Serif" "Regular"
If the desired font does not exist on your system, Fontconfig's matching rules take place and try to find the most similar fonts available. This means, your request is substituted:
tux >
fc-match 'Foo Family'
DejaVuSans.ttf: "DejaVu Sans" "Book"
Fontconfig supports aliases: a name is substituted with another family name. A typical example are the generic names such as “sans-serif”, “serif”, and “monospace”. These alias names can be substituted by real family names or even a preference list of family names:
tux >
for font in serif sans mono; do fc-match "$font" ; done
DejaVuSerif.ttf: "DejaVu Serif" "Book"
DejaVuSans.ttf: "DejaVu Sans" "Book"
DejaVuSansMono.ttf: "DejaVu Sans Mono" "Book"
The result may vary on your system, depending on which fonts are currently installed.
Fontconfig always returns a real family (if at least one is installed) according to the given request, as similar as possible. “Similarity” depends on Fontconfig's internal metrics and on the user's or administrator's Fontconfig settings.
To install a new font there are these major methods:
Manually install the font files such as *.ttf
or
*.otf
to a known font directory. If it needs to be
system-wide, use the standard directory
/usr/share/fonts
. For installation in your home
directory, use ~/.config/fonts
.
If you want to deviate from the standard directories, Fontconfig allows
you to choose another one. Let Fontconfig know by using the
<dir>
element, see
Section 21.2.5.2, “Diving into Fontconfig XML” for details.
Install fonts using zypper
. Lots of fonts are already
available as a package, be it on your SUSE distribution or in the M17N:fonts
repository. Add the repository to your list using the following command.
For example, to add a repository for SLE
15:
tux >
sudo
zypper ar https://download.opensuse.org/repositories/M17N:/fonts/SLE_15/
To search for your FONT_FAMILY_NAME use this command:
tux >
zypper se 'FONT_FAMILY_NAME*fonts'
Depending on the rendering medium, and font size, the result may be unsatisfactory. For example, an average monitor these days has a resolution of 100dpi which makes pixels too big and glyphs look clunky.
There are several algorithms available to deal with low resolutions, such as anti-aliasing (grayscale smoothing), hinting (fitting to the grid), or subpixel rendering (tripling resolution in one direction). These algorithms can also differ from one font format to another.
Subpixel rendering is not used in SUSE distributions. Although FreeType2 has support for this algorithm, it is covered by several patents expiring at the end of the year 2019. Therefore, setting subpixel rendering options in Fontconfig has no effect unless the system has a FreeType2 library with subpixel rendering compiled in.
Via Fontconfig, it is possible to select a rendering algorithms for every font individually or for a set of fonts.
sysconfig
#Edit source
SUSE Linux Enterprise Desktop comes with a sysconfig
layer above
Fontconfig. This is a good starting point for experimenting with font
configuration. To change the default settings, edit the configuration file
/etc/sysconfig/fonts-config
. (or use the YaST
sysconfig module). After you have edited the file, run
fonts-config
:
tux >
sudo
/usr/sbin/fonts-config
Restart the application to make the effect visible. Keep in mind the following issues:
A few applications do need not to be restarted. For example, Firefox re-reads Fontconfig configuration from time to time. Newly created or reloaded tabs get new font configurations later.
The fonts-config
script is called automatically after
every package installation or removal (if not, it is a bug of the font
software package).
Every sysconfig variable can be temporarily overridden by the
fonts-config
command line option. See
fonts-config --help
for details.
There are several sysconfig variables which can be altered. See
man 1 fonts-config
or the help page of the YaST
sysconfig module. The following variables are examples:
Consider FORCE_HINTSTYLE
,
FORCE_AUTOHINT
, FORCE_BW
,
FORCE_BW_MONOSPACE
,
USE_EMBEDDED_BITMAPS
and
EMBEDDED_BITMAP_LANGAGES
Use PREFER_SANS_FAMILIES
,
PREFER_SERIF_FAMILIES
,
PREFER_MONO_FAMILIES
and
SEARCH_METRIC_COMPATIBLE
The following list provides some configuration examples, sorted from the “most readable” fonts (more contrast) to “most beautiful” (more smoothed).
Prefer bitmap fonts via the PREFER_*_FAMILIES
variables. Follow the example in the help section for these variables.
Be aware that these fonts are rendered black and white, not smoothed and
that bitmap fonts are available in several sizes only. Consider using
SEARCH_METRIC_COMPATIBLE="no"
to disable metric compatibility-driven family name substitutions.
Scalable fonts rendered without antialiasing can result in a similar outcome to bitmap fonts, while maintaining font scalability. Use well hinted fonts like the Liberation families. Unfortunately, there is a lack of well hinted fonts though. Set the following variable to force this method:
FORCE_BW="yes"
Render monospaced fonts without antialiasing only, otherwise use default settings:
FORCE_BW_MONOSPACE="yes"
All fonts are rendered with antialiasing. Well hinted fonts will be
rendered with the byte code interpreter (BCI) and
the rest with autohinter (hintstyle=hintslight
).
Leave all relevant sysconfig variables to the default setting.
Use fonts in CFF format. They can be considered also more readable than
the default TrueType fonts given the current improvements in FreeType2.
Try them out by following the example of
PREFER_*_FAMILIES
. Possibly make them more dark and
bold with:
SEARCH_METRIC_COMPATIBLE="no"
as they are rendered by hintstyle=hintslight
by
default. Also consider using:
SEARCH_METRIC_COMPATIBLE="no"
Even for a well hinted font, use FreeType2's autohinter. That can lead to thicker, sometimes fuzzier letter shapes with lower contrast. Set the following variable to activate this:
FORCE_AUTOHINTER="yes"
Use FORCE_HINTSTYLE
to control the level of hinting.
Fontconfig's configuration format is the eXtensible Markup
Language (XML). These few examples are not a complete reference,
but a brief overview. Details and other inspiration can be found in
man 5 fonts-conf
or in
/etc/fonts/conf.d/
.
The central Fontconfig configuration file is
/etc/fonts/fonts.conf
, which—along other
work—includes the whole /etc/fonts/conf.d/
directory. To customize Fontconfig, there are two places where you can
insert your changes:
System-wide changes.
Edit the file /etc/fonts/local.conf
(by default, it
contains an empty fontconfig
element).
User-specific changes.
Edit the file ~/.config/fontconfig/fonts.conf
.
Place Fontconfig configuration files in the
~/.config/fontconfig/conf.d/
directory.
User-specific changes overwrite any system-wide settings.
The file ~/.fonts.conf
is marked as deprecated and
should not be used anymore. Use
~/.config/fontconfig/fonts.conf
instead.
Every configuration file needs to have a fontconfig
element. As such, the minimal file looks like this:
<?xml version="1.0"?> <!DOCTYPE fontconfig SYSTEM "fonts.dtd"> <fontconfig> <!-- Insert your changes here --> </fontconfig>
If the default directories are not enough, insert the
dir
element with the respective directory:
<dir>/usr/share/fonts2</dir>
Fontconfig searches recursively for fonts.
Font-rendering algorithms can be chosen with following Fontconfig snippet (see Example 21.1, “Specifying Rendering Algorithms”):
<match target="font"> <test name="family"> <string>FAMILY_NAME</string> </test> <edit name="antialias" mode="assign"> <bool>true</bool> </edit> <edit name="hinting" mode="assign"> <bool>true</bool> </edit> <edit name="autohint" mode="assign"> <bool>false</bool> </edit> <edit name="hintstyle" mode="assign"> <const>hintfull</const> </edit> </match>
Various properties of fonts can be tested. For example, the
<test>
element can test for the font family (as
shown in the example), size interval, spacing, font format, and others.
When abandoning <test>
completely, all
<edit>
elements will be applied to every font
(global change).
<alias> <family>Alegreya SC</family> <default> <family>serif</family> </default> </alias>
<alias> <family>serif</family> <prefer> <family>Droid Serif</family> </prefer> </alias>
<alias> <family>serif</family> <accept> <family>STIXGeneral</family> </accept> </alias>
The rules from Example 21.2, “Aliases and Family Name Substitutions” create a prioritized family list (PFL). Depending on the element, different actions are performed:
<default>
from
Rule 1
This rule adds a serif
family name at the
end of the PFL.
<prefer>
from
Rule 2
This rule adds “Droid Serif” just
before the first occurrence of serif
in
the PFL, whenever Alegreya SC
is in PFL.
<accept>
from Rule 3
This rule adds a “STIXGeneral” family name just
after the first occurrence of the serif
family name in the PFL.
Putting this together, when snippets occur in the order Rule 1 - Rule 2 - Rule 3 and the user requests “Alegreya SC”, then the PFL is created as depicted in Table 21.1, “Generating PFL from Fontconfig rules”.
In Fontconfig's metrics, the family name has the highest priority over other patterns, like style, size, etc. Fontconfig checks which family is currently installed on the system. If “Alegreya SC” is installed, then Fontconfig returns it. If not, it asks for “Droid Serif”, etc.
Be careful. When the order of Fontconfig snippets is changed, Fontconfig can return different results, as depicted in Table 21.2, “Results from Generating PFL from Fontconfig Rules with Changed Order”.
Think of the <default>
alias as a classification
or inclusion of this group (if not installed). As the example shows,
<default>
should always precede the
<prefer>
and <accept>
aliases of that group.
<default>
classification is not limited to the
generic aliases serif, sans-serif and monospace. See
/usr/share/fontconfig/conf.avail/30-metric-aliases.conf
for a complex example.
The following Fontconfig snippet in
Example 21.3, “Aliases and Family Name Substitutions” creates a
serif
group. Every family in this group could substitute
others when a former font is not installed.
<alias> <family>Alegreya SC</family> <default> <family>serif</family> </default> </alias> <alias> <family>Droid Serif</family> <default> <family>serif</family> </default> </alias> <alias> <family>STIXGeneral</family> <default> <family>serif</family> </default> </alias> <alias> <family>serif</family> <accept> <family>Droid Serif</family> <family>STIXGeneral</family> <family>Alegreya SC</family> </accept> </alias>
Priority is given by the order in the <accept>
alias. Similarly, stronger <prefer>
aliases can be
used.
Example 21.2, “Aliases and Family Name Substitutions” is expanded by Example 21.4, “Aliases and Family Names Substitutions”.
<alias> <family>serif</family> <accept> <family>Liberation Serif</family> </accept> </alias>
<alias> <family>serif</family> <prefer> <family>DejaVu Serif</family> </prefer> </alias>
The expanded configuration from Example 21.4, “Aliases and Family Names Substitutions” would lead to the following PFL evolution:
Order |
Current PFL |
---|---|
Request |
|
| |
| |
| |
| |
|
In case multiple <accept>
declarations for the
same generic name exist, the declaration that is parsed last
“wins”. If possible, do not use
<accept>
after
user (/etc/fonts/conf.d/*-user.conf
) when creating
a system-wide configuration.
In case multiple <prefer
declarations for the same
generic name exist, the declaration that is parsed last
“wins”. If possible, do not use
<prefer>
before user in the system-wide
configuration.
Every <prefer>
declaration overwrites
<accept>
declarations for the same generic
name. If the administrator wants to allow the user to use
<accept>
and not only
<prefer>
, the administrator should not use
<prefer>
in the system-wide configuration. On
the other hand, as users mostly use <prefer>
,
this should not have any detrimental effect. We also see the use of
<prefer>
in system-wide configurations.
dconf
System #Edit source
Configuration of the GNOME desktop is managed with
dconf
. It is a hierarchically structured database or
registry that allows users to modify their personal settings, and system
administrators to set default or mandatory values for all users.
dconf
replaces the gconf
system of
GNOME 2.
Use dconf-editor
to view the dconf
options with a graphical user interface. Use dconf
to
access and modify configuration options with the command line.
The GNOME Tweaks
tool provides an easy-to-use
user interface for additional configuration options beyond the
normal GNOME configuration. The tool can be started from the
GNOME application menu or from the command line with
gnome-tweak-tool
.
Global dconf
configuration parameters can be set
in the /etc/dconf/db/
directory. This includes
the configuration for GDM or locking certain configuration options
for users.
Use the following procedure as an example to create a system-wide configuration:
Create a new directory that ends with a .d
in
/etc/dconf/db/
. This directory can contain an
arbitrary amount of text files with configuration options. For this
example, create the file
/etc/dconf/db/network.d/00-proxy
with the
following content:
# This is a comment [system/proxy/http] host='10.0.0.1' enabled=true
Parse the new configuration directives into the dconf database format:
tux >
sudo
dconf update
Add the new network
configuration database to
the default user profile, by creating the file /etc/dconf/profiles/user
.
Then add the following content:
system-db:network
The file /etc/dconf/profiles/user
is a GNOME
default that will be used. Other profiles can be defined in the
environment variable DCONF_PROFILE
.
Optional: To lock the proxy configuration for users, create the file
/etc/dconf/db/network/locks/proxy
. Then add
a line to this file with the keys that may not be changed:
/system/proxy/http/host /system/proxy/http/enabled
You can use the graphical dconf-editor
to create a
profile with one user and then use dconf dump /
to list all configuration options. The configuration options can
then be stored in a global profile.
A detailed description of the global configuration is available at https://wiki.gnome.org/Projects/dconf/SystemAdministrators.
For more information, see http://help.gnome.org/admin/.
SUSE Prime is a tool for switching between onboard Intel graphical processing units (GPUs), and NVIDIA GPUs equipped with NVIDIA's "switchable graphics" Optimus technology. Optimus provides a mechanism for easily switching between an onboard Intel GPU and a discrete NVIDIA GPU. This is designed for running a laptop in a power-saving mode, or at maximum performance: use the Intel GPU to save power, and the NVIDIA GPU for 3D applications.
SUSE Prime is included in the SUSE Linux Enterprise Workstation Extension for SUSE Linux Enterprise 15 SP1.
SUSE Prime works only on systems running X11, not Wayland. If your system runs Wayland you may disable it and fall back to X11 (see Section 21.4.1, “Prerequisites”).
You must have a configured and working NVIDIA Optimus GPU using the NVIDIA drivers included in SUSE Linux Enterprise 15 SP1 (see Section 21.4.3, “Installing NVIDIA Drivers”), and an onboard Intel GPU. Bumblebee, the older switching tool for NVIDIA Optimus, must not be installed.
There must not be a /etc/X11/xorg.conf
file, and no
configuration files with active "ServerLayout", "Device" or "Screen"
sections in the /etc/X11/xorg.conf.d
directory.
SUSE Prime only works with X11. Use the loginctl
command to see if your system is using X11 or Wayland:
tux >
loginctl SESSION UID USER SEAT TTY 2 1000 tux seat0tux >
loginctl show-session 2|grep Type Type=x11
If your system uses Wayland, disable it by editing
/etc/gdm/custom.conf
, and un-commenting
WaylandEnable=false
. Then reboot.
Your NVIDIA graphics card should already be installed and working. If it is not, see Section 21.4.3, “Installing NVIDIA Drivers”.
Install the suse-prime package:
tux >
sudo
zypper install suse-prime
To switch your GPU run one of the following commands, then log out and log back in:
tux >
sudo
prime-select inteltux >
sudo
prime-select intel2tux >
sudo
prime-select nvidia
Use the intel
driver when it's the modesetting driver.
intel2
is for systems that use the
xf86-video-intel driver. You can get this information by
installing and running inxi:
tux >
inxi -G
Graphics: Device-1: Intel Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller
Display Server: x11(X.org 1.20.1 ) drivers: modesetting (unloaded: fbdev, vesa)
Resolution: 1920x1080@60.00hz
OpenGL: renderer: Mesa DRI Intel Haswell Desktop version: 4.5 Mesa 18.2.8
Which GPU is currently active?
tux >
sudo
/usr/sbin/prime-select get-current Driver configured: intel
If you need to identify your NVIDIA card so you know which driver to use, run the following command:
tux >
/sbin/lspci | grep VGA
List the available driver packages:
tux >
sudo
zypper se nvidia
Then install the drivers for your NVIDIA graphics card:
tux >
sudo
zypper se packagename
FUSE is the acronym for file system in user space.
This means you can configure and mount a file system as an unprivileged
user. Normally, you need to be
root
for this task. FUSE alone is
a kernel module. Combined with plug-ins, it allows you to extend FUSE to
access almost all file systems like remote SSH connections, ISO images, and
more.
Before you can use FUSE, you need to install the package
fuse
. Depending which file system
you want to use, you need additional plug-ins available as separate
packages.
Generally you do not need to configure FUSE. However, it is a good idea to
create a directory where all your mount points are combined. For example,
you can create a directory ~/mounts
and insert your
subdirectories for your different file systems there.
NTFS, the New Technology File System, is the default file system of Windows. Since under normal circumstances the unprivileged user cannot mount NTFS block devices using the external FUSE library, the process of mounting a Windows partition described below requires root privileges.
Become root
and install the
package ntfs-3g
.
Create a directory that is to be used as a mount point, for example
~/mounts/windows
.
Find out which Windows partition you need. Use YaST and start the
partitioner module to see which partition belongs to Windows, but do not
modify anything. Alternatively, become root
and execute
/sbin/fdisk
-l
. Look for partitions
with a partition type of HPFS/NTFS
.
Mount the partition in read-write mode. Replace the placeholder DEVICE with your respective Windows partition:
tux >
ntfs-3g /dev/DEVICE MOUNT POINT
To use your Windows partition in read-only mode, append -o
ro
:
tux >
ntfs-3g /dev/DEVICE MOUNT POINT -o ro
The command ntfs-3g
uses the current user (UID) and
group (GID) to mount the given device. If you want to set the write
permissions to a different user, use the command id
USER
to get the output of the UID and GID values. Set it
with:
root #
id tux
uid=1000(tux) gid=100(users) groups=100(users),16(dialout),33(video)
ntfs-3g /dev/DEVICE MOUNT POINT -o uid=1000,gid=100
Find additional options in the man page.
To unmount the resource, run fusermount -u
MOUNT POINT.
For more information, see the home page of FUSE at https://github.com/libfuse/libfuse.
Although Linux is a monolithic kernel, it can be extended using kernel modules. These are special objects that can be inserted into the kernel and removed on demand. In practical terms, kernel modules make it possible to add and remove drivers and interfaces that are not included in the kernel itself. Linux provides several commands for managing kernel modules.
Use the lsmod
command to view what kernel modules are
currently loaded. The output of the command may look as follows:
tux >
lsmod
Module Size Used by
snd_usb_audio 188416 2
snd_usbmidi_lib 36864 1 snd_usb_audio
hid_plantronics 16384 0
snd_rawmidi 36864 1 snd_usbmidi_lib
snd_seq_device 16384 1 snd_rawmidi
fuse 106496 3
nfsv3 45056 1
nfs_acl 16384 1 nfsv3
The output is divided into three columns. The Module
column lists the names
of the loaded modules, while the Size
column displays the size of each
module. The Used by
column shows the number of referring
modules and their names. Note that this list may be incomplete.
To view detailed information about a specific kernel module, use the
modinfo MODULE_NAME
command, where
MODULE_NAME is the name of the desired kernel
module. Note that the modinfo
binary resides in the
/sbin
directory that is not in the user's PATH
environment variable. This means that you must specify the full path to the
binary when running modinfo
command as a regular user:
tux >
/sbin/modinfo kvm
filename: /lib/modules/4.4.57-18.3-default/kernel/arch/x86/kvm/kvm.ko
license: GPL
author: Qumranet
srcversion: BDFD8098BEEA517CB75959B
depends: irqbypass
intree: Y
vermagic: 4.4.57-18.3-default SMP mod_unload modversions
signer: openSUSE Secure Boot Signkey
sig_key: 03:32:FA:9C:BF:0D:88:BF:21:92:4B:0D:E8:2A:09:A5:4D:5D:EF:C8
sig_hashalgo: sha256
parm: ignore_msrs:bool
parm: min_timer_period_us:uint
parm: kvmclock_periodic_sync:bool
parm: tsc_tolerance_ppm:uint
parm: lapic_timer_advance_ns:uint
parm: halt_poll_ns:uint
parm: halt_poll_ns_grow:int
parm: halt_poll_ns_shrink:int
While it is possible to use insmod
and
rmmod
to add and remove kernel modules, it is recommended to use the
modprobe
tool instead. modprobe
offers several
important advantages, including automatic dependency resolution and
blacklisting.
When used without any parameters, the modprobe
command installs a specified kernel module. modprobe
must be run with root privileges:
tux >
sudo
modprobe acpi
To remove a kernel module, use the -r
parameter:
tux >
sudo
modprobe -r acpi
Instead of loading kernel modules manually, you can load them
automatically during the boot process using the
system-modules-load.service
service. To enable a
kernel module, add a .conf
file to the
/etc/modules-load.d/
directory. It is good practice
to give the configuration file the same name as the module, for example:
/etc/modules-load.d/rt2800usb.conf
The configuration file must contain the name of the desired kernel
module (for example, rt2800usb
).
The described technique allows you to load kernel modules without any
parameters. If you need to load a kernel module with specific options,
add a configuration file to the /etc/modprobe.d/
directory instead. The file must have the .conf
extension. The name of the file should adhere to the following naming convention:
priority-modulename.conf
, for example:
50-thinkfan.conf
. The configuration file must
contain the name of the kernel module and the desired parameters. You can use the
example command below to create a configuration file containing the name of the kernel module and its parameters:
tux >
echo "options thinkpad_acpi fan_control=1" | sudo tee /etc/modprobe.d/thinkfan.conf
Most kernel modules are loaded by the system automatically when a
device is detected or user space requests specific
functionality. Thus, adding modules manually to
/etc/modules-load.d/
is rarely required.
Blacklisting a kernel module prevents it from loading during the boot
process. This can be useful when you want to disable a module that you
suspect is causing problems on your system. Note that you can still load
blacklisted kernel modules manually using the
insmod
or modprobe
tools.
To blacklist a module, add the
blacklist MODULE_NAME
line
to the /etc/modprobe.d/50-blacklist.conf
file. For example:
blacklist nouveau
Run the mkinitrd
command as root to generate a new initrd
image, then reboot your machine. These steps can be performed using the following command:
tux >
su
echo "blacklist nouveau" >> /etc/modprobe.d/50-blacklist.conf && mkinitrd && reboot
To disable a kernel module temporarily only, blacklist it on-the-fly during the boot. To do this, press the E key when you see the boot screen. This drops you into a minimal editor that allows you to modify boot parameters. Locate the line that looks as follows:
linux /boot/vmlinuz...splash= silent quiet showopts
Add the
modprobe.blacklist=MODULE_NAME
command to the end of the line. For example:
linux /boot/vmlinuz...splash= silent quiet showopts modprobe.blacklist=nouveau
Press F10 or Ctrl–X to boot with the specified configuration.
To blacklist a kernel module permanently via GRUB, open the
/etc/default/grub
file for editing, and add the
modprobe.blacklist=MODULE_NAME
option to the GRUB_CMD_LINUX
command. Then run the
sudo grub2-mkconfig -o /boot/grub2/grub.cfg
command to enable
the changes.
udev
#Edit source/dev
Directoryuevents
and udev
udev
Daemonudev
Rulesudev
The kernel can add or remove almost any device in a running system. Changes
in the device state (whether a device is plugged in or removed) need to be
propagated to user space. Devices need to be configured when they are
plugged in and recognized. Users of a certain device need to be informed
about any changes in this device's recognized state.
udev
provides the needed
infrastructure to dynamically maintain the device node files and symbolic
links in the /dev
directory.
udev
rules provide a way to plug
external tools into the kernel device event processing. This allows you to
customize udev
device handling by adding certain scripts to execute as part of kernel device
handling, or request and import additional data to evaluate during device
handling.
/dev
Directory #Edit source
The device nodes in the /dev
directory provide access
to the corresponding kernel devices. With
udev
, the /dev
directory reflects the current state of the kernel. Every kernel device has
one corresponding device file. If a device is disconnected from the system,
the device node is removed.
The content of the /dev
directory is kept on a
temporary file system and all files are rendered at every system start-up.
Manually created or modified files do not, by design, survive a reboot.
Static files and directories that should always be in the
/dev
directory regardless of the state of the
corresponding kernel device can be created with systemd-tmpfiles. The
configuration files are found in /usr/lib/tmpfiles.d/
and /etc/tmpfiles.d/
; for more information, see the
systemd-tmpfiles(8)
man page.
uevents
and udev
#Edit source
The required device information is exported by the
sysfs
file system. For every
device the kernel has detected and initialized, a directory with the device
name is created. It contains attribute files with device-specific
properties.
Every time a device is added or removed, the kernel sends a uevent to notify
udev
of the change. The
udev
daemon reads and parses all
rules from the /usr/lib/udev/rules.d/*.rules
and
/etc/udev/rules.d/*.rules
files at start-up and keeps
them in memory. If rules files are changed, added or removed, the daemon can
reload their in-memory representation with the command
udevadm control --reload
. For more details on
udev
rules and their syntax, refer
to Section 24.6, “Influencing Kernel Device Event Handling with udev
Rules”.
Every received event is matched against the set of provides rules. The rules
can add or change event environment keys, request a specific name for the
device node to create, add symbolic links pointing to the node or add
programs to run after the device node is created. The driver core
uevents
are received from a kernel
netlink socket.
The kernel bus drivers probe for devices. For every detected device, the
kernel creates an internal device structure while the driver core sends a
uevent to the udev
daemon. Bus
devices identify themselves by a specially-formatted ID, which tells what
kind of device it is. Usually these IDs consist of vendor and product ID and
other subsystem-specific values. Every bus has its own scheme for these IDs,
called MODALIAS
. The kernel takes the device information,
composes a MODALIAS
ID string from it and sends that string
along with the event. For a USB mouse, it looks like this:
MODALIAS=usb:v046DpC03Ed2000dc00dsc00dp00ic03isc01ip02
Every device driver carries a list of known aliases for devices it can
handle. The list is contained in the kernel module file itself. The program
depmod reads the ID lists and creates the file
modules.alias
in the kernel's
/lib/modules
directory for all currently available
modules. With this infrastructure, module loading is as easy as calling
modprobe
for every event that carries a
MODALIAS
key. If modprobe $MODALIAS
is
called, it matches the device alias composed for the device with the aliases
provided by the modules. If a matching entry is found, that module is
loaded. All this is automatically triggered by
udev
.
All device events happening during the boot process before the
udev
daemon is running are lost,
because the infrastructure to handle these events resides on the root file
system and is not available at that time. To cover that loss, the kernel
provides a uevent
file located in the device directory
of every device in the sysfs
file system. By writing add
to that file, the kernel
resends the same event as the one lost during boot. A simple loop over all
uevent
files in /sys
triggers all
events again to create the device nodes and perform device setup.
As an example, a USB mouse present during boot may not be initialized by the
early boot logic, because the driver is not available at that time. The
event for the device discovery was lost and failed to find a kernel module
for the device. Instead of manually searching for connected
devices, udev
requests all device
events from the kernel after the root file system is available, so the event
for the USB mouse device runs again. Now it finds the kernel module on the
mounted root file system and the USB mouse can be initialized.
From user space, there is no visible difference between a device coldplug sequence and a device discovery during runtime. In both cases, the same rules are used to match and the same configured programs are run.
udev
Daemon #Edit source
The program udevadm monitor
can be used to visualize the
driver core events and the timing of the
udev
event processes.
UEVENT[1185238505.276660] add /devices/pci0000:00/0000:00:1d.2/usb3/3-1 (usb) UDEV [1185238505.279198] add /devices/pci0000:00/0000:00:1d.2/usb3/3-1 (usb) UEVENT[1185238505.279527] add /devices/pci0000:00/0000:00:1d.2/usb3/3-1/3-1:1.0 (usb) UDEV [1185238505.285573] add /devices/pci0000:00/0000:00:1d.2/usb3/3-1/3-1:1.0 (usb) UEVENT[1185238505.298878] add /devices/pci0000:00/0000:00:1d.2/usb3/3-1/3-1:1.0/input/input10 (input) UDEV [1185238505.305026] add /devices/pci0000:00/0000:00:1d.2/usb3/3-1/3-1:1.0/input/input10 (input) UEVENT[1185238505.305442] add /devices/pci0000:00/0000:00:1d.2/usb3/3-1/3-1:1.0/input/input10/mouse2 (input) UEVENT[1185238505.306440] add /devices/pci0000:00/0000:00:1d.2/usb3/3-1/3-1:1.0/input/input10/event4 (input) UDEV [1185238505.325384] add /devices/pci0000:00/0000:00:1d.2/usb3/3-1/3-1:1.0/input/input10/event4 (input) UDEV [1185238505.342257] add /devices/pci0000:00/0000:00:1d.2/usb3/3-1/3-1:1.0/input/input10/mouse2 (input)
The UEVENT
lines show the events the kernel has sent over
netlink. The UDEV
lines show the finished
udev
event handlers. The timing is
printed in microseconds. The time between UEVENT
and
UDEV
is the time
udev
took to process this event or
the udev
daemon has delayed its
execution to synchronize this event with related and already running events.
For example, events for hard disk partitions always wait for the main disk
device event to finish, because the partition events may rely on the data
that the main disk event has queried from the hardware.
udevadm monitor --env
shows the complete event
environment:
ACTION=add DEVPATH=/devices/pci0000:00/0000:00:1d.2/usb3/3-1/3-1:1.0/input/input10 SUBSYSTEM=input SEQNUM=1181 NAME="Logitech USB-PS/2 Optical Mouse" PHYS="usb-0000:00:1d.2-1/input0" UNIQ="" EV=7 KEY=70000 0 0 0 0 REL=103 MODALIAS=input:b0003v046DpC03Ee0110-e0,1,2,k110,111,112,r0,1,8,amlsfw
udev
also sends messages to syslog.
The default syslog priority that controls which messages are sent to syslog
is specified in the udev
configuration file /etc/udev/udev.conf
. The log
priority of the running daemon can be changed with udevadm control
--log_priority=
LEVEL/NUMBER.
udev
Rules #Edit source
A udev
rule can match any property
the kernel adds to the event itself or any information that the kernel
exports to sysfs
. The rule can also request additional
information from external programs. Events are matched against all rules
provided in the directories /usr/lib/udev/rules.d/
(for default rules) and /etc/udev/rules.d
(system-specific configuration).
Every line in the rules file contains at least one key value pair. There are
two kinds of keys, match and assignment keys. If all match keys match their
values, the rule is applied and the assignment keys are assigned the
specified value. A matching rule may specify the name of the device node,
add symbolic links pointing to the node or run a specified program as part
of the event handling. If no matching rule is found, the default device node
name is used to create the device node. Detailed information about the rule
syntax and the provided keys to match or import data are described in the
udev
man page. The following
example rules provide a basic introduction to
udev
rule syntax. The example rules
are all taken from the udev
default
rule set /usr/lib/udev/rules.d/50-udev-default.rules
.
udev
Rules ## console KERNEL=="console", MODE="0600", OPTIONS="last_rule" # serial devices KERNEL=="ttyUSB*", ATTRS{product}=="[Pp]alm*Handheld*", SYMLINK+="pilot" # printer SUBSYSTEM=="usb", KERNEL=="lp*", NAME="usb/%k", SYMLINK+="usb%k", GROUP="lp" # kernel firmware loader SUBSYSTEM=="firmware", ACTION=="add", RUN+="firmware.sh"
The console
rule consists of three keys: one match
key (KERNEL
) and two assign keys
(MODE
, OPTIONS
). The
KERNEL
match rule searches the device list for any items
of the type console
. Only exact matches are valid and
trigger this rule to be executed. The MODE
key assigns
special permissions to the device node, in this case, read and write
permissions to the owner of this device only. The OPTIONS
key makes this rule the last rule to be applied to any device of this type.
Any later rule matching this particular device type does not have any
effect.
The serial devices
rule is not available in
50-udev-default.rules
anymore, but it is still worth
considering. It consists of two match keys (KERNEL
and
ATTRS
) and one assign key (SYMLINK
).
The KERNEL
key searches for all devices of the
ttyUSB
type. Using the *
wild card,
this key matches several of these devices. The second match key,
ATTRS
, checks whether the product
attribute file in sysfs
for any ttyUSB
device contains a certain string. The assign key
(SYMLINK
) triggers the addition of a symbolic link to
this device under /dev/pilot
. The operator used in this
key (+=
) tells
udev
to additionally perform this
action, even if previous or later rules add other symbolic links. As this
rule contains two match keys, it is only applied if both conditions are met.
The printer
rule deals with USB printers and
contains two match keys which must both apply to get the entire rule applied
(SUBSYSTEM
and KERNEL
). Three assign
keys deal with the naming for this device type (NAME
),
the creation of symbolic device links (SYMLINK
) and the
group membership for this device type (GROUP
). Using the
*
wild card in the KERNEL
key makes it
match several lp
printer devices. Substitutions are used
in both, the NAME
and the SYMLINK
keys
to extend these strings by the internal device name. For example, the
symbolic link to the first lp
USB printer would read
/dev/usblp0
.
The kernel firmware loader
rule makes
udev
load additional firmware by an
external helper script during runtime. The SUBSYSTEM
match key searches for the firmware
subsystem. The
ACTION
key checks whether any device belonging to the
firmware
subsystem has been added. The
RUN+=
key triggers the execution of the
firmware.sh
script to locate the firmware that is to be
loaded.
Some general characteristics are common to all rules:
Each rule consists of one or more key value pairs separated by a comma.
A key's operation is determined by the operator.
udev
rules support several
operators.
Each given value must be enclosed by quotation marks.
Each line of the rules file represents one rule. If a rule is longer than
one line, use \
to join the different lines as you
would do in shell syntax.
udev
rules support a shell-style
pattern that matches the *
, ?
, and
[]
patterns.
udev
rules support substitutions.
udev
Rules #Edit sourceCreating keys you can choose from several operators, depending on the type of key you want to create. Match keys will normally be used to find a value that either matches or explicitly mismatches the search value. Match keys contain either of the following operators:
==
Compare for equality. If the key contains a search pattern, all results matching this pattern are valid.
!=
Compare for non-equality. If the key contains a search pattern, all results matching this pattern are valid.
Any of the following operators can be used with assign keys:
=
Assign a value to a key. If the key previously consisted of a list of values, the key resets and only the single value is assigned.
+=
Add a value to a key that contains a list of entries.
:=
Assign a final value. Disallow any later change by later rules.
udev
Rules #Edit source
udev
rules support the use of
placeholders and substitutions. Use them in a similar fashion as you would
do in any other scripts. The following substitutions can be used with
udev
rules:
%r
, $root
The device directory, /dev
by default.
%p
, $devpath
The value of DEVPATH
.
%k
, $kernel
The value of KERNEL
or the internal device name.
%n
, $number
The device number.
%N
, $tempnode
The temporary name of the device file.
%M
, $major
The major number of the device.
%m
, $minor
The minor number of the device.
%s{ATTRIBUTE}
,
$attr{ATTRIBUTE}
The value of a sysfs
attribute (specified by
ATTRIBUTE).
%E{VARIABLE}
,
$env{VARIABLE}
The value of an environment variable (specified by VARIABLE).
%c
, $result
The output of PROGRAM
.
%%
The %
character.
$$
The $
character.
udev
Match Keys #Edit source
Match keys describe conditions that must be met before a
udev
rule can be applied. The
following match keys are available:
ACTION
The name of the event action, for example, add
or
remove
when adding or removing a device.
DEVPATH
The device path of the event device, for example,
DEVPATH=/bus/pci/drivers/ipw3945
to search for all
events related to the ipw3945 driver.
KERNEL
The internal (kernel) name of the event device.
SUBSYSTEM
The subsystem of the event device, for example,
SUBSYSTEM=usb
for all events related to USB devices.
ATTR{FILENAME}
sysfs
attributes of the
event device. To match a string contained in the
vendor
attribute file name, you could use
ATTR{vendor}=="On[sS]tream"
, for example.
KERNELS
Let udev
search the device path
upward for a matching device name.
SUBSYSTEMS
Let udev
search the device path
upward for a matching device subsystem name.
DRIVERS
Let udev
search the device path
upward for a matching device driver name.
ATTRS{FILENAME}
Let udev
search the device path
upward for a device with matching
sysfs
attribute values.
ENV{KEY}
The value of an environment variable, for example,
ENV{ID_BUS}="ieee1394
to search for all events
related to the FireWire bus ID.
PROGRAM
Let udev
execute an external
program. To be successful, the program must return with exit code zero.
The program's output, printed to STDOUT, is available to the
RESULT
key.
RESULT
Match the output string of the last PROGRAM
call.
Either include this key in the same rule as the
PROGRAM
key or in a later one.
udev
Assign Keys #Edit source
In contrast to the match keys described above, assign keys do not describe
conditions that must be met. They assign values, names and actions to the
device nodes maintained by udev
.
NAME
The name of the device node to be created. After a rule has set a node
name, all other rules with a NAME
key for this node
are ignored.
SYMLINK
The name of a symbolic link related to the node to be created. Multiple matching rules can add symbolic links to be created with the device node. You can also specify multiple symbolic links for one node in one rule using the space character to separate the symbolic link names.
OWNER, GROUP, MODE
The permissions for the new device node. Values specified here overwrite anything that has been compiled in.
ATTR{KEY}
Specify a value to be written to a
sysfs
attribute of the event
device. If the ==
operator is used, this key is also
used to match against the value of a
sysfs
attribute.
ENV{KEY}
Tell udev
to export a variable
to the environment. If the ==
operator is used, this
key is also used to match against an environment variable.
RUN
Tell udev
to add a program to
the list of programs to be executed for this device. Keep in mind to
restrict this to very short tasks to avoid blocking further events for
this device.
LABEL
Add a label where a GOTO
can jump to.
GOTO
Tell udev
to skip several
rules and continue with the one that carries the label referenced by the
GOTO
key.
IMPORT{TYPE}
Load variables into the event environment such as the output of an
external program. udev
imports
variables of several types. If no type is specified,
udev
tries to determine the
type itself based on the executable bit of the file permissions.
program
tells
udev
to execute an external
program and import its output.
file
tells
udev
to import a text file.
parent
tells
udev
to import the stored
keys from the parent device.
WAIT_FOR_SYSFS
Tells udev
to wait for the
specified sysfs
file to be
created for a certain device. For example,
WAIT_FOR_SYSFS="ioerr_cnt"
informs
udev
to wait until the
ioerr_cnt
file has been created.
OPTIONS
The OPTION
key may have several values:
last_rule
tells
udev
to ignore all later
rules.
ignore_device
tells
udev
to ignore this event
completely.
ignore_remove
tells
udev
to ignore all later
remove events for the device.
all_partitions
tells
udev
to create device nodes
for all available partitions on a block device.
The dynamic device directory and the
udev
rules infrastructure make it
possible to provide stable names for all disk devices—regardless of
their order of recognition or the connection used for the device. Every
appropriate block device the kernel creates is examined by tools with
special knowledge about certain buses, drive types or file systems. Along
with the dynamic kernel-provided device node name,
udev
maintains classes of
persistent symbolic links pointing to the device:
/dev/disk |-- by-id | |-- scsi-SATA_HTS726060M9AT00_MRH453M4HWHG7B -> ../../sda | |-- scsi-SATA_HTS726060M9AT00_MRH453M4HWHG7B-part1 -> ../../sda1 | |-- scsi-SATA_HTS726060M9AT00_MRH453M4HWHG7B-part6 -> ../../sda6 | |-- scsi-SATA_HTS726060M9AT00_MRH453M4HWHG7B-part7 -> ../../sda7 | |-- usb-Generic_STORAGE_DEVICE_02773 -> ../../sdd | `-- usb-Generic_STORAGE_DEVICE_02773-part1 -> ../../sdd1 |-- by-label | |-- Photos -> ../../sdd1 | |-- SUSE10 -> ../../sda7 | `-- devel -> ../../sda6 |-- by-path | |-- pci-0000:00:1f.2-scsi-0:0:0:0 -> ../../sda | |-- pci-0000:00:1f.2-scsi-0:0:0:0-part1 -> ../../sda1 | |-- pci-0000:00:1f.2-scsi-0:0:0:0-part6 -> ../../sda6 | |-- pci-0000:00:1f.2-scsi-0:0:0:0-part7 -> ../../sda7 | |-- pci-0000:00:1f.2-scsi-1:0:0:0 -> ../../sr0 | |-- usb-02773:0:0:2 -> ../../sdd | |-- usb-02773:0:0:2-part1 -> ../../sdd1 `-- by-uuid |-- 159a47a4-e6e6-40be-a757-a629991479ae -> ../../sda7 |-- 3e999973-00c9-4917-9442-b7633bd95b9e -> ../../sda6 `-- 4210-8F8C -> ../../sdd1
udev
#Edit source/sys/*
Virtual file system provided by the Linux kernel, exporting all currently
known devices. This information is used by
udev
to create device nodes in
/dev
/dev/*
Dynamically created device nodes and static content created with
systemd-tmpfiles; for more information, see the
systemd-tmpfiles(8)
man page.
The following files and directories contain the crucial elements of the
udev
infrastructure:
/etc/udev/udev.conf
Main udev
configuration file.
/etc/udev/rules.d/*
System-specific udev
event
matching rules. You can add custom rules here to modify or override
the default rules from /usr/lib/udev/rules.d/*
.
Files are parsed in alphanumeric order. Rules from files with a higher priority modify or override rules with lower priority. The lower the number, the higher the priority.
/usr/lib/udev/rules.d/*
Default udev
event matching
rules. The files in this directory are owned by packages and will be
overwritten by updates. Do not add, remove or edit files here, use
/etc/udev/rules.d
instead.
/usr/lib/udev/*
Helper programs called from udev
rules.
/usr/lib/tmpfiles.d/
and
/etc/tmpfiles.d/
Responsible for static /dev
content.
For more information about the udev
infrastructure, refer to the following man pages:
udev
General information about udev
,
keys, rules and other important configuration issues.
udevadm
udevadm
can be used to control the runtime behavior of
udev
, request kernel events,
manage the event queue and provide simple debugging mechanisms.
udevd
Information about the udev
event
managing daemon.
This chapter starts with information about various software packages, the
virtual consoles and the keyboard layout. We talk about software components
like bash
,
cron
and
logrotate
, because they were
changed or enhanced during the last release cycles. Even if they are small
or considered of minor importance, users should change their default
behavior, because these components are often closely coupled with the
system. The chapter concludes with a section about language and
country-specific settings (I18N and L10N).
The following chapter provides basic information about the following tools: bash
, cron
, logrotate
, locate
, ulimit
and free
.
bash
Package and /etc/profile
#Edit sourceBash is the default system shell. When used as a login shell, it reads several initialization files. Bash processes them in the order they appear in this list:
/etc/profile
~/.profile
/etc/bash.bashrc
~/.bashrc
Make custom settings in ~/.profile
or
~/.bashrc
. To ensure the correct processing of these
files, it is necessary to copy the basic settings from
/etc/skel/.profile
or
/etc/skel/.bashrc
into the home directory of the user.
It is recommended to copy the settings from /etc/skel
after an update. Execute the following shell commands to prevent the loss of
personal adjustments:
tux >
mv ~/.bashrc ~/.bashrc.oldtux >
cp /etc/skel/.bashrc ~/.bashrctux >
mv ~/.profile ~/.profile.oldtux >
cp /etc/skel/.profile ~/.profile
Then copy personal adjustments back from the *.old
files.
Use cron
to automatically run
commands in the background at predefined times. cron
uses specially formatted time tables, and
the tool comes with several default ones. Users can also specify custom
tables, if needed.
The cron tables are located in /var/spool/cron/tabs
.
/etc/crontab
serves as a systemwide cron table. Enter
the user name to run the command directly after the time table and before
the command. In Example 25.1, “Entry in /etc/crontab”,
root
is entered. Package-specific
tables, located in /etc/cron.d
, have the same format.
See the cron
man page (man cron
).
1-59/5 * * * * root test -x /usr/sbin/atrun && /usr/sbin/atrun
You cannot edit /etc/crontab
by calling the command
crontab -e
. This file must be loaded directly into an
editor, then modified and saved.
Several packages install shell scripts to the directories
/etc/cron.hourly
, /etc/cron.daily
,
/etc/cron.weekly
and
/etc/cron.monthly
, whose execution is controlled by
/usr/lib/cron/run-crons
.
/usr/lib/cron/run-crons
is run every 15 minutes from
the main table (/etc/crontab
). This guarantees that
processes that may have been neglected can be run at the proper time.
To run the hourly
, daily
or other
periodic maintenance scripts at custom times, remove the time stamp files
regularly using /etc/crontab
entries (see
Example 25.2, “/etc/crontab: Remove Time Stamp Files”, which removes the
hourly
one before every full hour, the
daily
one once a day at 2:14 a.m., etc.).
59 * * * * root rm -f /var/spool/cron/lastrun/cron.hourly 14 2 * * * root rm -f /var/spool/cron/lastrun/cron.daily 29 2 * * 6 root rm -f /var/spool/cron/lastrun/cron.weekly 44 2 1 * * root rm -f /var/spool/cron/lastrun/cron.monthly
Or you can set DAILY_TIME
in
/etc/sysconfig/cron
to the time at which
cron.daily
should start. The setting of
MAX_NOT_RUN
ensures that the daily tasks get triggered to
run, even if the user did not turn on the computer at the specified
DAILY_TIME
for a longer time. The maximum value of
MAX_NOT_RUN
is 14 days.
The daily system maintenance jobs are distributed to various scripts for
reasons of clarity. They are contained in the package
aaa_base
.
/etc/cron.daily
contains, for example, the components
suse.de-backup-rpmdb
,
suse.de-clean-tmp
or
suse.de-cron-local
.
To avoid the mail-flood caused by cron status messages, the default value of
SEND_MAIL_ON_NO_ERROR
in
/etc/sysconfig/cron
is set to "no
"
for new installations. Even with this setting to "no
",
cron data output will still be sent to the MAILTO
address, as documented in the cron man page.
In the update case it is recommended to set these values according to your needs.
There are several system services (daemons) that, along
with the kernel itself, regularly record the system status and specific
events onto log files. This way, the administrator can regularly check the
status of the system at a certain point in time, recognize errors or faulty
functions and troubleshoot them with pinpoint precision. These log files are
normally stored in /var/log
as specified by FHS and grow
on a daily basis. The logrotate
package helps
control the growth of these files. For more details refer to Book “System Analysis and Tuning Guide”, Chapter 3 “Analyzing and Managing System Log Files”, Section 3.3 “Managing Log Files with logrotate
”.
locate
Command #Edit source
locate
, a command for quickly finding files, is not
included in the standard scope of installed software. If desired, install
the package mlocate
, the successor of the package
findutils-locate
. The
updatedb
process is started
automatically every night or about 15 minutes after booting the system.
ulimit
Command #Edit source
With the ulimit
(user limits)
command, it is possible to set limits for the use of system resources and to
have these displayed. ulimit
is especially useful for
limiting available memory for applications. With this, an application can be
prevented from co-opting too much of the system resources and slowing or
even hanging up the operating system.
ulimit
can be used with various options. To limit memory
usage, use the options listed in Table 25.1, “ulimit
: Setting Resources for the User”.
ulimit
: Setting Resources for the User #
|
The maximum resident set size |
|
The maximum amount of virtual memory available to the shell |
|
The maximum size of the stack |
|
The maximum size of core files created |
|
All current limits are reported |
Systemwide default entries are set in /etc/profile
.
Editing this file directly is not recommended, because changes will be
overwritten during system upgrades. To customize systemwide profile
settings, use /etc/profile.local
. Per-user settings
should be made in
~USER/.profile
.
ulimit
: Settings in ~/.bashrc
## Limits maximum resident set size (physical memory): ulimit -m 98304 # Limits of virtual memory: ulimit -v 98304
Memory allocations must be specified in KB. For more detailed information,
see man bash
.
ulimit
Support
Not all shells support ulimit
directives. PAM (for
example, pam_limits
) offers comprehensive adjustment
possibilities as an alternative to ulimit
.
free
Command #Edit source
The free
command displays the total amount of free and
used physical memory and swap space in the system and the buffers and
cache consumed by the kernel. The concept of available
RAM dates back to before the days of unified memory management.
The slogan free memory is bad memory applies well to
Linux. As a result, Linux has always made the effort to balance out caches
without actually allowing free or unused memory.
The kernel does not have direct knowledge of any applications or user data.
Instead, it manages applications and user data in a page
cache. If memory runs short, parts of it are written to the swap
partition or to files, from which they can initially be read using the
mmap
command (see man mmap
).
The kernel also contains other caches, such as the slab
cache, where the caches used for network access are stored. This
may explain the differences between the counters in
/proc/meminfo
. Most, but not all, of them can be
accessed via /proc/slabinfo
.
However, if your goal is to find out how much RAM is currently being used,
find this information in /proc/meminfo
.
For some GNU applications (such as tar), the man pages are no longer
maintained. For these commands, use the --help
option to
get a quick overview of the info pages, which provide more in-depth
instructions. Info
is GNU's hypertext system. Read an introduction to this system by entering
info
info
. Info pages can be viewed with
Emacs by entering emacs
-f info
or
directly in a console with info
. You can also use tkinfo,
xinfo or the help system to view info pages.
man
Command #Edit source
To read a man page enter man
MAN_PAGE. If a man page with the same name exists
in different sections, they will all be listed with the corresponding
section numbers. Select the one to display. If you do not enter a section
number within a few seconds, the first man page will be displayed.
To change this to the default system behavior, set
MAN_POSIXLY_CORRECT=1
in a shell initialization file such
as ~/.bashrc
.
GNU Emacs is a complex work environment. The following sections cover the configuration files processed when GNU Emacs is started. More information is available at http://www.gnu.org/software/emacs/.
On start-up, Emacs reads several files containing the settings of the user,
system administrator and distributor for customization or preconfiguration.
The initialization file ~/.emacs
is installed to the
home directories of the individual users from /etc/skel
.
.emacs
, in turn, reads the file
/etc/skel/.gnu-emacs
. To customize the program, copy
.gnu-emacs
to the home directory (with cp
/etc/skel/.gnu-emacs ~/.gnu-emacs
) and make the desired settings
there.
.gnu-emacs
defines the file
~/.gnu-emacs-custom
as custom-file
.
If users make settings with the customize
options in
Emacs, the settings are saved to ~/.gnu-emacs-custom
.
With SUSE Linux Enterprise Desktop, the emacs
package installs the file site-start.el
in the directory
/usr/share/emacs/site-lisp
. The file
site-start.el
is loaded before the initialization file
~/.emacs
. Among other things,
site-start.el
ensures that special configuration files
distributed with Emacs add-on packages, such as
psgml
, are loaded automatically.
Configuration files of this type are located in
/usr/share/emacs/site-lisp
, too, and always begin with
suse-start-
. The local system administrator can specify
systemwide settings in default.el
.
More information about these files is available in the Emacs info file under
Init File: info:/emacs/InitFile
.
Information about how to disable the loading of these files (if necessary) is
also provided at this location.
The components of Emacs are divided into several packages:
The base package emacs
.
emacs-x11
(usually installed):
the program with X11 support.
emacs-nox
: the program
without X11 support.
emacs-info
: online documentation
in info format.
emacs-el
: the uncompiled library
files in Emacs Lisp. These are not required at runtime.
Numerous add-on packages can be installed if needed:
emacs-auctex
(LaTeX),
psgml
(SGML and XML),
gnuserv
(client and server
operation) and others.
Linux is a multiuser and multitasking system. The advantages of these features can be appreciated even on a stand-alone PC system. In text mode, there are six virtual consoles available. Switch between them using Alt–F1 through Alt–F6. The seventh console is reserved for X and the tenth console shows kernel messages.
To switch to a console from X without shutting it down, use Ctrl–Alt–F1 to Ctrl–Alt–F6. To return to X, press Alt–F7.
To standardize the keyboard mapping of programs, changes were made to the following files:
/etc/inputrc /etc/X11/Xmodmap /etc/skel/.emacs /etc/skel/.gnu-emacs /etc/skel/.vimrc /etc/csh.cshrc /etc/termcap /usr/share/terminfo/x/xterm /usr/share/X11/app-defaults/XTerm /usr/share/emacs/VERSION/site-lisp/term/*.el
These changes only affect applications that use terminfo
entries or whose configuration files are changed directly
(vi
, emacs
, etc.). Applications not
shipped with the system should be adapted to these defaults.
Under X, the compose key (multikey) can be enabled as explained in
/etc/X11/Xmodmap
.
Further settings are possible using the X Keyboard Extension (XKB).
Information about XKB is available in the documents listed in
/usr/share/doc/packages/xkeyboard-config
(part of the
xkeyboard-config
package).
The system is, to a very large extent, internationalized and can be modified for local needs. Internationalization (I18N) allows specific localization (L10N). The abbreviations I18N and L10N are derived from the first and last letters of the words and, in between, the number of letters omitted.
Settings are made with LC_
variables defined in the
file /etc/sysconfig/language
. This refers not only to
native language support, but also to the categories
Messages (Language), Character Set,
Sort Order, Time and Date,
Numbers and Money. Each of these
categories can be defined directly with its own variable or indirectly with a
master variable in the file language
(see the
locale
man page).
RC_LC_MESSAGES
,
RC_LC_CTYPE
,
RC_LC_COLLATE
,
RC_LC_TIME
,
RC_LC_NUMERIC
,
RC_LC_MONETARY
These variables are passed to the shell without the
RC_
prefix and represent the listed categories.
The shell profiles concerned are listed below. The current setting can be
shown with the command locale
.
RC_LC_ALL
This variable, if set, overwrites the values of the variables already mentioned.
RC_LANG
If none of the previous variables are set, this is the fallback. By
default, only RC_LANG
is set. This makes it
easier for users to enter their own values.
ROOT_USES_LANG
This variable can be set to yes
or
ctype
(default). If set to
yes
, root
uses language and country-specific settings, otherwise the system administrator
always works in a POSIX environment.
The variables can be set with the YaST sysconfig editor. The value of such a variable contains the language code, country code, encoding and modifier. The individual components are joined by special characters:
LANG=<language>[[_<COUNTRY>].<Encoding>[@<Modifier>]]
systemd
reads /etc/locale.conf
at early boot. The locale settings configured in this file are
inherited by every service or user, unless there are individual
settings.
Earlier versions of SUSE Linux Enterprise Desktop read locale settings from
/etc/sysconfig/language
,
/etc/sysconfig/keyboard
, and
/etc/sysconfig/console
.
Starting with SUSE Linux Enterprise Desktop
15 GA,
these files are considered obsolete.
systemd
does not read settings from these files anymore.
Instead, systemd
reads /etc/locale.conf
.
However, variables defined in /etc/sysconfig/language
will still be used: They override the system-wide locale and can be used to
define different locale settings for user shells (see Section 25.4.2, “Some Examples”).
To set the system-wide locale, you can either:
Write your settings in /etc/locale.conf
.
Each line is a environment-like variable assignment (see
man 5 locale.conf
for a list of variables):
LANG=de_DE.UTF-8
To fine-tune the settings, you can add additional variables, one variable per line.
Use the command localectl
:
root #
localectl
set-locale LANG=de_DE.UTF-8
Same here, you can also specify additional variables after the
localectl set-locale
command.
To keep backward compatibility with old systems during the update of the systemd package, all variables mentioned will be migrated from sysconfig to their final destinations if they are not already defined there.
You should always set the language and country codes together. Language settings follow the standard ISO 639 available at http://www.evertype.com/standards/iso639/iso639-en.html and http://www.loc.gov/standards/iso639-2/. Country codes are listed in ISO 3166, see http://en.wikipedia.org/wiki/ISO_3166.
It only makes sense to set values for which usable description files can be
found in /usr/lib/locale
. Additional description files
can be created from the files in /usr/share/i18n
using
the command localedef
. The description files are part of
the glibc-i18ndata
package. A description file for
en_US.UTF-8
(for English and United States) can be
created with:
localedef -i en_US -f UTF-8 en_US.UTF-8
LANG=en_US.UTF-8
This is the default setting if American English is selected during installation. If you selected another language, that language is enabled but still with UTF-8 as the character encoding.
LANG=en_US.ISO-8859-1
This sets the language to English, country to United States and the
character set to ISO-8859-1
. This character set does
not support the Euro sign, but it can be useful sometimes for programs
that have not been updated to support UTF-8
. The
string defining the charset (ISO-8859-1
in this case)
is then evaluated by programs like Emacs.
LANG=en_IE@euro
The above example explicitly includes the Euro sign in a language setting. This setting is obsolete now, as UTF-8 also covers the Euro symbol. It is only useful if an application supports ISO-8859-15 and not UTF-8.
Changes to /etc/sysconfig/language
are activated by the
following process chain:
For the Bash: /etc/profile
reads
/etc/profile.d/lang.sh
which, in turn, analyzes
/etc/sysconfig/language
.
For tcsh: At login, /etc/csh.login
reads
/etc/profile.d/lang.csh
which, in turn, analyzes
/etc/sysconfig/language
.
This ensures that any changes to
/etc/sysconfig/language
are available at the next login
to the respective shell, without having to manually activate
them.
Users can override the system defaults by editing their
~/.bashrc
accordingly. For example, if you do not want
to use the system-wide en_US
for program messages,
include LC_MESSAGES=es_ES
so that messages are
displayed in Spanish instead.
~/.i18n
#Edit source
If you are not satisfied with locale system defaults, change the settings in
~/.i18n
according to the Bash scripting syntax. Entries
in ~/.i18n
override system defaults from
/etc/sysconfig/language
. Use the same variable names
but without the RC_
namespace prefixes. For example, use
LANG
instead of RC_LANG
:
LANG=cs_CZ.UTF-8 LC_COLLATE=C
Files in the category Messages are, as a rule, only
stored in the corresponding language directory (like
en
) to have a fallback. If you set
LANG
to en_US
and the message
file in /usr/share/locale/en_US/LC_MESSAGES
does not
exist, it falls back to
/usr/share/locale/en/LC_MESSAGES
.
A fallback chain can also be defined, for example, for Breton to French or for Galician to Spanish to Portuguese:
LANGUAGE="br_FR:fr_FR"
LANGUAGE="gl_ES:es_ES:pt_PT"
If desired, use the Norwegian variants Nynorsk and Bokmål instead (with
additional fallback to no
):
LANG="nn_NO"
LANGUAGE="nn_NO:nb_NO:no"
or
LANG="nb_NO"
LANGUAGE="nb_NO:nn_NO:no"
Note that in Norwegian, LC_TIME
is also treated
differently.
One problem that can arise is a separator used to delimit groups of digits
not being recognized properly. This occurs if LANG
is set to only a two-letter language code like de
, but
the definition file glibc uses is located in
/usr/share/lib/de_DE/LC_NUMERIC
. Thus
LC_NUMERIC
must be set to de_DE
to make the separator definition visible to the system.
The GNU C Library Reference Manual, Chapter “Locales and Internationalization”. It is included in the package glibc-info.
Markus Kuhn, UTF-8 and Unicode FAQ for Unix/Linux, currently at https://www.cl.cam.ac.uk/~mgk25/unicode.html.
NetworkManager is the ideal solution for laptops and other portable computers. It supports state-of-the-art encryption types and standards for network connections, including connections to 802.1X protected networks. 802.1X is the “IEEE Standard for Local and Metropolitan Area Networks—Port-Based Network Access Control”. With NetworkManager, you need not worry about configuring network interfaces and switching between wired or wireless networks when you are on the move. NetworkManager can automatically connect to known wireless networks or manage several network connections in parallel—the fastest connection is then used as default. Furthermore, you can manually switch between available networks and manage your network connection using an applet in the system tray.
Instead of only one connection being active, multiple connections may be active at once. This enables you to unplug your laptop from an Ethernet and remain connected via a wireless connection.
NetworkManager is only supported by SUSE for desktop workloads with SLED or Workstation extension. All server certifications are done with wicked as the network configuration tool, and using NetworkManager may invalidate them. NetworkManager is not supported by SUSE for server workloads.
NetworkManager provides a sophisticated and intuitive user interface, which enables users to easily switch their network environment. However, NetworkManager is not a suitable solution in the following cases:
Your computer provides network services for other computers in your network, for example, it is a DHCP or DNS server.
Your computer is a Xen server or your system is a virtual system inside Xen.
On desktop and laptop computers, NetworkManager is enabled by default. You can disable and enable it at any time using the Network Settings module in YaST.
Run YaST and go to
› .The
dialog opens. Go to the tab.To configure and manage your network connections with NetworkManager:
In the
field, select .Click
and close YaST.Configure your network connections with NetworkManager as described in Section 26.3, “Configuring Network Connections”.
To deactivate NetworkManager and control the network with your own configuration:
In the
field, choose .Click
.Set up your network card with YaST using automatic configuration via DHCP or a static IP address.
Find a detailed description of the network configuration with YaST in Section 19.4, “Configuring a Network Connection with YaST”.
After enabling NetworkManager in YaST, configure your network connections with the NetworkManager front-end available in GNOME. It shows tabs for all types of network connections, such as wired, wireless, mobile broadband, DSL, and VPN connections.
To open the network configuration dialog in GNOME, open the settings menu via the status menu and click the
entry.
Depending on your system setup, you may not be allowed to configure
connections. In a secured environment, some options may be locked or
require root
permission. Ask your system administrator for details.
Open the NetworkManager configuration dialog.
To add a Connection:
Click the
icon in the lower left corner.Select your preferred connection type and follow the instructions.
When you are finished click
.After confirming your changes, the newly-configured network connection appears in the list of available networks in the Status Menu.
To edit a connection:
Select the entry to edit.
Click the gear icon to open the
dialog.Insert your changes and click
to save them.To make your connection available as a system connection go to the Section 26.4.1, “User and System Connections”.
tab and set the check box . For more information about user and system connections, seeIf your computer is connected to a wired network, use the NetworkManager applet to manage the connection.
Open the Status Menu and click
to change the connection details or to switch it off.To change the settings click
and then click the gear icon.To switch off all network connections, activate the
setting.Visible wireless networks are listed in the GNOME NetworkManager applet menu under
. The signal strength of each network is also shown in the menu. Encrypted wireless networks are marked with a shield icon.To connect to a visible wireless network, open the Status Menu and click
.Click
to enable it.Click
, select your Wi-Fi Network and click .If the network is encrypted, a configuration dialog opens. It shows the type of encryption the network uses and text boxes for entering the login credentials.
To connect to a network that does not broadcast its service set identifier (SSID or ESSID) and therefore cannot be detected automatically, open the Status Menu and click
.Click
to open the detailed settings menu.Make sure your Wi-Fi is enabled and click
.In the dialog that opens, enter the SSID or ESSID in
and set encryption parameters if necessary.A wireless network that has been chosen explicitly will remain connected as long as possible. If a network cable is plugged in during that time, any connections that have been set to
will be connected, while the wireless connection remains up.On the initial connection, many public wireless hotspots force users to visit a landing page (the captive portal). Before you have logged in or agreed to the terms and conditions, all your HTTP requests are redirected to the provider's captive portal.
When connecting to a wireless network with a captive portal, NetworkManager and GNOME will automatically show the login page as part of the connection process. This ensures that you always know when you are connected, and helps you to get set up as quickly as possible without using the browser to login.
To enable this feature, install the package NetworkManager-branding-SLE and restart NetworkManager with:
tux >
sudo
systemctl restart network
Whenever you connect to a network with a captive portal, NetworkManager (or GNOME) will open the captive portal login page for you. Login with your credentials to get access to the Internet.
If your Wi-Fi/Bluetooth card supports access point mode, you can use NetworkManager for the configuration.
Open the Status Menu and click
.Click
to open the detailed settings menu.Click
and follow the instructions.Use the credentials shown in the resulting dialog to connect to the hotspot from a remote machine.
NetworkManager supports several Virtual Private Network (VPN) technologies. For each technology, SUSE Linux Enterprise Desktop comes with a base package providing the generic support for NetworkManager. In addition to that, you also need to install the respective desktop-specific package for your applet.
To use this VPN technology, install:
NetworkManager-openvpn
NetworkManager-openvpn-gnome
To use this VPN technology, install:
NetworkManager-openconnect
NetworkManager-openconnect-gnome
To use this VPN technology, install:
NetworkManager-pptp
NetworkManager-pptp-gnome
The following procedure describes how to set up your computer as an OpenVPN client using NetworkManager. Setting up other types of VPNs works analogously.
Before you begin, make sure that the package
NetworkManager-openvpn-gnome
is
installed and all dependencies have been resolved.
Open the application
by clicking the status icons at the right end of the panel and clicking the icon. In the window , choose .Click the
icon.Select
and then .Choose the
type. Depending on the setup of your OpenVPN server, choose or .Insert the necessary values into the respective text boxes. For our example configuration, these are:
|
The remote endpoint of the VPN server |
|
The user (only available when you have selected ) |
|
The password for the user (only available when you have selected ) |
|
|
|
|
|
|
Finish the configuration with
.To enable the connection, in the
panel of the application click the switch button. Alternatively, click the status icons at the right end of the panel, click the name of your VPN and then .NetworkManager distinguishes two types of wireless connections: trusted and untrusted. A trusted connection is any network that you explicitly selected in the past. All others are untrusted. Trusted connections are identified by the name and MAC address of the access point. Using the MAC address ensures that you cannot use a different access point with the name of your trusted connection.
NetworkManager periodically scans for available wireless networks. If multiple trusted networks are found, the most recently used is automatically selected. NetworkManager waits for your selection in case if all networks are untrusted.
If the encryption setting changes but the name and MAC address remain the same, NetworkManager attempts to connect, but first you are asked to confirm the new encryption settings and provide any updates, such as a new key.
If you switch from using a wireless connection to offline mode, NetworkManager blanks the SSID or ESSID. This ensures that the card is disconnected.
NetworkManager knows two types of connections: user
and
system
connections.
User connections require every user to authenticate in NetworkManager, which stores the user's credentials in their local GNOME keyring so they don't have to re-enter them every time they connect.
System connections are available to all users automatically. The first user to create the connection enters any necessary credentials, and then all other users have access without needing to know the credentials. The difference in configuring a user or system connection is a single checkbox, Section 26.3, “Configuring Network Connections”.
. For information on how to configure user or system connections with NetworkManager, refer toIf you do not want to re-enter your credentials each time you want to connect to an encrypted network, you can use the GNOME Keyring Manager to store your credentials encrypted on the disk, secured by a master password.
firewalld
Zones in NetworkManager #The firewall zones set general rules about which network connections are allowed. To configure the zone of firewalld for a wired connection, go to the Identity tab of the connection settings. To configure the zone of firewalld for a WiFi connection, go to the Security tab of the connection settings.
If you are in your home network, use the zone
home
. For public wireless networks, switch to
public
. If you are in a secure environment and
want to allow all connections, use the zone
trusted
.
For details about firewalld, see Book “Security and Hardening Guide”, Chapter 23 “Masquerading and Firewalls”, Section 23.4 “firewalld
”.
In the following, find some frequently asked questions about configuring special network options with NetworkManager.
By default, connections in NetworkManager are device type-specific: they apply to all physical devices with the same type. If more than one physical device per connection type is available (for example, your machine is equipped with two Ethernet cards), you can tie a connection to a certain device.
To do this in GNOME, first look up the MAC address of your device (use
the nm-tool
or wicked show all
). Then start the dialog for
configuring network connections and choose the connection you want to
modify. On the or
tab, enter the of the device and confirm
your changes.
When multiple access points with different wireless bands (a/b/g/n) are available, the access point with the strongest signal is automatically chosen by default. To override this, use the
field when configuring wireless connections.The Basic Service Set Identifier (BSSID) uniquely identifies each Basic Service Set. In an infrastructure Basic Service Set, the BSSID is the MAC address of the wireless access point. In an independent (ad-hoc) Basic Service Set, the BSSID is a locally administered MAC address generated from a 46-bit random number.
Start the dialog for configuring network connections as described in Section 26.3, “Configuring Network Connections”. Choose the wireless connection you want to modify and click . On the tab, enter the BSSID.
The primary device (the device which is connected to the Internet) does not need any special configuration. However, you need to configure the device that is connected to the local hub or machine as follows:
Start the dialog for configuring network connections as described in Section 26.3, “Configuring Network Connections”. Choose the connection you want to modify and click . Switch to the tab and from the drop-down box, activate . That will enable IP traffic forwarding and run a DHCP server on the device. Confirm your changes in NetworkManager.
As the DCHP server uses port 67
, make sure that it
is not blocked by the firewall: On the machine sharing the connections,
start YaST and select › . Switch to
the category. If is not already shown as , select from
and click .
Confirm your changes in YaST.
In case a DHCP server provides invalid DNS information (and/or routes), you can override it. Start the dialog for configuring network connections as described in Section 26.3, “Configuring Network Connections”. Choose the connection you want to modify and click . Switch to the tab, and from the drop-down box, activate . Enter the DNS information in the and fields. To click and activate the respective check box. Confirm your changes.
Define a system connection
that can be used for such
purposes. For more information, refer to
Section 26.4.1, “User and System Connections”.
Connection problems can occur. Some common problems related to NetworkManager include the applet not starting or a missing VPN option. Methods for resolving and preventing these problems depend on the tool used.
The applets starts automatically if the network is set up for NetworkManager control. If the applet does not start, check if NetworkManager is enabled in YaST as described in Section 26.2, “Enabling or Disabling NetworkManager”. Then make sure that the NetworkManager-gnome package is also installed.
If the desktop applet is installed but is not running for some reason,
start it manually with the command nm-applet
.
Support for NetworkManager, applets, and VPN for NetworkManager is distributed in separate packages. If your NetworkManager applet does not include the VPN option, check if the packages with NetworkManager support for your VPN technology are installed. For more information, see Section 26.3.5, “NetworkManager and VPN”.
If you have configured your network connection correctly and all other
components for the network connection (router, etc.) are also up and
running, it sometimes helps to restart the network interfaces on your
computer. To do so, log in to a command line as root
and run
systemctl restart wickeds
.
More information about NetworkManager can be found on the following Web sites and directories:
https://gitlab.freedesktop.org/NetworkManager/NetworkManager
Also check out the information in the following directories for the latest information about NetworkManager and the GNOME applet:
/usr/share/doc/packages/NetworkManager/
,
/usr/share/doc/packages/NetworkManager-gnome/
.
Power management is especially important on laptop computers, but is also useful on other systems. ACPI (Advanced Configuration and Power Interface) is available on all modern computers (laptops, desktops, and servers). Power management technologies require suitable hardware and BIOS routines. Most laptops and many modern desktops and servers meet these requirements. It is also possible to control CPU frequency scaling to save power or decrease noise.
Power saving functions are not only significant for the mobile use of laptops, but also for desktop systems. The main functions and their use in ACPI are:
Not supported.
This mode writes the entire system state to the RAM. Subsequently, the
entire system except the RAM is put to sleep. In this state, the computer
consumes very little power. The advantage of this state is the
possibility of resuming work at the same point within a few seconds
without having to boot and restart applications. This function
corresponds to the ACPI state S3
.
In this operating mode, the entire system state is written to the hard
disk and the system is powered off. There must be a swap partition at
least as big as the RAM to write all the active data. Reactivation from
this state takes about 30 to 90 seconds. The state prior to the suspend
is restored. Some manufacturers offer useful hybrid variants of this
mode, such as RediSafe in IBM Thinkpads. The corresponding ACPI state is
S4
. In Linux, suspend to disk is performed by kernel
routines that are independent from ACPI.
mkswap
Do not reformat existing swap partitions with mkswap
if possible. Reformatting with mkswap
will change
the UUID value of the swap partition. Either reformat via YaST (which
will update /etc/fstab
) or adjust
/etc/fstab
manually.
ACPI checks the battery charge status and provides information about it. Additionally, it coordinates actions to perform when a critical charge status is reached.
Following a shutdown, the computer is powered off. This is especially important when an automatic shutdown is performed shortly before the battery is empty.
In connection with the CPU, energy can be saved in three different ways: frequency and voltage scaling (also known as PowerNow! or Speedstep), throttling and putting the processor to sleep (C-states). Depending on the operating mode of the computer, these methods can also be combined.
ACPI was designed to enable the operating system to set up and control the individual hardware components. ACPI supersedes both Power Management Plug and Play (PnP) and Advanced Power Management (APM). It delivers information about the battery, AC adapter, temperature, fan and system events, like “close lid” or “battery low.”
The BIOS provides tables containing information about the individual
components and hardware access methods. The operating system uses this
information for tasks like assigning interrupts or activating and
deactivating components. Because the operating system executes commands
stored into the BIOS, the functionality depends on the BIOS implementation.
The tables ACPI can detect and load are reported in journald. See
Chapter 17, journalctl
: Query the systemd
Journal for more information on viewing the journal
log messages. See Section 27.2.2, “Troubleshooting” for more information
about troubleshooting ACPI problems.
The CPU can save energy in three ways:
Frequency and Voltage Scaling
Throttling the Clock Frequency (T-states)
Putting the Processor to Sleep (C-states)
Depending on the operating mode of the computer, these methods can be combined. Saving energy also means that the system heats up less and the fans are activated less frequently.
Frequency scaling and throttling are only relevant if the processor is busy, because the most economic C-state is applied anyway when the processor is idle. If the CPU is busy, frequency scaling is the recommended power saving method. Often the processor only works with a partial load. In this case, it can be run with a lower frequency. Usually, dynamic frequency scaling controlled by the kernel on-demand governor is the best approach.
Throttling should be used as the last resort, for example, to extend the battery operation time despite a high system load. However, some systems do not run smoothly when they are throttled too much. Moreover, CPU throttling does not make sense if the CPU has little to do.
For in-depth information, refer to Book “System Analysis and Tuning Guide”, Chapter 11 “Power Management”.
There are two different types of problems. On one hand, the ACPI code of the kernel may contain bugs that were not detected in time. In this case, a solution will be made available for download. More often, the problems are caused by the BIOS. Sometimes, deviations from the ACPI specification are purposely integrated in the BIOS to circumvent errors in the ACPI implementation of other widespread operating systems. Hardware components that have serious errors in the ACPI implementation are recorded in a blacklist that prevents the Linux kernel from using ACPI for these components.
The first thing to do when problems are encountered is to update the BIOS. If the computer does not boot, one of the following boot parameters may be helpful:
Do not use ACPI for configuring the PCI devices.
Only perform a simple resource configuration. Do not use ACPI for other purposes.
Disable ACPI.
Some newer machines (especially SMP systems and AMD64 systems) need ACPI for configuring the hardware correctly. On these machines, disabling ACPI can cause problems.
Sometimes, the machine is confused by hardware that is attached over USB or FireWire. If a machine refuses to boot, unplug all unneeded hardware and try again.
Monitor the boot messages of the system with the command dmesg
-T
| grep -2i acpi
(or all messages, because the
problem may not be caused by ACPI) after booting. If an error occurs while
parsing an ACPI table, the most important table—the DSDT
(Differentiated System Description Table)—can be
replaced with an improved version. In this case, the faulty DSDT of the
BIOS is ignored. The procedure is described in
Section 27.4, “Troubleshooting”.
In the kernel configuration, there is a switch for activating ACPI debug messages. If a kernel with ACPI debugging is compiled and installed, detailed information is issued.
If you experience BIOS or hardware problems, it is always advisable to contact the manufacturers. Especially if they do not always provide assistance for Linux, they should be confronted with the problems. Manufacturers will only take the issue seriously if they realize that an adequate number of their customers use Linux.
https://tldp.org/HOWTO/ACPI-HOWTO/ (detailed ACPI HOWTO, contains DSDT patches)
https://uefi.org/specifications (Advanced Configuration & Power Interface Specification)
https://01.org/linux-acpi (the Linux ACPI project)
In Linux, the hard disk can be put to sleep entirely if it is not needed or
it can be run in a more economic or quieter mode. On modern laptops, you do
not need to switch off the hard disks manually, because they automatically
enter an economic operating mode whenever they are not needed. However, if
you want to maximize power savings, test some of the following methods,
using the hdparm
command.
It can be used to modify various hard disk settings. The option
-y
instantly switches the hard disk to the standby mode.
-Y
puts it to sleep. hdparm
-S
X causes the hard disk to be
spun down after a certain period of inactivity. Replace
X as follows: 0
disables this
mechanism, causing the hard disk to run continuously. Values from
1
to 240
are multiplied by 5
seconds. Values from 241
to 251
correspond to 1 to 11 times 30 minutes.
Internal power saving options of the hard disk can be controlled with the
option -B
. Select a value from 0
to
255
for maximum saving to maximum throughput. The result
depends on the hard disk used and is difficult to assess. To make a hard
disk quieter, use the option -M
. Select a value from
128
to 254
for quiet to fast.
Often, it is not so easy to put the hard disk to sleep. In Linux, numerous
processes write to the hard disk, waking it up repeatedly. Therefore, it is
important to understand how Linux handles data that needs to be written to
the hard disk. First, all data is buffered in the RAM. This buffer is
monitored by the pdflush
daemon.
When the data reaches a certain age limit or when the buffer is filled to a
certain degree, the buffer content is flushed to the hard disk. The buffer
size is dynamic and depends on the size of the memory and the system load.
By default, pdflush is set to short intervals to achieve maximum data
integrity. It checks the buffer every 5 seconds and writes the data to the
hard disk. The following variables are interesting:
/proc/sys/vm/dirty_writeback_centisecs
Contains the delay until a pdflush thread wakes up (in hundredths of a second).
/proc/sys/vm/dirty_expire_centisecs
Defines after which timeframe a dirty page should be written at latest.
Default is 3000
, which means 30 seconds.
/proc/sys/vm/dirty_background_ratio
Maximum percentage of dirty pages until pdflush begins to write them.
Default is 5
%.
/proc/sys/vm/dirty_ratio
When the dirty pages exceed this percentage of the total memory, processes are forced to write dirty buffers during their time slice instead of continuing to write.
Changes to the pdflush
daemon
settings endanger the data integrity.
Apart from these processes, journaling file systems, like
Btrfs
,
Ext3
,
Ext4
and others write their
metadata independently from pdflush
,
which also prevents the hard disk from spinning down.
To avoid this, a special kernel extension has been
developed for mobile devices. To use the extension, install the
laptop-mode-tools
package and
see
/usr/src/linux/Documentation/laptops/laptop-mode.txt
for details.
Another important factor is the way active programs behave. For example, good editors regularly write hidden backups of the currently modified file to the hard disk, causing the disk to wake up. Features like this can be disabled at the expense of data integrity.
In this connection, the mail daemon postfix uses the variable
POSTFIX_LAPTOP
. If this variable is set to
yes
, postfix accesses the hard disk far less frequently.
In SUSE Linux Enterprise Desktop these technologies are controlled by
laptop-mode-tools
.
All error messages and alerts are logged in the system journal, which can be
queried with the command journalctl
(see
Chapter 17, journalctl
: Query the systemd
Journal for more information). The following
sections cover the most common problems.
Refer to the kernel sources to see if your processor is supported. You may
need a special kernel module or module option to activate CPU frequency
control. If the kernel-source
package is installed, this information is available in
/usr/src/linux/Documentation/cpu-freq/*
.
This chapter contains additional information on when SUSE Linux Enterprise Desktop is used in a virtual machine.
Some virtualization environments allow adding or removing CPUs while the virtual machine is running.
For safe removal of CPUs, first deactivate them by executing
root #
echo 0 > /sys/devices/system/cpu/cpuX/online
Replace X with the CPU number. To bring a CPU back online, execute
root #
echo 1 > /sys/devices/system/cpu/cpuX/online
This chapter contains additional information about using SUSE Linux Enterprise with non-volatile main memory, also known as Persistent Memory, comprising one or more NVDIMMs.
Persistent memory is a new type of computer storage, combining speeds approaching those of dynamic RAM (DRAM) along with RAM's byte-by-byte addressability, plus the permanence of solid-state disks (SSDs).
SUSE currently supports the use of persistent memory with SUSE Linux Enterprise Server on machines with the AMD64/Intel 64 and POWER architectures.
Like conventional RAM, persistent memory is installed directly into motherboard memory slots. As such, it is supplied in the same physical form factor as RAM—as DIMMs. These are known as NVDIMMs: non-volatile dual inline memory modules.
Unlike RAM, though, persistent memory is also similar to flash-based SSDs in several ways. Both are based on forms of solid-state memory circuitry, but despite this, both provide non-volatile storage: Their contents are retained when the system is powered off or restarted. For both forms of medium, writing data is slower than reading it, and both support a limited number of rewrite cycles. Finally, also like SSDs, sector-level access to persistent memory is possible if that is more suitable for a particular application.
Different models use different forms of electronic storage medium, such as Intel 3D XPoint, or a combination of NAND-flash and DRAM. New forms of non-volatile RAM are also in development. This means that different vendors and models of NVDIMM offer different performance and durability characteristics.
Because the storage technologies involved are in an early stage of development, different vendors' hardware may impose different limitations. Thus, the following statements are generalizations.
Persistent memory is up to ten times slower than DRAM, but around a thousand times faster than flash storage. It can be rewritten on a byte-by-byte basis rather than flash memory's whole-sector erase-and-rewrite process. Finally, while rewrite cycles are limited, most forms of persistent memory can handle millions of rewrites, compared to the thousands of cycles of flash storage.
This has two important consequences:
It is not possible with current technology to run a system with only persistent memory and thus achieve completely non-volatile main memory. You must use a mixture of both conventional RAM and NVDIMMs. The operating system and applications will execute in conventional RAM, with the NVDIMMs providing very fast supplementary storage.
The performance characteristics of different vendors' persistent memory mean that it may be necessary for programmers to be aware of the hardware specifications of the NVDIMMs in a particular server, including how many NVDIMMs there are and in which memory slots they are fitted. This will obviously impact hypervisor use, migration of software between different host machines, and so on.
This new storage subsystem is defined in version 6 of the ACPI standard.
However, libnvdimm
supports pre-standard NVDIMMs and
they can be used in the same way.
A region is a block of persistent memory that can be divided up into one or more namespaces. You cannot access the persistent memory of a region without first allocating it to a namespace.
A single contiguously-addressed range of non-volatile storage, comparable
to NVM Express SSD namespaces, or to SCSI Logical Units (LUNs). Namespaces
appear in the server's /dev
directory as separate
block devices. Depending on the method of access required, namespaces can
either amalgamate storage from multiple NVDIMMs into larger volumes, or
allow it to be partitioned into smaller volumes.
Each namespace also has a mode that defines which NVDIMM features are enabled for that namespace. Sibling namespaces of the same parent region will always have the same type, but might be configured to have different modes. Namespace modes include:
Device-DAX mode. Creates a single-character device file (
/dev/daxX.Y
). Does not require file system
creation.
File system-DAX mode. Default if no other mode is specified. Creates a
block device (/dev/pmemX
[.Y]
) which supports DAX for
ext4
or XFS
.
For legacy file systems which do not checksum metadata. Suitable for small boot volumes. Compatible with other operating systems.
A memory disk without a label or metadata. Does not support DAX. Compatible with other operating systems.
raw
mode is not supported by SUSE. It is not
possible to mount file systems on raw
namespaces.
Each namespace and region has a type that defines the way in which the persistent memory associated with that namespace or region can be accessed. A namespace always has the same type as its parent region. There are two different types: Persistent Memory, which can be configured in two different ways, and the deprecated Block Mode.
PMEM storage offers byte-level access, just like RAM. Using PMEM, a single namespace can include multiple interleaved NVDIMMs, allowing them all to be used as a single device.
There are two ways to configure a PMEM namespace.
A PMEM namespace configured for Direct Access (DAX) means that accessing the memory bypasses the kernel's page cache and goes direct to the medium. Software can directly read or write every byte of the namespace separately.
A PMEM namespace configured to operate in BTT mode is accessed on a sector-by-sector basis, like a conventional disk drive, rather than the more RAM-like byte-addressable model. A translation table mechanism batches accesses into sector-sized units.
The advantage of BTT is data protection: the storage subsystem ensures that each sector is completely written to the underlying medium, and if a write fails for some reason, it will be unrolled. Thus a given sector cannot be partially written.
Additionally, access to BTT namespaces is cached by the kernel.
The drawback is that DAX is not possible for BTT namespaces.
Block mode storage addresses each NVDIMM as a separate device. Its use is deprecated and no longer supported.
Apart from devdax
namespaces, all other types must be
formatted with a file system, just as with a conventional drive.
SUSE Linux Enterprise Desktop supports the ext2
,
ext4
and XFS
file systems for this.
DAX allows persistent memory to be directly mapped into a process's
address space, for example using the mmap
system call.
A memory address as an offset into a single DIMM's memory; that is, starting from zero as the lowest addressable byte on that DIMM.
Metadata stored on the NVDIMM, such as namespace definitions. This can be accessed using DSMs.
ACPI method to access the firmware on an NVDIMM.
It is important to note that this form of memory access is not transactional. In the event of a power outage or other system failure, data may not be completely written into storage. PMEM storage is only suitable if the application can handle the situation of partially-written data.
If the server will host an application that can directly use large amounts
of fast storage on a byte-by-byte basis, the programmer can use the mmap
system call to place blocks of persistent memory directly into the
application's address space, without using any additional system RAM.
Avoid using the kernel page cache if you wish to conserve the use of RAM for the page cache, and instead give it to your applications. For instance, non-volatile memory could be dedicated to holding virtual machine (VM) images. As these would not be cached, this would reduce the cache usage on the host, allowing more VMs per host.
This is useful when you want to use the persistent memory on a set of NVDIMMs as a disk-like pool of very fast storage. For example, placing the filesystem journal on PMEM with BTT increase the reliability of filesystem recovery after a power failure or other sudden interruption (see Section 29.5.3, “Creating a PMEM Namespace with BTT”).
To applications, such devices just appear as very fast SSDs and can be used like any other storage device. For example, LVM can be layered on top of the persistent memory and will work as normal.
The advantage of BTT is that sector write atomicity is guaranteed, so even sophisticated applications that depend on data integrity will keep working. Media error reporting works through standard error-reporting channels.
To manage persistent memory, it is necessary to install the
ndctl
package. This also installs the
libndctl
package, which provides a set of user-space
libraries to configure NVDIMMs.
These tools work via the libnvdimm
library, which
supports three types of NVDIMM:
PMEM
BLK
Simultaneous PMEM and BLK
The ndctl
utility has a helpful set of
man
pages, accessible with the command:
tux >
ndctl help subcommand
To see a list of available subcommands, use:
tux >
ndctl --list-cmds
The available subcommands include:
Displays the current version of the NVDIMM support tools.
Makes the specified namespace available for use.
Prevents the specified namespace from being used.
Creates a new namespace from the specified storage devices.
Removes the specified namespace.
Makes the specified region available for use.
Prevents the specified region from being used.
Erases the metadata from a device.
Retrieves the metadata of the specified device.
Displays available devices.
Displays information about using the tool.
The ndctl
list
command can be used to
list all available NVDIMMs in a system.
In the following example, the system has three NVDIMMs, which are in a single, triple-channel interleaved set.
root #
ndctl list --dimms
[ { "dev":"nmem2", "id":"8089-00-0000-12325476" }, { "dev":"nmem1", "id":"8089-00-0000-11325476" }, { "dev":"nmem0", "id":"8089-00-0000-10325476" } ]
With a different parameter, ndctl
list
will also list the available regions.
Regions may not appear in numerical order.
Note that although there are only three NVDIMMs, they appear as four regions.
root #
ndctl list --regions
[ { "dev":"region1", "size":68182605824, "available_size":68182605824, "type":"blk" }, { "dev":"region3", "size":202937204736, "available_size":202937204736, "type":"pmem", "iset_id":5903239628671731251 }, { "dev":"region0", "size":68182605824, "available_size":68182605824, "type":"blk" }, { "dev":"region2", "size":68182605824, "available_size":68182605824, "type":"blk" } ]
The space is available in two different forms: either as three separate 64 GB regions of type BLK, or as one combined 189 GB region of type PMEM which presents all the space on the three interleaved NVDIMMs as a single volume.
Note that the displayed value for available_size
is the
same as that for size
. This means that none of the space
has been allocated yet.
For the first example, we will configure our three NVDIMMs into a single PMEM namespace with Direct Access (DAX).
The first step is to create a new namespace.
root #
ndctl create-namespace --type=pmem --mode=fsdax --map=memory
{ "dev":"namespace3.0", "mode":"memory", "size":199764213760, "uuid":"dc8ebb84-c564-4248-9e8d-e18543c39b69", "blockdev":"pmem3" }
This creates a block device /dev/pmem3
, which supports
DAX. The 3
in the device name is inherited from the
parent region number, in this case region3
.
The --map=memory
option sets aside part of the PMEM
storage space on the NVDIMMs so that it can be used to allocate internal
kernel data structures called struct pages
. This allows
the new PMEM namespace to be used with features such as O_DIRECT
I/O
and RDMA
.
The reservation of some persistent memory for kernel data structures is why the resulting PMEM namespace has a smaller capacity than the parent PMEM region.
Next, we verify that the new block device is available to the operating system:
root #
fdisk -l /dev/pmem3
Disk /dev/pmem3: 186 GiB, 199764213760 bytes, 390164480 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Before it can be used, like any other drive, it must be formatted. In this example, we format it with XFS:
root #
mkfs.xfs /dev/pmem3
meta-data=/dev/pmem3 isize=256 agcount=4, agsize=12192640 blks = sectsz=4096 attr=2, projid32bit=1 = crc=0 finobt=0, sparse=0 data = bsize=4096 blocks=48770560, imaxpct=25 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 ftype=1 log =internal log bsize=4096 blocks=23813, version=2 = sectsz=4096 sunit=1 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0
Next, we can mount the new drive onto a directory:
root #
mount -o dax /dev/pmem3 /mnt/pmem3
Then we can verify that we now have a DAX-capable device:
root #
mount | grep dax
/dev/pmem3 on /mnt/pmem3 type xfs (rw,relatime,attr2,dax,inode64,noquota)
The result is that we now have a PMEM namespace formatted with the XFS file system and mounted with DAX.
Any mmap()
calls to files in that file system will
return virtual addresses that directly map to the persistent memory on our
NVDIMMs, completely bypassing the page cache.
Any fsync
or msync
calls on files in
that file system will still ensure that modified data has been fully
written to the NVDIMMs. These calls flush the processor cache lines
associated with any pages that have been modified in user space via
mmap
mappings.
Before creating any other type of volume that uses the same storage, we must unmount and then remove this PMEM volume.
First, unmount it:
root #
umount /mnt/pmem3
Then disable the namespace:
root #
ndctl disable-namespace namespace3.0
disabled 1 namespace
Then delete it:
root #
ndctl destroy-namespace namespace3.0
destroyed 1 namespace
BTT provides sector write atomicity, which makes it a good choice when you need data protection, for example for Ext4 and XFS journals. If there is a power failure, the journals are protected and should be recoverable. The following examples show how to create a PMEM namespace with BTT in sector mode, and how to place the filesystem journal in this namespace.
root #
ndctl create-namespace --type=pmem --mode=sector
{ "dev":"namespace3.0", "mode":"sector", "uuid":"51ab652d-7f20-44ea-b51d-5670454f8b9b", "sector_size":4096, "blockdev":"pmem3s" }
Next, verify that the new device is present:
root #
fdisk -l /dev/pmem3s
Disk /dev/pmem3s: 188.8 GiB, 202738135040 bytes, 49496615 sectors Units: sectors of 1 * 4096 = 4096 bytes Sector size (logical/physical): 4096 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Like the DAX-capable PMEM namespace we previously configured, this BTT-capable PMEM namespace consumes all the available storage on the NVDIMMs.
The trailing s
in the device name
(/dev/pmem3s
) stands for
sector
and can be used to easily distinguish namespaces
that are configured to use the BTT.
The volume can be formatted and mounted as in the previous example.
The PMEM namespace shown here cannot use DAX. Instead it uses the BTT to provide sector write atomicity. On each sector write through the PMEM block driver, the BTT will allocate a new sector to receive the new data. The BTT atomically updates its internal mapping structures after the new data is fully written so the newly written data will be available to applications. If the power fails at any point during this process, the write will be completely lost and the application will have access to its old data, still intact. This prevents the condition known as "torn sectors".
This BTT-enabled PMEM namespace can be formatted and used with a file system
just like any other standard block device. It cannot be used with DAX.
However, mmap
mappings for files on this block device
will use the page cache.
When you place the filesystem journal on a separate device, it must use the same filesystem block size as the filesystem. Most likely this is 4096, and you can find the block size with this command:
root #
blockdev --getbsz /dev/sda3
The following example creates a new Ext4 journal on a separate NVDIMM device, creates the filesystem on a SATA device, then attaches the new filesystem to the journal:
root #
mke2fs -b 4096 -O journal_dev /dev/pmem3s
root #
mkfs.ext4 -J device=/dev/pmem3s /dev/sda3
The following example creates a new XFS filesystem on a SATA drive, and creates the journal on a separate NVDIMM device:
root #
mkfs.xfs -l logdev=/dev/pmem3s /dev/sda3
See man 8 mkfs.ext4
and man 8 mkfs.ext4
for detailed information about options.
More about this topic can be found in the following list:
Contains instructions for configuring NVDIMM systems, information about testing, and links to specifications related to NVDIMM enabling. This site is developing as NVDIMM support in Linux is developing.
Information about configuring, using and programming systems with non-volatile memory under Linux and other operating systems. Covers the NVM Library (NVML), which aims to provide useful APIs for programming with persistent memory in user space.
LIBNVDIMM: Non-Volatile Devices
Aimed at kernel developers, this is part of the Documentation folder in
the current Linux kernel tree. It talks about the different kernel modules
involved in NVDIMM enablement, lays out some technical details of the
kernel implementation, and talks about the
sysfs
interface to the kernel that is used by the
ndctl
tool.
Utility library for managing the libnvdimm
subsystem
in the Linux kernel. Also contains user space libraries, as well as unit
tests and documentation.
YaST provides a service manager for controlling the default system target, services, displaying service status, and reading the log file. New in SUSE Linux Enterprise Desktop 15 SP1 is YaST support for Systemd socket-based services activation, which configures services to start on demand.
The NTP (network time protocol) mechanism is a protocol for synchronizing the system time over the network. First, a machine can obtain the time from a server that is a reliable time source. Second, a machine can itself act as a time source for other computers in the network. The goal is twofold—maintaining the absolute time and synchronizing the system time of all machines within a network.
The Network File System (NFS) is a protocol that allows access to files on a server in a manner similar to accessing local files.
SUSE Linux Enterprise Desktop installs NFS v4.2, which introduces support for sparse files, file pre-allocation, server-side clone and copy, application data block (ADB), and labeled NFS for mandatory access control (MAC) (requires MAC on both client and server).
Using Samba, a Unix machine can be configured as a file and print server for macOS, Windows, and OS/2 machines. Samba has developed into a fully-fledged and rather complex product. Configure Samba with YaST, or by editing the configuration file manually.
autofs
is a program that automatically mounts
specified directories on an on-demand basis. It is based on a kernel module
for high efficiency, and can manage both local directories and network
shares. These automatic mount points are mounted only when they are
accessed, and unmounted after a certain period of inactivity. This
on-demand behavior saves bandwidth and results in better performance than
static mounts managed by /etc/fstab
. While
autofs
is a control script,
automount
is the command (daemon) that does the actual
auto-mounting.
YaST provides a service manager for controlling the default system target, services, displaying service status, and reading the log file. New in SUSE Linux Enterprise Desktop 15 SP1 is YaST support for Systemd socket-based services activation, which configures services to start on demand.
Systemd supports starting services with socket-based activation, for starting
services on demand. These services have two unit types: service and socket.
For example, CUPS is controlled by cups.service
and
cups.socket
. YaST allows you to select the type of
service startup you want to use.
Figure 30.1, “YaST Service Manager” shows the options in the Start Mode drop-down menu: , , and . Select for socket-based activation. This opens a listening network socket, and the service starts when there is a request.
The man 5 systemd.socket
for detailed information on how
socket activation works.
The NTP (network time protocol) mechanism is a protocol for synchronizing the system time over the network. First, a machine can obtain the time from a server that is a reliable time source. Second, a machine can itself act as a time source for other computers in the network. The goal is twofold—maintaining the absolute time and synchronizing the system time of all machines within a network.
Maintaining an exact system time is important in many situations. The built-in hardware clock does often not meet the requirements of applications such as databases or clusters. Manual correction of the system time would lead to severe problems because, for example, a backward leap can cause malfunction of critical applications. Within a network, it is usually necessary to synchronize the system time of all machines, but manual time adjustment is a bad approach. NTP provides a mechanism to solve these problems. The NTP service continuously adjusts the system time with reliable time servers in the network. It further enables the management of local reference clocks, such as radio-controlled clocks.
Since SUSE Linux Enterprise Desktop 15, chrony
is the default implementation of NTP.
chrony
includes two parts; chronyd
is a daemon that can be started at
boot time and chronyc
is a command line interface program to monitor the
performance of chronyd
, and to change various operating parameters at
runtime.
To enable time synchronization by means of active directory, follow the instructions found at Book “Security and Hardening Guide”, Chapter 8 “Active Directory Support”, Section 8.3.3 “Joining Active Directory Using . ”, Joining an Active Directory Domain Using
The NTP daemon (chronyd
) coming with the chrony
package is preset to use the local computer hardware clock as a time
reference. The precision of a hardware clock heavily depends on its time
source. For example, an atomic clock or GPS receiver is a very precise time
source, while a common RTC chip is not a reliable time source. YaST
simplifies the configuration of an NTP client.
In the YaST NTP client configuration (
› ) window, you can specify when to start the NTP daemon, the type of the configuration source, and add custom time servers.You can choose from three options for when to start the NTP daemon:
Select chrony
daemon.
Select chrony
. You can set
the .
Select chronyd
automatically when the system is booted. This setting is recommended.
In the
drop-down box, select either or . Set if your server uses only a fixed set of (public) NTP servers, while is better if your internal network offers NTP servers via DHCP.Time servers for the client to query are listed in the lower part of the
window. Modify this list as needed with , , and .Click
to add a new time server:In the
field, type the URL of the time server or pool of time servers with which you want to synchronize the machine time. After the URL is complete, click to verify that it points to a valid time source.
Activate chronyd
daemon start.
Activate chronyd
daemon automatically and may not have an
Internet connection at boot time. This option is useful, for example, for
laptops with network connection managed by NetworkManager.
Confirm with
.
chrony
reads its configuration from the
/etc/chrony.conf
file. To keep the computer clock
synchronized, you need to tell chrony
what time servers to use. You can
use specific server names or IP addresses, for example:
server 0.europe.pool.ntp.org server 1.europe.pool.ntp.org server 2.europe.pool.ntp.org
You can also specify a pool name. Pool name resolves to several IP addresses:
pool pool.ntp.org
To synchronize time on multiple computers on the same network, we do not
recommend to synchronize all of them with an external server. A good
practice is to make one computer the time server which is synchronized with
an external time server, and the other computers act as its clients. Add a
local
directive to the server's
/etc/chrony.conf
to distinguish it from an
authoritative time server:
local stratum 10
To start chrony
, run:
systemctl start chronyd.service
After initializing chronyd
, it takes some time before the time is
stabilized and the drift file for correcting the local computer clock is
created. With the drift file, the systematic error of the hardware clock can
be computed when the computer is powered on. The correction is used
immediately, resulting in a higher stability of the system time.
To enable the service so that chrony
starts automatically at boot time,
run:
systemctl enable chronyd.service
chronyd
at Runtime Using chronyc
#Edit source
You can use chronyc
to change the behavior of chronyd
at runtime. It
also generates status reports about the operation of chronyd
.
You can run chronyc
either in interactive or non-interactive mode. To
run chronyc
interactively, enter chronyc
on the command line. It
displays a prompt and waits for your command input. For example, to check
how many NTP sources are online or offline, run:
root #
chronyc
chronyc> activity 200 OK 4 sources online 2 sources offline 1 sources doing burst (return to online) 1 sources doing burst (return to offline) 0 sources with unknown address
To exit chronyc
's prompt, enter quit
or
exit
.
If you do not need to use the interactive prompt, enter the command directly:
root #
chronyc
activity
Changes made using chronyc
are not permanent. They will be lost after the
next chronyd
restart. For permanent changes, modify
/etc/chrony.conf
.
For a complete list of chronyc
commands, see its manual page (man
1 chronyc
).
Although chronyd
starts up normally on a system that boots without a network
connection, the tool cannot resolve the DNS names of the time servers
specified in the configuration file.
chronyd
keeps trying to resolve the time server names specified by the
server
, pool
, and peer
directives in an increasing time interval until it succeeds.
If the time server will not be reachable when chronyd
is started, you can
specify the offline
option:
server server_address offline
chronyd
will then not try to poll the server until it is enabled using the
following command:
root #
chronyc online server_address
When the auto_offline
option is set, chronyd
assumes that
the time server has gone offline when two requests have been sent to it
without receiving a response. This option avoids the need to run the
'offline' command from chronyc
when disconnecting the network link.
The software package chrony
relies on other programs (such as
gpsd
) to access the timing data via the SHM or SOCK
driver. Use the refclock
directive in
/etc/chrony.conf
to specify a hardware reference clock
to be used as a time source. It has two mandatory parameters: a driver name
and a driver-specific parameter. The two parameters are followed by zero or
more refclock
options. chronyd
includes the following
drivers:
PPS - driver for the kernel 'pulse per second' API. For example:
refclock PPS /dev/pps0 lock NMEA refid GPS
SHM - NTP shared memory driver. For example:
refclock SHM 0 poll 3 refid GPS1 refclock SHM 1:perm=0644 refid GPS2
SOCK - Unix domain socket driver. For example:
refclock SOCK /var/run/chrony.ttyS0.sock
PHC - PTP hardware clock driver. For example:
refclock PHC /dev/ptp0 poll 0 dpoll -2 offset -37 refclock PHC /dev/ptp1:nocrossts poll 3 pps
For more information on individual drivers' options, see man 8
chrony.conf
.
Support for clock synchronization to an external time reference (ETR) is available. The external time reference sends an oscillator signal and a synchronization signal every 2**20 (2 to the power of 20) microseconds to keep TOD clocks of all connected servers synchronized.
For availability two ETR units can be connected to a machine. If the clock deviates for more than the sync-check tolerance all CPUs get a machine check that indicates that the clock is not synchronized. If this happens, all DASD I/O to XRC enabled devices is stopped until the clock is synchronized again.
The ETR support is activated via two sysfs
attributes;
run the following commands as root
:
echo 1 > /sys/devices/system/etr/etr0/online echo 1 > /sys/devices/system/etr/etr1/online
The Network File System (NFS) is a protocol that allows access to files on a server in a manner similar to accessing local files.
SUSE Linux Enterprise Desktop installs NFS v4.2, which introduces support for sparse files, file pre-allocation, server-side clone and copy, application data block (ADB), and labeled NFS for mandatory access control (MAC) (requires MAC on both client and server).
The Network File System (NFS) is a standardized, well-proven and widely supported network protocol that allows files to be shared between separate hosts.
The Network Information Service (NIS) can be used to have a centralized user management in the network. Combining NFS and NIS allows using file and directory permissions for access control in the network. NFS with NIS makes a network transparent to the user.
In the default configuration, NFS completely trusts the network and thus any machine that is connected to a trusted network. Any user with administrator privileges on any computer with physical access to any network the NFS server trusts can access any files that the server makes available.
Often, this level of security is perfectly satisfactory, such as when the network that is trusted is truly private, often localized to a single cabinet or machine room, and no unauthorized access is possible. In other cases the need to trust a whole subnet as a unit is restrictive and there is a need for more fine-grained trust. To meet the need in these cases, NFS supports various security levels using the Kerberos infrastructure. Kerberos requires NFSv4, which is used by default. For details, see Book “Security and Hardening Guide”, Chapter 7 “Network Authentication with Kerberos”.
The following are terms used in the YaST module.
A directory exported by an NFS server, which clients can integrate into their systems.
The NFS client is a system that uses NFS services from an NFS server over the Network File System protocol. The TCP/IP protocol is already integrated into the Linux kernel; there is no need to install any additional software.
The NFS server provides NFS services to clients. A running server depends
on the following daemons: nfsd
(worker), idmapd
(ID-to-name
mapping for NFSv4, needed for certain scenarios only), statd
(file locking), and mountd
(mount requests).
NFSv3 is the version 3 implementation, the “old” stateless NFS that supports client authentication.
NFSv4 is the new version 4 implementation that supports secure user authentication via Kerberos. NFSv4 requires one single port only and thus is better suited for environments behind a firewall than NFSv3.
The protocol is specified as https://datatracker.ietf.org/doc/html/rfc3530.
Parallel NFS, a protocol extension of NFSv4. Any pNFS clients can directly access the data on an NFS server.
For installing and configuring an NFS server, see the SUSE Linux Enterprise Server documentation.
To configure your host as an NFS client, you do not need to install additional software. All needed packages are installed by default.
Authorized users can mount NFS directories from an NFS server into the local file tree using the YaST NFS client module. Proceed as follows:
Start the YaST NFS client module.
Click
in the tab. Enter the host name of the NFS server, the directory to import, and the mount point at which to mount this directory locally.
When using NFSv4, select localdomain
.
To use Kerberos authentication for NFS, GSS security must be enabled. Select
.Enable
in the tab if you use a Firewall and want to allow access to the service from remote computers. The firewall status is displayed next to the check box.Click
to save your changes.
The configuration is written to /etc/fstab
and the
specified file systems are mounted. When you start the YaST configuration
client at a later time, it also reads the existing configuration from this
file.
On (diskless) systems, where the root partition is mounted via network as an NFS share, you need to be careful when configuring the network device with which the NFS share is accessible.
When shutting down or rebooting the system, the default processing order is to turn off network connections, then unmount the root partition. With NFS root, this order causes problems as the root partition cannot be cleanly unmounted as the network connection to the NFS share is already not activated. To prevent the system from deactivating the relevant network device, open the network device configuration tab as described in Section 19.4.1.2.5, “Activating the Network Device” and choose in the pane.
The prerequisite for importing file systems manually from an NFS server is
a running RPC port mapper. The nfs
service takes care to
start it properly; thus, start it by entering systemctl start
nfs
as root
. Then
remote file systems can be mounted in the file system like local partitions
using mount
:
tux >
sudo
mount HOST:REMOTE-PATHLOCAL-PATH
To import user directories from the nfs.example.com
machine, for example, use:
tux >
sudo
mount nfs.example.com:/home /home
To define a count of TCP conncetions that the clients makes to the NFS server, you can use the nconnect
option of the mount
command. You can specify any number between 1 and 16, where 1 is the default value if the mount option has not been specified.
The nconnect
setting is applied only during the first mount process to the particular NFS server. If the same client executes the mount command to the same NFS server, all already established connections will be shared—no new connection will be established. To change the nconnect
setting, you have to unmount all clients connections to the particular NFS server. Then you can define a new value of the nconnect
option.
You can find the current nconnect
value in effect in output of the mount
or in the file /proc/mounts
. If there is no value of the mount option, then the option has not been used during mounting and the default value 1 is in use.
nconnect
As you can close and open connections after the first mount, the actual count of connections necessarily does not have to be the same as the value of nconnect
.
The autofs daemon can be used to mount remote file systems automatically.
Add the following entry to the /etc/auto.master
file:
/nfsmounts /etc/auto.nfs
Now the /nfsmounts
directory acts as the root for all
the NFS mounts on the client if the auto.nfs
file is
filled appropriately. The name auto.nfs
is chosen for
the sake of convenience—you can choose any name. In
auto.nfs
add entries for all the NFS mounts as
follows:
localdata -fstype=nfs server1:/data nfs4mount -fstype=nfs4 server2:/
Activate the settings with systemctl start autofs
as
root
. In this example, /nfsmounts/localdata
,
the /data
directory of
server1
, is mounted with NFS and
/nfsmounts/nfs4mount
from
server2
is mounted with NFSv4.
If the /etc/auto.master
file is edited while the
service autofs is running, the automounter must be restarted for the
changes to take effect with systemctl restart autofs
.
/etc/fstab
#Edit source
A typical NFSv3 mount entry in /etc/fstab
looks like
this:
nfs.example.com:/data /local/path nfs rw,noauto 0 0
For NFSv4 mounts, use nfs4
instead of
nfs
in the third column:
nfs.example.com:/data /local/pathv4 nfs4 rw,noauto 0 0
The noauto
option prevents the file system from being
mounted automatically at start-up. If you want to mount the respective
file system manually, it is possible to shorten the mount command
specifying the mount point only:
tux >
sudo
mount /local/path
If you do not enter the noauto
option, the init
scripts of the system will handle the mount of those file systems at
start-up.
NFS is one of the oldest protocols, developed in the '80s. As such, NFS is usually sufficient if you want to share small files. However, when you want to transfer big files or many clients want to access data, an NFS server becomes a bottleneck and has a significant impact on the system performance. This is because of files quickly getting bigger, whereas the relative speed of your Ethernet has not fully kept up.
When you request a file from a regular NFS server, the server looks up the file metadata, collects all the data and transfers it over the network to your client. However, the performance bottleneck becomes apparent no matter how small or big the files are:
With small files most of the time is spent collecting the metadata.
With big files most of the time is spent on transferring the data from server to client.
pNFS, or parallel NFS, overcomes this limitation as it separates the file system metadata from the location of the data. As such, pNFS requires two types of servers:
A metadata or control server that handles all the non-data traffic
One or more storage server(s) that hold(s) the data
The metadata and the storage servers form a single, logical NFS server. When a client wants to read or write, the metadata server tells the NFSv4 client which storage server to use to access the file chunks. The client can access the data directly on the server.
SUSE Linux Enterprise Desktop supports pNFS on the client side only.
Proceed as described in Procedure 32.1, “Importing NFS Directories”, but click
the check box and optionally . YaST will do all the necessary steps and will write all
the required options in the file /etc/exports
.
Refer to Section 32.3.2, “Importing File Systems Manually” to start. Most of the
configuration is done by the NFSv4 server. For pNFS, the only difference
is to add the minorversion
option and the metadata server
MDS_SERVER to your mount
command:
tux >
sudo
mount -t nfs4 -o minorversion=1 MDS_SERVER MOUNTPOINT
To help with debugging, change the value in the /proc
file system:
tux >
sudo
echo 32767 > /proc/sys/sunrpc/nfsd_debugtux >
sudo
echo 32767 > /proc/sys/sunrpc/nfs_debug
In addition to the man pages of exports
,
nfs
, and mount
, information about
configuring an NFS server and client is available in
/usr/share/doc/packages/nfsidmap/README
. For further
documentation online refer to the following Web sites:
Find the detailed technical documentation online at SourceForge.
For instructions for setting up kerberized NFS, refer to NFS Version 4 Open Source Reference Implementation.
If you have questions on NFSv4, refer to the Linux NFSv4 FAQ.
Using Samba, a Unix machine can be configured as a file and print server for macOS, Windows, and OS/2 machines. Samba has developed into a fully-fledged and rather complex product. Configure Samba with YaST, or by editing the configuration file manually.
The following are some terms used in Samba documentation and in the YaST module.
Samba uses the SMB (server message block) protocol that is based on the NetBIOS services. Microsoft released the protocol so other software manufacturers could establish connections to a Microsoft domain network. With Samba, the SMB protocol works on top of the TCP/IP protocol, so the TCP/IP protocol must be installed on all clients.
The CIFS (common Internet file system) protocol, also known as SMB1 is an early version of the SMB protocol. CIFS defines a standard remote file system access protocol for use over the network, enabling groups of users to work together and share documents across the network. In recent versions of Samba, it is disabled by default for security reasons.
NetBIOS is a software interface (API) designed for communication between machines providing a name service. It enables machines connected to the network to reserve names for themselves. After reservation, these machines can be addressed by name. There is no central process that checks names. Any machine on the network can reserve as many names as it wants as long as the names are not already in use. The NetBIOS interface can be implemented for different network architectures. An implementation that works relatively closely with network hardware is called NetBEUI, but this is often called NetBIOS. Network protocols implemented with NetBIOS are IPX from Novell (NetBIOS via TCP/IP) and TCP/IP.
The NetBIOS names sent via TCP/IP have nothing in common with the names
used in /etc/hosts
or those defined by DNS. NetBIOS
uses its own, completely independent naming convention. However, it is
recommended to use names that correspond to DNS host names to make
administration easier or use DNS natively. This is the default used by
Samba.
Samba server provides SMB/CIFS services and NetBIOS over IP naming services to clients. For Linux, there are three daemons for Samba server: smbd for SMB/CIFS services, nmbd for naming services, and winbind for authentication.
The Samba client is a system that uses Samba services from a Samba server over the SMB protocol. Common operating systems, such as Windows and macOS support the SMB protocol. The TCP/IP protocol must be installed on all computers. Samba provides a client for the different Unix flavors. For Linux, there is a kernel module for SMB that allows the integration of SMB resources on the Linux system level. You do not need to run any daemon for the Samba client.
SMB servers provide resources to the clients by means of shares. Shares are printers and directories with their subdirectories on the server. It is exported by means of a name and can be accessed by its name. The share name can be set to any name—it does not need to be the name of the export directory. A printer is also assigned a name. Clients can access the printer by its name.
A domain controller (DC) is a server that handles accounts in a domain. For data replication, additional domain controllers are available in one domain.
Installing a Samba server is not supported on SUSE Linux Enterprise Desktop. For information about installing and configuring a Samba server, see Administration Guide for SUSE Linux Enterprise Server.
Clients can only access the Samba server via TCP/IP. NetBEUI and NetBIOS via IPX cannot be used with Samba.
Configure a Samba client to access resources (files or printers) on the Samba or Windows server. Enter the NT or Active Directory domain or workgroup in the dialog
› . If you activate , the user authentication runs over the Samba, NT or Kerberos server.
Click pam_mount
man
page.
After completing all settings, confirm the dialog to finish the configuration.
The first version of the SMB network protocol, SMB1 or CIFS, is an old and
insecure protocol which has been deprecated by its originator, Microsoft.
For security reasons, the mount
command on
SUSE Linux Enterprise Desktop will only mount SMB shares using newer protocol versions
by default, namely SMB 2.1, SMB 3.0, or SMB 3.02.
However, this change only affects mount
and
mounting via /etc/fstab
. SMB1 is still
available by explicitly requiring it. Use the following command:
The smbclient
tool.
The Samba server software shipped with SUSE Linux Enterprise Server.
There are setups in which this default setting will lead to connection failures, because only SMB1 can be used:
Setups using an SMB server that does not support newer SMB protocol versions. Windows has offered SMB 2.1 support since Windows 7 and Windows Server 2008.
Setups that rely on SMB1's/CIFS's Unix extensions. These extensions have not been ported to newer protocol versions.
Following the instruction below makes it possible to exploit security issues. For more information about the issues, see https://blogs.technet.microsoft.com/filecab/2016/09/16/stop-using-smb1/.
As soon as possible, upgrade your server to allow for a more secure SMB version.
If you need to enable SMB1 shares on the current SUSE Linux Enterprise Desktop
kernel, add the option vers=1.0
to the
mount
command line you use:
root #
mount -t cifs //HOST/SHARE /MOUNT_POINT –o username=USER_ID,vers=1.0
Alternatively, you can enable SMB1 shares globally within your
SUSE Linux Enterprise Desktop installation.
To do so, add the following to /etc/samba/smb.conf
under the section [global]
:
client min protocol = CORE
In enterprise settings, it is often desirable to allow access only to
users registered on a central instance.
In a Windows-based network, this task is handled by a primary domain
controller (PDC). You can use a Windows NT server configured as PDC, but
this task can also be done with a Samba server. The entries that must be
made in the [global]
section of
smb.conf
are shown in
Example 33.1, “Global Section in smb.conf”.
[global] workgroup = WORKGROUP domain logons = Yes domain master = Yes
It is necessary to prepare user accounts and passwords in an encryption
format that conforms with Windows. Do this with the command
smbpasswd
-a name
. Create the domain
account for the computers, required by the Windows domain concept, with the
following commands:
useradd hostname smbpasswd -a -m hostname
With the useradd
command, a dollar sign is added. The
command smbpasswd
inserts this automatically when the
parameter -m
is used. The commented configuration example
(/usr/share/doc/packages/samba/examples/smb.conf.SUSE
)
contains settings that automate this task.
add machine script = /usr/sbin/useradd -g nogroup -c "NT Machine Account" \ -s /bin/false %m
To make sure that Samba can execute this script correctly, choose a Samba
user with the required administrator permissions and add it to the
ntadmin
group. Then all users
belonging to this Linux group can be assigned Domain
Admin
status with the command:
net groupmap add ntgroup="Domain Admins" unixgroup=ntadmin
This section introduces more advanced techniques to manage both the client and server part of the Samba suite.
systemd
#Edit source
You can use systemd
to mount CIFS shares on startup. To do so, proceed as
described further:
Create the mount points:
tux >
mkdir -p PATH_SERVER_SHARED_FOLDER
where PATH_SERVER_SHARED_FOLDER is
/cifs/shared
in further steps.
Create the systemd
unit file and generate a file name from the path
specified in the previous step where "/" are replaced with "-", for
example:
tux >
sudo
touch /etc/systemd/system/cifs-shared.mount
with the following content:
[Unit] Description=CIFS share from The-Server [Mount] What=//The-Server/Shared-Folder Where=/cifs/shared Type=cifs Options=rw,username=vagrant,password=admin [Install] WantedBy=multi-user.target
Enable the service:
tux >
sudo
systemctl enable cifs-shared.mount
Start the service:
tux >
sudo
systemctl start cifs-shared.mount
To verify that the service is running, run the command:
tux >
sudo
systemctl status cifs-shared.mount
To confirm that the CIFS shared path is available, try the following command:
tux >
cd /cifs/sharedtux >
ls -l total 0 -rwxrwxrwx. 1 root root 0 Oct 24 22:31 hello-world-cifs.txt drwxrwxrwx. 2 root root 0 Oct 24 22:31 subfolder -rw-r--r--. 1 vagrant vagrant 0 Oct 28 21:51 testfile.txt
Samba allows clients to remotely manipulate file and directory compression flags for shares placed on the Btrfs file system. Windows Explorer provides the ability to flag files/directories for transparent compression via the
› › dialog:Files flagged for compression are transparently compressed and decompressed by the underlying file system when accessed or modified. This normally results in storage capacity savings at the expense of extra CPU overhead when accessing the file. New files and directories inherit the compression flag from the parent directory, unless created with the FILE_NO_COMPRESSION option.
Windows Explorer presents compressed files and directories visually differently to those that are not compressed:
You can enable Samba share compression either manually by adding
vfs objects = btrfs
to the share configuration in /etc/samba/smb.conf
, or
using YaST: › › , and checking
.
Snapshots, also called Shadow Copies, are copies of the state of a file system subvolume at a certain point of time. Snapper is the tool to manage these snapshots in Linux. Snapshots are supported on the Btrfs file system or thinly-provisioned LVM volumes. The Samba suite supports managing remote snapshots through the FSRVP protocol on both the server and client side.
Snapshots on a Samba server can be exposed to remote Windows clients as file or directory previous versions.
To enable snapshots on a Samba server, the following conditions must be fulfilled:
The SMB network share resides on a Btrfs subvolume.
The SMB network share path has a related snapper configuration file. You can create the snapper file with
tux >
sudo
snapper -c <cfg_name> create-config/path/to/share
For more information on snapper, see Chapter 7, System Recovery and Snapshot Management with Snapper.
The snapshot directory tree must allow access for relevant users. For
more information, see the PERMISSIONS section of the vfs_snapper manual
page (man 8 vfs_snapper
).
To support remote snapshots, you need to modify the
/etc/samba/smb.conf
file. You can do it either with
› › , or
manually by enhancing the relevant share section with
vfs objects = snapper
Note that you need to restart the Samba service for manual
smb.conf
changes to take effect:
tux >
sudo
systemctl restart nmb smb
After being configured, snapshots created by snapper for the Samba share path can be accessed from Windows Explorer from a file or directory's
tab.By default, snapshots can only be created and deleted on the Samba server locally, via the snapper command line utility, or using snapper's time line feature.
Samba can be configured to process share snapshot creation and deletion requests from remote hosts using the File Server Remote VSS Protocol (FSRVP).
In addition to the configuration and prerequisites documented in
Section 33.5.3.1, “Previous Versions”, the following global
configuration is required in /etc/samba/smb.conf
:
[global] rpc_daemon:fssd = fork registry shares = yes include = registry
FSRVP clients, including Samba's rpcclient
and Windows
Server 2012 DiskShadow.exe
, can then instruct Samba to
create or delete a snapshot for a given share, and expose the snapshot as
a new share.
rpcclient
#Edit source
The samba-client
package contains an FSRVP client
that can remotely request a Windows/Samba server to create and expose a
snapshot of a given share. You can then use existing tools in
SUSE Linux Enterprise Desktop to mount the exposed share and back up its files. Requests
to the server are sent using the rpcclient
binary.
rpcclient
to Request a Windows Server 2012 Share Snapshot #
Connect to win-server.example.com
server as an
administrator in an EXAMPLE
domain:
root #
rpcclient -U 'EXAMPLE\Administrator' ncacn_np:win-server.example.com[ndr64,sign]
Enter EXAMPLE/Administrator's password:
Check that the SMB share is visible for rpcclient
:
root #
rpcclient $> netshareenum
netname: windows_server_2012_share
remark:
path: C:\Shares\windows_server_2012_share
password: (null)
Check that the SMB share supports snapshot creation:
root #
rpcclient $> fss_is_path_sup windows_server_2012_share \
UNC \\WIN-SERVER\windows_server_2012_share\ supports shadow copy requests
Request the creation of a share snapshot:
root #
rpcclient $> fss_create_expose backup ro windows_server_2012_share
13fe880e-e232-493d-87e9-402f21019fb6: shadow-copy set created
13fe880e-e232-493d-87e9-402f21019fb6(1c26544e-8251-445f-be89-d1e0a3938777): \
\\WIN-SERVER\windows_server_2012_share\ shadow-copy added to set
13fe880e-e232-493d-87e9-402f21019fb6: prepare completed in 0 secs
13fe880e-e232-493d-87e9-402f21019fb6: commit completed in 1 secs
13fe880e-e232-493d-87e9-402f21019fb6(1c26544e-8251-445f-be89-d1e0a3938777): \
share windows_server_2012_share@{1C26544E-8251-445F-BE89-D1E0A3938777} \
exposed as a snapshot of \\WIN-SERVER\windows_server_2012_share\
Confirm that the snapshot share is exposed by the server:
root #
rpcclient $> netshareenum
netname: windows_server_2012_share
remark:
path: C:\Shares\windows_server_2012_share
password: (null)
netname: windows_server_2012_share@{1C26544E-8251-445F-BE89-D1E0A3938777}
remark: (null)
path: \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy{F6E6507E-F537-11E3-9404-B8AC6F927453}\Shares\windows_server_2012_share\
password: (null)
Attempt to delete the snapshot share:
root #
rpcclient $> fss_delete windows_server_2012_share \
13fe880e-e232-493d-87e9-402f21019fb6 1c26544e-8251-445f-be89-d1e0a3938777
13fe880e-e232-493d-87e9-402f21019fb6(1c26544e-8251-445f-be89-d1e0a3938777): \
\\WIN-SERVER\windows_server_2012_share\ shadow-copy deleted
Confirm that the snapshot share has been removed by the server:
root #
rpcclient $> netshareenum
netname: windows_server_2012_share
remark:
path: C:\Shares\windows_server_2012_share
password: (null)
DiskShadow.exe
#Edit source
You can manage snapshots of SMB shares on the Linux Samba server from the
Windows environment acting as a client as well. Windows Server 2012
includes the DiskShadow.exe
utility that can manage
remote shares similar to the rpcclient
described in
Section 33.5.3.3, “Managing Snapshots Remotely from Linux with rpcclient
”. Note that you
need to carefully set up the Samba server first.
Following is an example procedure to set up the Samba server so that the
Windows Server client can manage its share's snapshots. Note that EXAMPLE
is the Active Directory domain used in the testing environment,
fsrvp-server.example.com
is the host name of the Samba server, and
/srv/smb
is the path to the SMB share.
Join Active Directory domain via YaST.
Ensure that the Active Domain DNS entry was correct:
fsrvp-server:~ # net -U 'Administrator' ads dns register \ fsrvp-server.example.com <IP address> Successfully registered hostname with DNS
Create Btrfs subvolume at /srv/smb
fsrvp-server:~ # btrfs subvolume create /srv/smb
Create snapper configuration file for path /srv/smb
fsrvp-server:~ # snapper -c <snapper_config> create-config /srv/smb
Create new share with path /srv/smb
, and YaST
check box enabled. Make sure to add
the following snippets to the global section of
/etc/samba/smb.conf
as mentioned in
Section 33.5.3.2, “Remote Share Snapshots”:
[global] rpc_daemon:fssd = fork registry shares = yes include = registry
Restart Samba with systemctl restart nmb smb
Configure snapper permissions:
fsrvp-server:~ # snapper -c <snapper_config> set-config \ ALLOW_USERS="EXAMPLE\\\\Administrator EXAMPLE\\\\win-client$"
Ensure that any ALLOW_USERS are also permitted traversal of the
.snapshots
subdirectory.
fsrvp-server:~ # snapper -c <snapper_config> set-config SYNC_ACL=yes
Be careful about the '\' escapes! Escape twice to ensure that the value
stored in
/etc/snapper/configs/<snapper_config>
is
escaped once.
"EXAMPLE\win-client$" corresponds to the Windows client computer account. Windows issues initial FSRVP requests while authenticated with this account.
Grant Windows client account necessary privileges:
fsrvp-server:~ # net -U 'Administrator' rpc rights grant \ "EXAMPLE\\win-client$" SeBackupPrivilege Successfully granted rights.
The previous command is not needed for the "EXAMPLE\Administrator" user, which has privileges already granted.
DiskShadow.exe
in Action #Boot Windows Server 2012 (example host name WIN-CLIENT).
Join the same Active Directory domain EXAMPLE as with the SUSE Linux Enterprise Desktop.
Reboot.
Open Powershell.
Start DiskShadow.exe
and begin the backup procedure:
PS C:\Users\Administrator.EXAMPLE> diskshadow.exe Microsoft DiskShadow version 1.0 Copyright (C) 2012 Microsoft Corporation On computer: WIN-CLIENT, 6/17/2014 3:53:54 PM DISKSHADOW> begin backup
Specify that shadow copy persists across program exit, reset or reboot:
DISKSHADOW> set context PERSISTENT
Check whether the specified share supports snapshots, and create one:
DISKSHADOW> add volume \\fsrvp-server\sles_snapper DISKSHADOW> create Alias VSS_SHADOW_1 for shadow ID {de4ddca4-4978-4805-8776-cdf82d190a4a} set as \ environment variable. Alias VSS_SHADOW_SET for shadow set ID {c58e1452-c554-400e-a266-d11d5c837cb1} \ set as environment variable. Querying all shadow copies with the shadow copy set ID \ {c58e1452-c554-400e-a266-d11d5c837cb1} * Shadow copy ID = {de4ddca4-4978-4805-8776-cdf82d190a4a} %VSS_SHADOW_1% - Shadow copy set: {c58e1452-c554-400e-a266-d11d5c837cb1} %VSS_SHADOW_SET% - Original count of shadow copies = 1 - Original volume name: \\FSRVP-SERVER\SLES_SNAPPER\ \ [volume not on this machine] - Creation time: 6/17/2014 3:54:43 PM - Shadow copy device name: \\FSRVP-SERVER\SLES_SNAPPER@{31afd84a-44a7-41be-b9b0-751898756faa} - Originating machine: FSRVP-SERVER - Service machine: win-client.example.com - Not exposed - Provider ID: {89300202-3cec-4981-9171-19f59559e0f2} - Attributes: No_Auto_Release Persistent FileShare Number of shadow copies listed: 1
Finish the backup procedure:
DISKSHADOW> end backup
After the snapshot was created, try to delete it and verify the deletion:
DISKSHADOW> delete shadows volume \\FSRVP-SERVER\SLES_SNAPPER\ Deleting shadow copy {de4ddca4-4978-4805-8776-cdf82d190a4a} on volume \ \\FSRVP-SERVER\SLES_SNAPPER\ from provider \ {89300202-3cec-4981-9171-19f59559e0f2} [Attributes: 0x04000009]... Number of shadow copies deleted: 1 DISKSHADOW> list shadows all Querying all shadow copies on the computer ... No shadow copies found in system.
Man Pages:
To see a list of all man pages installed with the package
samba, run apropos samba
.
Open any of the man pages with
man NAME_OF_MAN_PAGE
.
SUSE-specific README file:
The package samba-client contains the file
/usr/share/doc/packages/samba/README.SUSE
.
Additional Packaged Documentation:
Install the package samba-doc
with
zypper install samba-doc
.
This documentation installs into
/usr/share/doc/packages/samba
. It contains an HTML
version of the man pages and a library of example configurations
(such as smb.conf.SUSE
).
Online Documentation: The Samba wiki contains extensive User Documentation at https://wiki.samba.org/index.php/User_Documentation.
autofs
is a program that automatically mounts
specified directories on an on-demand basis. It is based on a kernel module
for high efficiency, and can manage both local directories and network
shares. These automatic mount points are mounted only when they are
accessed, and unmounted after a certain period of inactivity. This
on-demand behavior saves bandwidth and results in better performance than
static mounts managed by /etc/fstab
. While
autofs
is a control script,
automount
is the command (daemon) that does the actual
auto-mounting.
autofs
is not installed on SUSE Linux Enterprise Desktop by
default. To use its auto-mounting capabilities, first install it with
tux >
sudo
zypper install autofs
You need to configure autofs
manually by editing
its configuration files with a text editor, such as vim
.
There are two basic steps to configure
autofs
—the master map
file, and specific map files.
The default master configuration file for autofs
is /etc/auto.master
. You can change its location by
changing the value of the DEFAULT_MASTER_MAP_NAME
option
in /etc/sysconfig/autofs
. Here is the content of the
default one for SUSE Linux Enterprise Desktop:
# # Sample auto.master file # This is an automounter map and it has the following format # key [ -mount-options-separated-by-comma ] location # For details of the format look at autofs(5).1 # #/misc /etc/auto.misc2 #/net -hosts # # Include /etc/auto.master.d/*.autofs3 # #+dir:/etc/auto.master.d # # Include central master map if it can be found using # nsswitch sources. # # Note that if there are entries for /net or /misc (as # above) in the included master map any keys that are the # same will not be seen as the first read key seen takes # precedence. # +auto.master4
The | |
Although commented out (#) by default, this is an example of a simple automounter mapping syntax. | |
In case you need to split the master map into several files, uncomment
the line, and put the mappings (suffixed with | |
|
Entries in auto.master
have three fields with the
following syntax:
mount point map name options
The base location where to mount the autofs
file system, such as /home
.
The name of a map source to use for mounting. For the syntax of the maps files, see Section 34.2.2, “Map Files”.
These options (if specified) will apply as defaults to all entries in the given map.
For more detailed information on the specific values of the optional
map-type
, format
, and
options
, see the manual
page (man 5 auto.master
).
The following entry in auto.master
tells
autofs
to look in
/etc/auto.smb
, and create mount points in the
/smb
directory.
/smb /etc/auto.smb
Direct mounts create a mount point at the path specified inside the
relevant map file. Instead of specifying the mount point in
auto.master
, replace the mount point field with
/-
. For example, the following line tells
autofs
to create a mount point at the place
specified in auto.smb
:
/- /etc/auto.smb
If the map file is not specified with its full local or network path, it is located using the Name Service Switch (NSS) configuration:
/- auto.smb
Although files are the most common types of maps for
auto-mounting with autofs
, there are other types
as well. A map specification can be the output of a command, or a result
of a query in LDAP or database. For more detailed information on map
types, see the manual page man 5 auto.master
.
Map files specify the (local or network) source location, and the mount point where to mount the source locally. The general format of maps is similar to the master map. The difference is that the options appear between the mount point and the location instead of at the end of the entry:
mount point options location
Make sure that map files are not marked as executable. You can remove
the executable bits by executing chmod -x MAP_FILE
.
Specifies where to mount the source location. This can be either a
single directory name (so-called indirect mount) to
be added to the base mount point specified in
auto.master
, or the full path of the mount point
(direct mount, see Section 34.2.1.1, “Direct Mounts”).
Specifies optional comma-separated list of mount options for the
relevant entries. If auto.master
contains options
for this map file as well, theses are appended.
Specifies from where the file system is to be mounted. It is usually an
NFS or SMB volume in the usual notation
host_name:path_name
. If the file system to be mounted
begins with a '/' (such as local /dev
entries or
smbfs shares), a colon symbol ':' needs to be prefixed, such as
:/dev/sda1
.
This section introduces information on how to control the
autofs
service operation, and how to view more
debugging information when tuning the automounter operation.
autofs
Service #Edit source
The operation of the autofs
service is controlled
by systemd
. The general syntax of the systemctl
command for autofs
is
tux >
sudo
systemctl SUB_COMMAND autofs
where SUB_COMMAND is one of:
Starts the automounter daemon at boot.
Starts the automounter daemon.
Stops the automounter daemon. Automatic mount points are not accessible.
Prints the current status of the autofs
service
together with a part of a relevant log file.
Stops and starts the automounter, terminating all running daemons and starting new ones.
Checks the current auto.master
map, restarts those
daemons whose entries have changed, and starts new ones for new entries.
If you experience problems when mounting directories with
autofs
, it is useful to run the
automount
daemon manually and watch its output messages:
Stop autofs
.
tux >
sudo
systemctl stop autofs
From one terminal, run automount
manually in the
foreground, producing verbose output.
tux >
sudo
automount -f -v
From another terminal, try to mount the auto-mounting file systems by
accessing the mount points (for example by cd
or
ls
).
Check the output of automount
from the first terminal
for more information why the mount failed, or why it was not even
attempted.
The following procedure illustrates how to configure
autofs
to auto-mount an NFS share available on your
network. It uses the information mentioned above, and assumes you
are familiar with NFS exports. For more information on NFS, see
Chapter 32, Sharing File Systems with NFS.
Edit the master map file /etc/auto.master
:
tux >
sudo
vim /etc/auto.master
Add a new entry for the new NFS mount at the end of
/etc/auto.master
:
/nfs /etc/auto.nfs --timeout=10
It tells autofs
that the base mount point is
/nfs
, the NFS shares are specified in the
/etc/auto.nfs
map, and that all shares in this map
will be automatically unmounted after 10 seconds of inactivity.
Create a new map file for NFS shares:
tux >
sudo
vim /etc/auto.nfs
/etc/auto.nfs
normally contains a separate line for
each NFS share. Its format is described in
Section 34.2.2, “Map Files”. Add the line describing the mount point
and the NFS share network address:
export jupiter.com:/home/geeko/doc/export
The above line means that the /home/geeko/doc/export
directory on the jupiter.com
host will be auto-mounted
to the /nfs/export
directory on the local host
(/nfs
is taken from the
auto.master
map) when requested. The
/nfs/export
directory will be created automatically
by autofs
.
Optionally comment out the related line in /etc/fstab
if you previously mounted the same NFS share statically. The line should
look similar to this:
#jupiter.com:/home/geeko/doc/export /nfs/export nfs defaults 0 0
Reload autofs
and check if it works:
tux >
sudo
systemctl restart autofs
# ls -l /nfs/export total 20 drwxr-xr-x 5 1001 users 4096 Jan 14 2017 .images/ drwxr-xr-x 10 1001 users 4096 Aug 16 2017 .profiled/ drwxr-xr-x 3 1001 users 4096 Aug 30 2017 .tmp/ drwxr-xr-x 4 1001 users 4096 Apr 25 08:56 manual/
If you can see the list of files on the remote share, then
autofs
is functioning.
This section describes topics that are beyond the basic introduction to
autofs
—auto-mounting of NFS shares that are
available on your network, using wild cards in map files, and information
specific to the CIFS file system.
/net
Mount Point #Edit source
This helper mount point is useful if you use a lot of NFS shares.
/net
auto-mounts all NFS shares on your local network
on demand. The entry is already present in the
auto.master
file, so all you need to do is uncomment
it and restart autofs
:
/net -hosts
tux >
sudo
systemctl restart autofs
For example, if you have a server named jupiter
with an
NFS share called /export
, you can mount it by typing
tux >
sudo
cd /net/jupiter/export
on the command line.
If you have a directory with subdirectories that you need to auto-mount
individually—the typical case is the /home
directory with individual users' home directories inside—
autofs
offers a clever solution for that.
In case of home directories, add the following line in
auto.master
:
/home /etc/auto.home
Now you need to add the correct mapping to the
/etc/auto.home
file, so that the users' home
directories are mounted automatically. One solution is to create separate
entries for each directory:
wilber jupiter.com:/home/wilber penguin jupiter.com:/home/penguin tux jupiter.com:/home/tux [...]
This is very awkward as you need to manage the list of users inside
auto.home
. You can use the asterisk '*' instead of the
mount point, and the ampersand '&' instead of the directory to be
mounted:
* jupiter:/home/&
If you want to auto-mount an SMB/CIFS share (see
Chapter 33, Samba for more information on the SMB/CIFS protocol),
you need to modify the syntax of the map file. Add
-fstype=cifs
in the option field, and prefix the share
location with a colon ':'.
mount point -fstype=cifs ://jupiter.com/export
SUSE® Linux Enterprise Desktop comes with various sources of information and documentation, many of which are already integrated into your installed system.
For a quick overview of all relevant system information of a machine,
SUSE Linux Enterprise Desktop offers the
hostinfo
package. It also helps
system administrators to check for tainted kernels (that are not supported)
or any third-party packages installed on a machine.
In case of problems, a detailed system report may be created with either
the supportconfig
command line tool or the YaST
module. Both will collect information about the
system such as: current kernel version, hardware, installed packages,
partition setup, and much more. The result is a TAR archive of files. After
opening a Service Request (SR), you can upload the TAR archive to Global
Technical Support. It will help to locate the issue you reported and to
assist you in solving the problem.
Additionally, you can analyze the supportconfig
output
for known issues to help resolve problems faster. For this purpose,
SUSE Linux Enterprise Desktop provides both an appliance and a command line tool for
Supportconfig Analysis
(SCA).
This chapter describes a range of potential problems and their solutions. Even if your situation is not precisely listed here, there may be one similar enough to offer hints to the solution of your problem.
SUSE® Linux Enterprise Desktop comes with various sources of information and documentation, many of which are already integrated into your installed system.
/usr/share/doc
This traditional help directory holds various documentation files and
release notes for your system. It contains also information of installed
packages in the subdirectory packages
. Find more
detailed information in Section 35.1, “Documentation Directory”.
When working with the shell, you do not need to know the options of the commands by heart. Traditionally, the shell provides integrated help by means of man pages and info pages. Read more in Section 35.2, “Man Pages” and Section 35.3, “Info Pages”.
The help center of the GNOME desktop (Help) provides central access to the most important documentation resources on your system in searchable form. These resources include online help for installed applications, man pages, info pages, and the SUSE manuals delivered with your product.
When installing new software with YaST, the software documentation is usually installed automatically and appears in the help center of your desktop. However, some applications, such as GIMP, may have different online help packages that can be installed separately with YaST and do not integrate into the help centers.
The traditional directory to find documentation on your
installed Linux system is /usr/share/doc
. Usually, the
directory contains information about the packages installed on your system,
plus release notes, manuals, and more.
In the Linux world, many manuals and other kinds of documentation are
available in the form of packages, like software. How much and which
information you find in /usr/share/docs
also depends
on the (documentation) packages installed. If you cannot find the
subdirectories mentioned here, check if the respective packages are
installed on your system and add them with YaST, if needed.
We provide HTML and PDF versions of our books in different
languages. In the manual
subdirectory, find HTML
versions of most of the SUSE manuals available for your product. For an
overview of all documentation available for your product refer to the
preface of the manuals.
If more than one language is installed,
/usr/share/doc/manual
may contain different language
versions of the manuals. The HTML versions of the SUSE manuals are also
available in the help center of both desktops. For information on where to
find the PDF and HTML versions of the books on your installation media,
refer to the SUSE Linux Enterprise Desktop Release Notes. They are available on your
installed system under /usr/share/doc/release-notes/
or online at your product-specific Web page at https://www.suse.com/releasenotes//.
Under packages
, find the documentation
that is included in the software packages installed on your system. For
every package, a subdirectory
/usr/share/doc/packages/PACKAGENAME
is created. It often contains README files for the package and sometimes
examples, configuration files, or additional scripts. The following list
introduces typical files to be found under
/usr/share/doc/packages
. None of these entries are
mandatory and many packages might only include a few of them.
AUTHORS
List of the main developers.
BUGS
Known bugs or malfunctions. Might also contain a link to a Bugzilla Web page where you can search all bugs.
CHANGES
, ChangeLog
Summary of changes from version to version. Usually interesting for developers, because it is very detailed.
COPYING
, LICENSE
Licensing information.
FAQ
Question and answers collected from mailing lists or newsgroups.
INSTALL
How to install this package on your system. As the package is already installed by the time you get to read this file, you can safely ignore the contents of this file.
README
, README.*
General information on the software. For example, for what purpose and how to use it.
TODO
Things that are not implemented yet, but probably will be in the future.
MANIFEST
List of files with a brief summary.
NEWS
Description of what is new in this version.
Man pages are an essential part of any Linux system. They explain the usage
of a command and all available options and parameters. Man pages can be
accessed with man
followed by the name of the command,
for example, man ls
.
Man pages are displayed directly in the shell. To navigate them, move up and
down with Page ↑ and Page ↓.
Move between the beginning and the end of a document with
Home and End. End this viewing
mode by pressing Q. Learn more about the
man
command itself with man man
. Man
pages are sorted in categories as shown in
Table 35.1, “Man Pages—Categories and Descriptions” (taken from the man page for man
itself).
Number |
Description |
---|---|
1 |
Executable programs or shell commands |
2 |
System calls (functions provided by the kernel) |
3 |
Library calls (functions within program libraries) |
4 |
Special files (usually found in |
5 |
File formats and conventions ( |
6 |
Games |
7 |
Miscellaneous (including macro packages and conventions), for example, man(7), groff(7) |
8 |
System administration commands (usually only for |
9 |
Kernel routines (nonstandard) |
Each man page consists of several parts labeled NAME , SYNOPSIS , DESCRIPTION , SEE ALSO , LICENSING , and AUTHOR . There may be additional sections available depending on the type of command.
Info pages are another important source of information on your system.
Usually, they are more detailed than man pages. They consist of more than
command line options and contain sometimes whole tutorials or reference
documentation. To view the info page for a certain command, enter
info
followed by the name of the command, for example,
info ls
. You can browse an info page with a viewer
directly in the shell and display the different sections, called
“nodes”. Use Space to move forward and
<— to move backward. Within a node, you can also
browse with Page ↑ and Page ↓
but only Space and <— will
take you also to the previous or subsequent node. Press Q
to end the viewing mode. Not every command comes with an info page and vice
versa.
In addition to the online versions of the SUSE manuals installed under
/usr/share/doc
, you can also access the
product-specific manuals and documentation on the Web. For an overview of
all documentation available for SUSE Linux Enterprise Desktop check out your
product-specific documentation Web page at
https://documentation.suse.com/.
If you are searching for additional product-related information, you can also refer to the following Web sites:
The SUSE Technical Support can be found at https://www.suse.com/support/ if you have questions or need solutions for technical problems.
The SUSE blog offers articles, tips, Q and A: https://www.suse.com/c/blog/
Documentation for GNOME users, administrators and developers is available at https://library.gnome.org/.
The Linux Documentation Project (TLDP) is run by a team of volunteers who write Linux-related documentation (see https://www.tldp.org). It is probably the most comprehensive documentation resource for Linux. The set of documents contains tutorials for beginners, but is mainly focused on experienced users and professional system administrators. TLDP publishes HOWTOs, FAQs, and guides (handbooks) under a free license. Parts of the documentation from TLDP are also available on SUSE Linux Enterprise Desktop.
You can also try general-purpose search engines. For example, use the search
terms Linux CD-RW help
or OpenOffice file
conversion problem
if you have trouble with burning CDs or LibreOffice
file conversion.
For a quick overview of all relevant system information of a machine,
SUSE Linux Enterprise Desktop offers the
hostinfo
package. It also helps
system administrators to check for tainted kernels (that are not supported)
or any third-party packages installed on a machine.
In case of problems, a detailed system report may be created with either
the supportconfig
command line tool or the YaST
module. Both will collect information about the
system such as: current kernel version, hardware, installed packages,
partition setup, and much more. The result is a TAR archive of files. After
opening a Service Request (SR), you can upload the TAR archive to Global
Technical Support. It will help to locate the issue you reported and to
assist you in solving the problem.
Additionally, you can analyze the supportconfig
output
for known issues to help resolve problems faster. For this purpose,
SUSE Linux Enterprise Desktop provides both an appliance and a command line tool for
Supportconfig Analysis
(SCA).
For a quick and easy overview of all relevant system information when
logging in to a server, use the package
hostinfo
. After it has been
installed on a machine, the console displays the following information to
any root
user that logs in to this machine:
hostinfo
When Logging In as root
#Welcome to SUSE Linux Enterprise Server 15 (x86_64) - Kernel \r (\l). Distribution: SUSE Linux Enterprise Server 15 SP0 Current As Of: Mon Jun 10 12:02:21 2019 Hostname: earth Kernel Version: 4.12.14-150.14-default Architecture: x86_64 Installed: Mon Apr 29 14:34:30 2019 Status: Not Tainted Last Installed Package: Mon Jun 10 11:56:07 2019 Patches Needed: 62 Security: 26 3rd Party Packages: 9 Network Interfaces eth0: 192.168.2/24 2002:c0a8:20a::/64 Memory Total/Free/Avail: 7.5G/5.7G/6.4G (86% Avail) CPU Load Average: 6 (3%) with 2 CPUs SSH Host Keys (RSA): SHA256:AaBior5diakoA+AeNUgPEwsVA0/uM6Ako7PSnDfXV2E (DSA): SHA256:Ky3SofWZduR208ikVdYOGFQM4OTWHKubDGaClHJgHuM (ECDSA): SHA256:styGTl+QWSDk0F3HFF31Kamk1KEVnMHin9DIaqbIFZI (ED25519): SHA256:MXmPSNczpF2SfyCWB92k++Yl+md5ncxSdEvyQLzkuEE Storage Devices /dev/sda: 60 GiB
In case the output shows a tainted
kernel status, see
Section 36.6, “Support of Kernel Modules” for more details.
To create a TAR archive with detailed system information that you can hand over to Global Technical Support, use either:
the command supportconfig
or,
the YaST
module.
The command line tool is provided by the
package supportutils
which is installed by default.
The YaST module is also based on the command
line tool.
Depending on which packages are installed on your system, some of these
packages integrate Supportconfig plug-ins. When Supportconfig is executed,
all plug-ins are executed as well and create one or more result files for
the archive. That has the benefit that the only topics checked are those
that contain a specific plug-in for them. Supportconfig plug-ins are stored
in the directory /usr/lib/supportconfig/plugins/
.
Supportconfig archives can be generated at any time. However, for handing over the Supportconfig data to Global Technical Support, you need to generate a service request number first. You will need it to upload the archive to support.
To create a service request, go to https://scc.suse.com/support/requests and follow the instructions on the screen. Write down the service request number.
SUSE treats system reports as confidential data. For details about our privacy commitment, see https://www.suse.com/company/policies/privacy/.
After having created a service request number, you can upload your Supportconfig archives to Global Technical Support as described in Procedure 36.1, “Submitting Information to Support with YaST” or Procedure 36.2, “Submitting Information to Support from Command Line”. Use one of the following upload targets:
North America: FTP ftp://support-ftp.us.suse.com/incoming/, FTPS ftps://support-ftp.us.suse.com/incoming/
EMEA, Europe, the Middle East, and Africa: FTP ftp://support-ftp.emea.suse.com/incoming, FTPS ftps://support-ftp.emea.suse.com/incoming
Alternatively, you can manually attach the TAR archive to your service request using the service request URL: https://scc.suse.com/support/requests.
To use YaST to gather your system information, proceed as follows:
Start YaST and open the
module.Click
.
In the next window, select one of the Supportconfig options from the
radio button list. supportconfig
man page.
Press
.
Enter your contact information. It is saved in the
basic-environment.txt
file and included in the
created archive.
To submit the archive to Global Technical Support, provide the required Section 36.2.2, “Upload Targets” for details of which upload servers are available.
. YaST automatically suggests an upload server. To modify it, refer toTo submit the archive later, leave the
empty.Press
to start the information collection process.After the process is finished, press
.To review the collected data, select the desired file from
to view its contents in YaST. To remove a file from the TAR archive before submitting it to support, use . Press .
Save the TAR archive. If you started the YaST module as root
user, YaST prompts to save the archive to /var/log
(otherwise, to your home directory). The file name format is
scc_HOST_DATE_TIME.tbz
.
To upload the archive to support directly, make sure Step 5. To modify the upload target, check which upload servers are available in Section 36.2.2, “Upload Targets”.
is activated. The shown here is the one that YaST suggests inTo skip the upload, deactivate
.Confirm the changes to close the YaST module.
The following procedure shows how to create a Supportconfig archive, but without submitting it to support directly. For uploading it, you need to run the command with certain options as described in Procedure 36.2, “Submitting Information to Support from Command Line”.
Open a shell and become root
.
Run supportconfig
. Usually, it is enough to
run this tool without any options. Some options are very common and
are displayed in the following list:
-E MAIL
, -N NAME
, -O COMPANY
, -P PHONE
Sets your contact data: e-mail address (-E
), company
name (-O
), your name (-N
), and
your phone number (-P
).
-i KEYWORDS
, -F
Limits the features to check. The placeholder KEYWORDS
is a comma separated list of case-sensitive keywords. Get a list
of all keywords with supportconfig -F
.
-r SRNUMBER
Defines your service request number when uploading the generated TAR archive.
Wait for the tool to complete the operation.
The default archive location is /var/log
, with the
file name format being
scc_HOST_DATE_TIME.tbz
supportconfig
#Edit source
Whether you run supportconfig
through YaST or directly,
the script gives you a summary of what it did.
Support Utilities - Supportconfig Script Version: 3.0-98 Script Date: 2017 06 01 [...] Gathering system information Data Directory: /var/log/scc_d251_180201_1525 1 Basic Server Health Check... Done 2 RPM Database... Done 2 Basic Environment... Done 2 System Modules... Done 2 [...] File System List... Skipped 3 [...] Command History... Excluded 4 [...] Supportconfig Plugins: 1 5 Plugin: pstree... Done [...] Creating Tar Ball ==[ DONE ]=================================================================== Log file tar ball: /var/log/scc_d251_180201_1525.txz 6 Log file size: 732K Log file md5sum: bf23e0e15e9382c49f92cbce46000d8b =============================================================================
The temporary data directory to store the results. This directory is archived as tar file, see 6. | |
The feature was enabled (either by default or selected manually) and executed successfully. The result is stored in a file (see Table 36.1, “Comparison of Features and File Names in the TAR Archive”). | |
The feature was skipped because some files of one or more RPM packages were changed. | |
The feature was excluded because it was deselected via the | |
The script found one plug-in and executes the plug-in
| |
The tar file name of the archive, by default compressed with |
The supportconfig
utility is usually called without any
options. Display a list of all options with
supportconfig
-h
or refer to the man
page. The following list gives a brief overview of some common use cases:
Use the minimal option (-m
):
tux >
sudo
supportconfig -m
If you have already localized a problem that relates
to a specific area or feature set only, you should limit the collected
information to the specific area for the next
supportconfig
run. For example, if you detected
problems with LVM and want to test a recent change that you did to the
LVM configuration. In that case it makes sense to gather the minimum
Supportconfig information around LVM only:
tux >
sudo
supportconfig -i LVM
Additional keywords can be separated through commas. For example, an additional disk test:
tux >
sudo
supportconfig -i LVM,DISK
For a complete list of feature keywords that you can use for limiting the collected information to a specific area, run:
tux >
sudo
supportconfig -F
tux >
sudo
supportconfig -E tux@example.org -N "Tux Penguin" -O "Penguin Inc." ...
(all in one line)
tux >
sudo
supportconfig -l
This is especially useful in high logging environments or after a kernel crash when syslog rotates the log files after a reboot.
The TAR archive contains all the results from the features. Depending on
what you have selected (all or only a small set), the archive can contain
more or less files.
The set of features can be limited through the -i
option (see Section 36.2.6, “Common Supportconfig Options”).
To list the content of the archive, use the following tar
command:
root #
tar
xf /var/log/scc_earth_180131_1545.tbz
The following file names are always available inside the TAR archive:
basic-environment.txt
Contains the date when this script was executed and system information like version of the distribution, hypervisor information, and more.
basic-health-check.txt
Contains some basic health checks like uptime, virtual memory statistics, free memory and hard disk, checks for zombie processes, and more.
hardware.txt
Contains basic hardware checks like information about the CPU architecture, list of all connected hardware, interrupts, I/O ports, kernel boot messages, and more.
messages.txt
Contains log messages from the system journal.
rpm.txt
Contains a list of all installed RPM packages, the name, where they are coming from, and their versions.
summary.xml
Contains some information in XML format like distribution, the version, and product specific fragments.
supportconfig.txt
Contains information about the supportconfig
script
itself.
y2log.txt
Contains YaST specific information like specific packages, configuration files, and log files.
Table 36.1, “Comparison of Features and File Names in the TAR Archive” lists all available features and their file names. Further service packs can extend the list, as can plug-ins.
Feature | File name |
---|---|
APPARMOR | security-apparmor.txt |
AUDIT | security-audit.txt |
AUTOFS | fs-autofs.txt |
BOOT | boot.txt |
BTRFS | fs-btrfs.txt |
DAEMONS | systemd.txt |
CIMOM | cimom.txt |
CRASH | crash.txt |
CRON | cron.txt |
DHCP | dhcp.txt |
DISK | fs-diskio.txt |
DNS | dns.txt |
DOCKER | docker.txt |
DRBD | drbd.txt |
ENV | env.txt |
ETC | etc.txt |
HA | ha.txt |
HAPROXY | haproxy.txt |
HISTORY | shell_history.txt |
IB | ib.txt |
IMAN | novell-iman.txt |
ISCSI | fs-iscsi.txt |
LDAP | ldap.txt |
LIVEPATCH | kernel-livepatch.txt |
LVM | lvm.txt |
MEM | memory.txt |
MOD | modules.txt |
MPIO | mpio.txt |
NET | network-*.txt |
NFS | nfs.txt |
NTP | ntp.txt |
NVME | nvme.txt |
OCFS2 | ocfs2.txt |
OFILES | open-files.txt |
print.txt | |
PROC | proc.txt |
SAR | sar.txt |
SLERT | slert.txt |
SLP | slp.txt |
SMT | smt.txt |
SMART | fs-smartmon.txt |
SMB | samba.txt |
SRAID | fs-softraid.txt |
SSH | ssh.txt |
SSSD | sssd.txt |
SYSCONFIG | sysconfig.txt |
SYSFS | sysfs.txt |
TRANSACTIONAL | transactional-update.txt |
TUNED | tuned.txt |
UDEV | udev.txt |
UFILES | fs-files-additional.txt |
UP | updates.txt |
WEB | web.txt |
X | x.txt |
Use the YaST supportconfig
command line utility to submit system
information to the Global Technical Support. When you experience a server
issue and want the support's assistance, you will need to open a service
request first. For details, see
Section 36.2.1, “Creating a Service Request Number”.
The following examples use 12345678901 as a placeholder for your service request number. Replace 12345678901 with the service request number you created in Section 36.2.1, “Creating a Service Request Number”.
The following procedure assumes that you have already created a Supportconfig archive, but have not uploaded it yet. Make sure to have included your contact information in the archive as described in Section 36.2.3, “Creating a Supportconfig Archive with YaST”, Step 4. For instructions on how to generate and submit a Supportconfig archive in one go, see Section 36.2.3, “Creating a Supportconfig Archive with YaST”.
Start YaST and open the
module.Click
.In
specify the path to the existing Supportconfig archive or for it.YaST automatically proposes an upload server. If you want to modify it, refer to Section 36.2.2, “Upload Targets” for details of which upload servers are available.
Proceed with
.Click
.The following procedure assumes that you have already created a Supportconfig archive, but have not uploaded it yet. For instructions on how to generate and submit a Supportconfig archive in one go, see Section 36.2.3, “Creating a Supportconfig Archive with YaST”.
Servers with Internet connectivity:
To use the default upload target, run:
tux >
sudo
supportconfig -ur 12345678901
For the secure upload target, use the following:
tux >
sudo
supportconfig -ar 12345678901
Servers without Internet connectivity
Run the following:
tux >
sudo
supportconfig -r 12345678901
Manually upload the
/var/log/scc_SR12345678901*tbz
archive to one of our FTP servers. Which one to use depends on your
location in the world. For an overview, see
Section 36.2.2, “Upload Targets”.
After the TAR archive arrives in the incoming directory of our FTP server, it becomes automatically attached to your service request.
System reports created with supportconfig
can be analyzed
for known issues to help resolve problems faster. For this purpose,
SUSE Linux Enterprise Desktop provides both an appliance and a command line tool for
Supportconfig Analysis
(SCA). The SCA appliance is a
server-side tool which is non-interactive. The SCA tool
(scatool
provided by the package
sca-server-report) runs on the client-side and is
executed from command line. Both tools analyze Supportconfig archives from
affected servers. The initial server analysis takes place on the SCA
appliance or the workstation on which scatool
is
running. No analysis cycles happen on the production server.
Both the appliance and the command line tool additionally need product-specific patterns that enable them to analyze the Supportconfig output for the associated products. Each pattern is a script that parses and evaluates a Supportconfig archive for one known issue. The patterns are available as RPM packages.
You can also develop your own patterns as briefly described in Section 36.4.3, “Developing Custom Analysis Patterns”.
The SCA command line tool lets you analyze a local machine using both
supportconfig
and the analysis patterns for the specific
product that is installed on the local machine. The tool creates an HTML
report showing its analysis results. For an example, see
Figure 36.1, “HTML Report Generated by SCA Tool”.
The scatool
command is provided by the
sca-server-report package. It is
not installed by default. Additionally, you need the
sca-patterns-base package and any
of the product-specific
sca-patterns-* packages that
matches the product installed on the machine where you want to run the
scatool
command.
Execute the scatool
command either as root
user or
with sudo
. When calling the SCA tool, either
analyze an existing supportconfig
TAR archive or
let it generate and analyze a new archive in one go. The tool also provides
an interactive console with tab completion. It is possible to run
supportconfig
on an external machine and to execute the
subsequent analysis on the local machine.
Find some example commands below:
sudo scatool
-s
Calls supportconfig
and generates a new Supportconfig
archive on the local machine. Analyzes the archive for known issues by
applying the SCA analysis patterns that match the installed product.
Displays the path to the HTML report that is generated from the results
of the analysis. It is usually written to the same directory where the
Supportconfig archive can be found.
sudo scatool
-s
-o
/opt/sca/reports/
Same as sudo scatool
-s
, only that
the HTML report is written to the path specified with
-o
.
sudo scatool
-a
PATH_TO_TARBALL_OR_DIR
Analyzes the specified Supportconfig archive file (or the specified directory to where the Supportconfig archive has been extracted). The generated HTML report is saved in the same location as the Supportconfig archive or directory.
sudo scatool
-a
SLES_SERVER.COMPANY.COM
Establishes an SSH connection to an external server
SLES_SERVER.COMPANY.COM and runs
supportconfig
on the server. The Supportconfig
archive is then copied back to the local machine and is analyzed there.
The generated HTML report is saved to the default
/var/log
directory. (Only the Supportconfig archive
is created on SLES_SERVER.COMPANY.COM).
sudo scatool
-c
Starts the interactive console for scatool
. Press
→| twice to see the available commands.
For further options and information, run sudo scatool -h
or see the scatool
man page.
If you decide to use the SCA appliance for analyzing the Supportconfig archives, configure a dedicated server (or virtual machine) as the SCA appliance server. The SCA appliance server can then be used to analyze Supportconfig archives from all machines in your enterprise running SUSE Linux Enterprise Server or SUSE Linux Enterprise Desktop. You can simply upload Supportconfig archives to the appliance server for analysis. Interaction is not required. In a MariaDB database, the SCA appliance keeps track of all Supportconfig archives that have been analyzed . You can read the SCA reports directly from the appliance Web interface. Alternatively, you can have the appliance send the HTML report to any administrative user via e-mail. For details, see Section 36.4.2.5.4, “Sending SCA Reports via E-Mail”.
To install and set up the SCA appliance in a very fast way from the command line, follow the instructions here. The procedure is intended for experts and focuses on the bare installation and setup commands. For more information, refer to the more detailed description in Section 36.4.2.2, “Prerequisites” to Section 36.4.2.3, “Installation and Basic Setup”.
Web and LAMP Pattern
Web and Scripting Module (you must register the machine to be able to select this module).
root
Privileges Required
All commands in the following procedure must be run as root
.
After the appliance is set up and running, no more manual interaction is required. This way of setting up the appliance is therefore ideal for using cron jobs to create and upload Supportconfig archives.
On the machine on which to install the appliance, log in to a console and execute the following commands:
tux >
sudo
zypper install sca-appliance-* sca-patterns-* vsftpd systemctl enable apache2 systemctl start apache2 systemctl enable vsftpd systemctl start vsftpd yast ftp-server
In YaST FTP Server, select
› › › › to .Execute the following commands:
tux >
sudo
systemctl enable mysql systemctl start mysql mysql_secure_installation setup-sca -f
The mysql_secure_installation will create a MariaDB root
password.
This way of setting up the appliance requires manual interaction when typing the SSH password.
On the machine on which to install the appliance, log in to a console.
Execute the following commands:
tux >
sudo
zypper install sca-appliance-* sca-patterns-* systemctl enable apache2 systemctl start apache2 sudo systemctl enable mysql systemctl start mysql mysql_secure_installation setup-sca
To run an SCA appliance server, you need the following prerequisites:
All sca-appliance-*
packages.
The sca-patterns-base
package.
Additionally, any of the product-specific
sca-patterns-*
for the type of
Supportconfig archives that you want to analyze with the appliance.
Apache
PHP
MariaDB
anonymous FTP server (optional)
As listed in Section 36.4.2.2, “Prerequisites”, the SCA appliance has several dependencies on other packages. Therefore you need do so some preparations before installing and setting up the SCA appliance server:
For Apache and MariaDB, install the Web
and
LAMP
installation patterns.
Set up Apache, MariaDB, and optionally an anonymous FTP server.
Configure Apache and MariaDB to start at boot time:
tux >
sudo
systemctl enable apache2 mysql
Start both services:
tux >
sudo
systemctl start apache2 mysql
Now you can install the SCA appliance and set it up as described in Procedure 36.5, “Installing and Configuring the SCA Appliance”.
After installing the packages, use the setup-sca
script for the basic configuration of the MariaDB administration and
report database that is used by the SCA appliance.
It can be used to configure the following options you have for uploading the Supportconfig archives from your machines to the SCA appliance:
scp
anonymous FTP server
Install the appliance and the SCA base-pattern library:
tux >
sudo
zypper install sca-appliance-* sca-patterns-base
Additionally, install the pattern packages for the types of
Supportconfig archives you want to analyze. For example, if you have
SUSE Linux Enterprise Server 12 and SUSE Linux Enterprise Server 15 servers in your environment, install both the
sca-patterns-sle12
and
sca-patterns-sle15
packages.
To install all available patterns:
tux >
sudo
zypper install sca-patterns-*
For basic setup of the SCA appliance, use the
setup-sca
script. How to call it depends on how you
want to upload the Supportconfig archives to the SCA appliance server:
If you have configured an anonymous FTP server that uses the
/srv/ftp/upload
directory, execute the setup
script with the -f
option. Follow the instructions
on the screen:
tux >
sudo
setup-sca -f
If your FTP server uses another directory than
/srv/ftp/upload
, adjust the following
configuration files first to make them point to the correct
directory: /etc/sca/sdagent.conf
and
/etc/sca/sdbroker.conf
.
If you want to upload Supportconfig files to the
/tmp
directory of the SCA appliance server via
scp
, call the setup script without any parameters.
Follow the instructions on the screen:
tux >
sudo
setup-sca
The setup script runs a few checks regarding its requirements and
configures the needed components. It will prompt you for two passwords:
the MySQL root
password of the MariaDB that you have set up, and a
Web user password with which to log in to the Web interface of the SCA
appliance.
Enter the existing MariaDB root
password. It will allow the SCA
appliance to connect to the MariaDB.
Define a password for the Web user. It will be written to
/srv/www/htdocs/sca/web-config.php
and will be set
as the password for the user
scdiag
. Both user name and
password can be changed at any time later, see
Section 36.4.2.5.1, “Password for the Web Interface”.
After successful installation and setup, the SCA appliance is ready for use, see Section 36.4.2.4, “Using the SCA Appliance”. However, you should modify some options such as changing the password for the Web interface, changing the source for the SCA pattern updates, enabling archiving mode or configuring e-mail notifications. For details on that, see Section 36.4.2.5, “Customizing the SCA Appliance”.
As the reports on the SCA appliance server contain security-relevant information, make sure to protect the data on the SCA appliance server against unauthorized access.
You can upload existing Supportconfig archives to the SCA appliance manually or create new Supportconfig archives and upload them to the SCA appliance in one step. Uploading can be done via FTP or SCP. For both, you need to know the URL where the SCA appliance can be reached. For upload via FTP, an FTP server needs to be configured for the SCA appliance, see Procedure 36.5, “Installing and Configuring the SCA Appliance”.
For creating a Supportconfig archive and uploading it via (anonymous) FTP:
tux >
sudo
supportconfig -U “ftp://SCA-APPLIANCE.COMPANY.COM/upload”
For creating a Supportconfig archive and uploading it via SCP:
tux >
sudo
supportconfig -U “scp://SCA-APPLIANCE.COMPANY.COM/tmp”
You will be prompted for the root
user password of the server
running the SCA appliance.
If you want to manually upload one or multiple archives, copy the
existing archive files (usually located
at/var/log/scc_*.tbz
) to the SCA appliance. As
target, use either the appliance server's /tmp
directory or the /srv/ftp/upload
directory (if FTP
is configured for the SCA appliance server).
SCA reports can be viewed from any machine that has a browser installed and can access the report index page of the SCA appliance.
Start a Web browser and make sure that JavaScript and cookies are enabled.
As a URL, enter the report index page of the SCA appliance.
https://sca-appliance.company.com/sca
If in doubt, ask your system administrator.
You will be prompted for a user name and a password to log in.
After logging in, click the date of the report you want to read.
Click the
category first to expand it.In the
column, click an individual entry. This opens the corresponding article in the SUSE Knowledge base. Read the proposed solution and follow the instructions.If the
column of the shows any additional entries, click them. Read the proposed solution and follow the instructions.Check the SUSE Knowledge base (https://www.suse.com/support/kb/) for results that directly relate to the problem identified by SCA. Work at resolving them.
Check for results that can be addressed proactively to avoid future problems.
The following sections show how to change the password for the Web interface, how to change the source for the SCA pattern updates, how to enable archiving mode, and how to configure e-mail notifications.
The SCA Appliance Web interface requires a user name and password for
logging in. The default user name is scdiag
and the
default password is linux
(if not specified otherwise,
see Procedure 36.5, “Installing and Configuring the SCA Appliance”). Change the default password
to a secure password at the earliest possibility. You can also modify the
user name.
Log in as root
user at the system console of the SCA appliance
server.
Open /srv/www/htdocs/sca/web-config.php
in an
editor.
Change the values of $username
and
$password
as desired.
Save the file and exit.
By default, all sca-patterns-*
packages are updated regularly by a root
cron job that executes the
sdagent-patterns
script nightly, which in turn runs
zypper update sca-patterns-*
. A regular system update
will update all SCA appliance and pattern packages. To update the SCA
appliance and patterns manually, run:
tux >
sudo
zypper update sca-*
The updates are installed from the SUSE Linux Enterprise 15 SP1 update
repository by default. You can change the source for the updates to an
RMT server, if desired. When sdagent-patterns
runs
zypper update sca-patterns-*
, it gets the updates from
the currently configured update channel. If that channel is located on an
RMT server, the packages will be pulled from there.
Log in as root
user at the system console of the SCA appliance
server.
Open /etc/sca/sdagent-patterns.conf
in an editor.
Change the entry
UPDATE_FROM_PATTERN_REPO=1
to
UPDATE_FROM_PATTERN_REPO=0
Save the file and exit. The machine does not require any restart to apply the change.
All Supportconfig archives are deleted from the SCA appliance after they have been analyzed and their results have been stored in the MariaDB database. However, for troubleshooting purposes it can be useful to keep copies of Supportconfig archives from a machine. By default, archiving mode is disabled.
Log in as root
user at the system console of the SCA appliance
server.
Open /etc/sca/sdagent.conf
in an editor.
Change the entry
ARCHIVE_MODE=0
to
ARCHIVE_MODE=1
Save the file and exit. The machine does not require any restart to apply the change.
After having enabled archive mode, the SCA appliance will save the
Supportconfig files to the /var/log/archives/saved
directory, instead of deleting them.
The SCA appliance can e-mail a report HTML file for each Supportconfig
analyzed. This feature is disabled by default. When enabling it, you can
define a list of e-mail addresses to which the reports should be sent.
Define a level of status messages that trigger the sending of reports
(STATUS_NOTIFY_LEVEL
).
STATUS_NOTIFY_LEVEL
#Deactivate sending of HTML reports.
Send only SCA reports that include a CRITICAL.
Send only SCA reports that include a WARNING or CRITICAL.
Send only SCA reports that include a RECOMMEND, WARNING or CRITICAL.
Send SCA reports that include a SUCCESS, RECOMMEND, WARNING or CRITICAL.
Log in as root
user at the system console of the SCA appliance
server.
Open /etc/sca/sdagent.conf
in an editor.
Search for the entry STATUS_NOTIFY_LEVEL
. By
default, it is set to $STATUS_OFF
(e-mail
notifications are disabled).
To enable e-mail notifications, change $STATUS_OFF
to the level of status messages that you want to have e-mail reports
for, for example:
STATUS_NOTIFY_LEVEL=$STATUS_SUCCESS
For details, see Possible Values for STATUS_NOTIFY_LEVEL
.
To define the list of recipients to which the reports should be sent:
Search for the entry EMAIL_REPORT='root'
.
Replace root
with a list of e-mail addresses to
which SCA reports should be sent. The e-mail addresses must be
separated by spaces. For example:
EMAIL_REPORT='tux@my.company.com wilber@your.company.com'
Save the file and exit. The machine does not require any restart to apply the changes. All future SCA reports will be e-mailed to the specified addresses.
To back up and restore the MariaDB database that stores the SCA reports,
use the scadb
command as described
below. scadb
is provided by the package
sca-appliance-broker.
Log in as root
user at the system console of the server running
the SCA appliance.
Put the appliance into maintenance mode by executing:
root #
scadb maint
Start the backup with:
root #
scadb backup
The data is saved to a TAR archive:
sca-backup-*sql.gz
.
If you are using the pattern creation database to develop your own patterns (see Section 36.4.3, “Developing Custom Analysis Patterns”), back up this data, too:
root #
sdpdb backup
The data is saved to a TAR archive:
sdp-backup-*sql.gz
.
Copy the following data to another machine or an external storage medium:
sca-backup-*sql.gz
sdp-backup-*sql.gz
/usr/lib/sca/patterns/local
(only needed if you
have created custom patterns)
Reactivate the SCA appliance with:
root #
scadb reset agents
To restore the database from your backup, proceed as follows:
Log in as root
user at the system console of the server running
the SCA appliance.
Copy the newest sca-backup-*sql.gz
and
sdp-backup-*sql.gz
TAR archives to the SCA
appliance server.
To decompress the files, run:
root #
gzip -d *-backup-*sql.gz
To import the data into the database, execute:
root #
scadb import sca-backup-*sql
If you are using the pattern creation database to create your own patterns, also import the following data with:
root #
sdpdb import sdp-backup-*sql
If you are using custom patterns, also restore
/usr/lib/sca/patterns/local
from your backup data.
Reactivate the SCA appliance with:
root #
scadb reset agents
Update the pattern modules in the database with:
root #
sdagent-patterns -u
The SCA appliance comes with a complete pattern development environment
(the SCA Pattern Database) that enables you to develop your own, custom
patterns. Patterns can be written in any programming language. To make them
available for the Supportconfig analysis process, they need to be saved to
/usr/lib/sca/patterns/local
and to be made executable.
Both the SCA appliance and the SCA tool will then run the custom patterns
against new Supportconfig archives as part of the analysis report. For
detailed instructions on how to create (and test) your own patterns, see
https://www.suse.com/c/blog/sca-pattern-development/.
During the installation, supportconfig
is not available.
However, you can collect log files from YaST by using
save_y2logs
. This command will create a
.tar.xz
archive in the directory
/tmp
.
If issues appear very early during installation, you may be able to gather
information from the log file created by
linuxrc
. linuxrc
is a small command
that runs before YaST starts. This log file is available at
/var/log/linuxrc.log
.
The log files available during the installation are not available in the installed system anymore. Properly save the installation log files while the installer is still running.
An important requirement for every enterprise operating system is the level
of support you receive for your environment. Kernel modules are the most
relevant connector between hardware (“controllers”) and the
operating system. Every kernel module in SUSE Linux Enterprise has a
supported
flag that can take three possible values:
“yes”, thus supported
“external”, thus supported
“” (empty, not set), thus unsupported
The following rules apply:
All modules of a self-recompiled kernel are by default marked as unsupported.
Kernel modules supported by SUSE partners and delivered using
SUSE SolidDriver Program
are marked
“external”.
If the supported
flag is not set, loading this module
will taint the kernel. Tainted kernels are not supported. Unsupported
Kernel modules are included in an extra RPM package
(kernel-FLAVOR-extra
).
That package is only available for SUSE Linux Enterprise Desktop and the SUSE Linux Enterprise Workstation Extension.
Those kernels will not be loaded by default
(FLAVOR=default
|xen
|...).
In addition, these unsupported modules are not available in the installer,
and the
kernel-FLAVOR-extra
package is not part of the SUSE Linux Enterprise media.
Kernel modules not provided under a license compatible to the license of
the Linux kernel will also taint the kernel. For details, see
/usr/src/linux/Documentation/sysctl/kernel.txt
and
the state of /proc/sys/kernel/tainted
.
Linux kernel: The value of
/proc/sys/kernel/unsupported
defaults to
2
on SUSE Linux Enterprise 15 SP1 (do not warn in
syslog when loading unsupported modules
). This default is used
in the installer and in the installed system. See
/usr/src/linux/Documentation/sysctl/kernel.txt
for
more information.
modprobe
: The modprobe
utility for
checking module dependencies and loading modules appropriately checks for
the value of the supported
flag. If the value is
“yes” or “external” the module will be loaded,
otherwise it will not. For information on how to override this behavior,
see Section 36.6.2, “Working with Unsupported Modules”.
SUSE does not generally support the removal of storage modules via
modprobe -r
.
While general supportability is important, situations can occur where loading an unsupported module is required. For example, for testing or debugging purposes, or if your hardware vendor provides a hotfix.
To override the default, edit
/etc/modprobe.d/10-unsupported-modules.conf
and
change the value of the variable
allow_unsupported_modules
to 1
. If
an unsupported module is needed in the initrd, do not forget to run
dracut
-f
to update the initrd.
If you only want to try loading a module once, you can use the
--allow-unsupported-modules
option with
modprobe
. For more information, see the
modprobe
man page.
During installation, unsupported modules may be added through driver
update disks, and they will be loaded. To enforce loading of unsupported
modules during boot and afterward, use the kernel command line option
oem-modules
. While installing and initializing the
suse-module-tools
package, the
kernel flag TAINT_NO_SUPPORT
(/proc/sys/kernel/tainted
) will be evaluated. If the
kernel is already tainted, allow_unsupported_modules
will be enabled. This will prevent unsupported modules from failing in
the system being installed. If no unsupported modules are present during
installation and the other special kernel command line option
(oem-modules=1
) is not used, the default still is to
disallow unsupported modules.
Remember that loading and running unsupported modules will make the kernel and the whole system unsupported by SUSE.
man supportconfig
—The
supportconfig
man page.
man supportconfig.conf
—The man page of the
Supportconfig configuration file.
man scatool
—The scatool
man
page.
man scadb
—The scadb
man page.
man setup-sca
—The setup-sca
man page.
https://mariadb.com/kb/en/—The MariaDB documentation.
https://www.suse.com/c/blog/sca-pattern-development/—Instructions on how to create (and test) your own SCA patterns.
https://www.suse.com/c/blog/basic-server-health-check-supportconfig/—A Basic Server Health Check with Supportconfig.
https://community.microfocus.com/t5/GroupWise-Tips-Information/Create-Your-Own-Supportconfig-Plugin/ta-p/1783289—Create Your Own Supportconfig Plugin.
https://www.suse.com/c/blog/creating-a-central-supportconfig-repository/—Creating a Central Supportconfig Repository.
This chapter describes a range of potential problems and their solutions. Even if your situation is not precisely listed here, there may be one similar enough to offer hints to the solution of your problem.
Linux reports things in a very detailed way. There are several places to look when you encounter problems with your system, most of which are standard to Linux systems in general, and some are relevant to SUSE Linux Enterprise Desktop systems. Most log files can be viewed with YaST ( › ).
YaST offers the possibility to collect all system information needed by the support team. Use
› and select the problem category. When all information is gathered, attach it to your support request.
A list of the most frequently checked log files follows with the description
of their typical purpose. Paths containing ~
refer to
the current user's home directory.
Log File |
Description |
---|---|
|
Messages from the desktop applications currently running. |
|
Log files from AppArmor, see Book “Security and Hardening Guide” for detailed information. |
|
Log file from Audit to track any access to files, directories, or resources of your system, and trace system calls. See Book “Security and Hardening Guide” for detailed information. |
|
Messages from the mail system. |
|
Log file from NetworkManager to collect problems with network connectivity |
|
Directory containing Samba server and client log messages. |
|
All messages from the kernel and system log daemon with the “warning” level or higher. |
|
Binary file containing user login records for the current machine
session. View it with |
|
Various start-up and runtime log files from the X Window System. It is useful for debugging failed X start-ups. |
|
Directory containing YaST's actions and their results. |
|
Log file of Zypper. |
Apart from log files, your machine also supplies you with information about
the running system. See
Table 37.2: System Information With the /proc
File System
/proc
File System #
File |
Description |
---|---|
|
Contains processor information, including its type, make, model, and performance. |
|
Shows which DMA channels are currently being used. |
|
Shows which interrupts are in use, and how many of each have been in use. |
|
Displays the status of I/O (input/output) memory. |
|
Shows which I/O ports are in use at the moment. |
|
Displays memory status. |
|
Displays the individual modules. |
|
Displays devices currently mounted. |
|
Shows the partitioning of all hard disks. |
|
Displays the current version of Linux. |
Apart from the /proc
file system, the Linux kernel
exports information with the sysfs
module, an in-memory
file system. This module represents kernel objects, their attributes and
relationships. For more information about sysfs
, see the
context of udev in Chapter 24, Dynamic Kernel Device Management with udev
.
Table 37.3 contains
an overview of the most common directories under /sys
.
/sys
File System #
File |
Description |
---|---|
|
Contains subdirectories for each block device discovered in the system. Generally, these are mostly disk type devices. |
|
Contains subdirectories for each physical bus type. |
|
Contains subdirectories grouped together as a functional types of devices (like graphics, net, printer, etc.) |
|
Contains the global device hierarchy. |
Linux comes with several tools for system analysis and monitoring. See Book “System Analysis and Tuning Guide”, Chapter 2 “System Monitoring Utilities” for a selection of the most important ones used in system diagnostics.
Each of the following scenarios begins with a header describing the problem followed by a paragraph or two offering suggested solutions, available references for more detailed solutions, and cross-references to other scenarios that are related.
Boot problems are situations when your system does not boot properly (does not boot to the expected target and login screen).
If the hardware is functioning properly, it is possible that the boot loader is corrupted and Linux cannot start on the machine. In this case, it is necessary to repair the boot loader. To do so, you need to start the Rescue System as described in Section 37.5.2, “Using the Rescue System” and follow the instructions in Section 37.5.2.4, “Modifying and Re-installing the Boot Loader”.
Alternatively, you can use the Rescue System to fix the boot loader as follows. Boot your machine from the installation media. In the boot screen, choose
› . Select the disk containing the installed system and kernel with the default kernel options.When the system is booted, start YaST and switch to
› . Make sure that the option is enabled, and click . This fixes the corrupted boot loader by overwriting it, or installs the boot loader if it is missing.Other reasons for the machine not booting may be BIOS-related:
Check your BIOS for references to your hard disk. GRUB 2 may simply not be started if the hard disk itself cannot be found with the current BIOS settings.
Check whether your system's boot order includes the hard disk. If the hard disk option was not enabled, your system may install properly, but fails to boot when access to the hard disk is required.
This behavior typically occurs after a failed kernel upgrade and it is known as a kernel panic because of the type of error on the system console that sometimes can be seen at the final stage of the process. If, in fact, the machine has just been rebooted following a software update, the immediate goal is to reboot it using the old, proven version of the Linux kernel and associated files. This can be done in the GRUB 2 boot loader screen during the boot process as follows:
Reboot the computer using the reset button, or switch it off and on again.
When the GRUB 2 boot screen becomes visible, select the
entry and choose the previous kernel from the menu. The machine will boot using the prior version of the kernel and its associated files.After the boot process has completed, remove the newly installed kernel and, if necessary, set the default boot entry to the old kernel using the YaST Section 14.3, “Configuring the Boot Loader with YaST”. However, doing this is probably not necessary because automated update tools normally modify it for you during the rollback process.
module. For more information refer toReboot.
If this does not fix the problem, boot the computer using the installation media. After the machine has booted, continue with Step 3.
If the machine starts, but does not boot into the graphical login
manager, anticipate problems either with the choice of the default systemd
target or the configuration of the X Window System. To check the current
systemd default target run the command sudo systemctl
get-default
. If the value returned is not
graphical.target
, run the command sudo
systemctl isolate graphical.target
. If the graphical login screen
starts, log in and start › ›
and set the to . From now on the system should boot into the graphical
login screen.
If the graphical login screen does not start even if having booted or
switched to the graphical target, your desktop or X Window software is
probably misconfigured or corrupted. Examine the log files at
/var/log/Xorg.*.log
for detailed messages from the X
server as it attempted to start. If the desktop fails during start, it may
log error messages to the system journal that can be queried with the
command journalctl
(see Chapter 17, journalctl
: Query the systemd
Journal
for more information). If these error messages hint at a configuration
problem in the X server, try to fix these issues. If the graphical system
still does not come up, consider reinstalling the graphical desktop.
If a btrfs
root partition
becomes corrupted, try the following options:
Mount the partition with the -o recovery
option.
If that fails, run btrfs-zero-log
on your root
partition.
If the root partition becomes corrupted, use the parameter
forcefsck on the boot prompt. This passes the option
-f
(force) to the fsck
command.
Login problems occur when your machine does boot to the expected welcome screen or login prompt, but refuses to accept the user name and password, or accepts them but then does not behave properly (fails to start the graphic desktop, produces errors, drops to a command line, etc.).
This usually occurs when the system is configured to use network
authentication or directory services and, for some reason, cannot retrieve
results from its configured servers. The
root
user, as the only local
user, is the only user that can still log in to these machines. The
following are some common reasons a machine appears functional but cannot
process logins correctly:
The network is not working. For further directions on this, turn to Section 37.4, “Network Problems”.
DNS is not working at the moment (which prevents GNOME from working and the system from making validated requests to secure servers). One indication that this is the case is that the machine takes an extremely long time to respond to any action. Find more information about this topic in Section 37.4, “Network Problems”.
If the system is configured to use Kerberos, the system's local time may have drifted past the accepted variance with the Kerberos server time (this is typically 300 seconds). If NTP (network time protocol) is not working properly or local NTP servers are not working, Kerberos authentication ceases to function because it depends on common clock synchronization across the network.
The system's authentication configuration is misconfigured. Check the PAM configuration files involved for any typographical errors or misordering of directives. For additional background information about PAM and the syntax of the configuration files involved, refer to Book “Security and Hardening Guide”, Chapter 3 “Authentication with PAM”.
The home partition is encrypted. Find more information about this topic in Section 37.3.3, “Login to Encrypted Home Partition Fails”.
In all cases that do not involve external network problems, the solution is to reboot the system into single-user mode and repair the configuration before booting again into operating mode and attempting to log in again. To boot into single-user mode:
Reboot the system. The boot screen appears, offering a prompt.
Press Esc to exit the splash screen and get to the GRUB 2 text-based menu.
Press B to enter the GRUB 2 editor.
Add the following parameter to the line containing the kernel parameters:
systemd.unit=rescue.target
Press F10.
Enter the user name and password for
root
.
Make all the necessary changes.
Boot into the full multiuser and network mode by entering
systemctl isolate graphical.target
at the command
line.
This is by far the most common problem users encounter, because there are many reasons this can occur. Depending on whether you use local user management and authentication or network authentication, login failures occur for different reasons.
Local user management can fail for the following reasons:
The user may have entered the wrong password.
The user's home directory containing the desktop configuration files is corrupted or write protected.
There may be problems with the X Window System authenticating this particular user, especially if the user's home directory has been used with another Linux distribution prior to installing the current one.
To locate the reason for a local login failure, proceed as follows:
Check whether the user remembered their password correctly before you start debugging the whole authentication mechanism. If the user may have not have remembered their password correctly, use the YaST User Management module to change the user's password. Pay attention to the Caps Lock key and unlock it, if necessary.
Log in as root
and check the
system journal with journalctl -e
for error messages
of the login process and of PAM.
Try to log in from a console (using Ctrl–Alt–F1). If this is successful, the blame cannot be put on PAM, because it is possible to authenticate this user on this machine. Try to locate any problems with the X Window System or the GNOME desktop. For more information, refer to Section 37.3.4, “Login Successful but GNOME Desktop Fails”.
If the user's home directory has been used with another Linux
distribution, remove the Xauthority
file in the
user's home. Use a console login via Ctrl–Alt–F1 and run rm .Xauthority
as this user. This
should eliminate X authentication problems for this user. Try graphical
login again.
If the desktop could not start because of corrupt configuration files, proceed with Section 37.3.4, “Login Successful but GNOME Desktop Fails”.
In the following, common reasons a network authentication for a particular user may fail on a specific machine are listed:
The user may have entered the wrong password.
The user name exists in the machine's local authentication files and is also provided by a network authentication system, causing conflicts.
The home directory exists but is corrupt or unavailable. Perhaps it is write protected or is on a server that is inaccessible at the moment.
The user does not have permission to log in to that particular host in the authentication system.
The machine has changed host names, for whatever reason, and the user does not have permission to log in to that host.
The machine cannot reach the authentication server or directory server that contains that user's information.
There may be problems with the X Window System authenticating this particular user, especially if the user's home has been used with another Linux distribution prior to installing the current one.
To locate the cause of the login failures with network authentication, proceed as follows:
Check whether the user remembered their password correctly before you start debugging the whole authentication mechanism.
Determine the directory server which the machine relies on for authentication and make sure that it is up and running and properly communicating with the other machines.
Determine that the user's user name and password work on other machines to make sure that their authentication data exists and is properly distributed.
See if another user can log in to the misbehaving machine. If another
user can log in without difficulty or if
root
can log in, log in and
examine the system journal with journalctl -e
>
file. Locate the time stamps that correspond to the login attempts and
determine if PAM has produced any error messages.
Try to log in from a console (using Ctrl–Alt–F1). If this is successful, the problem is not with PAM or the directory server on which the user's home is hosted, because it is possible to authenticate this user on this machine. Try to locate any problems with the X Window System or the GNOME desktop. For more information, refer to Section 37.3.4, “Login Successful but GNOME Desktop Fails”.
If the user's home directory has been used with another Linux
distribution, remove the Xauthority
file in the
user's home. Use a console login via Ctrl–Alt–F1 and run rm .Xauthority
as this user. This
should eliminate X authentication problems for this user. Try graphical
login again.
If the desktop could not start because of corrupt configuration files, proceed with Section 37.3.4, “Login Successful but GNOME Desktop Fails”.
It is recommended to use an encrypted home partition for laptops. If you cannot log in to your laptop, the reason is usually simple: your partition could not be unlocked.
During the boot time, you need to enter the passphrase to unlock your encrypted partition. If you do not enter it, the boot process continues, leaving the partition locked.
To unlock your encrypted partition, proceed as follows:
Switch to the text console with Ctrl–Alt–F1.
Become root
.
Restart the unlocking process again with:
root #
systemctl restart home.mount
Enter your passphrase to unlock your encrypted partition.
Exit the text console and switch back to the login screen with Alt–F7.
Log in as usual.
If this is the case, it is likely that your GNOME configuration files have become corrupted. Some symptoms may include the keyboard failing to work, the screen geometry becoming distorted, or even the screen coming up as a bare gray field. The important distinction is that if another user logs in, the machine works normally. It is then likely that the problem can be fixed relatively quickly by simply moving the user's GNOME configuration directory to a new location, which causes GNOME to initialize a new one. Although the user is forced to reconfigure GNOME, no data is lost.
Switch to a text console by pressing Ctrl–Alt–F1.
Log in with your user name.
Move the user's GNOME configuration directories to a temporary location:
tux >
mv .gconf .gconf-ORIG-RECOVERtux >
mv .gnome2 .gnome2-ORIG-RECOVER
Log out.
Log in again, but do not run any applications.
Recover your individual application configuration data (including the
Evolution e-mail client data) by copying the
~/.gconf-ORIG-RECOVER/apps/
directory back into the
new ~/.gconf
directory as follows:
tux >
cp -a .gconf-ORIG-RECOVER/apps .gconf/
If this causes the login problems, attempt to recover only the critical application data and reconfigure the remainder of the applications.
Many problems of your system may be network-related, even though they do not seem to be at first. For example, the reason for a system not allowing users to log in may be a network problem of some kind. This section introduces a simple checklist you can apply to identify the cause of any network problem encountered.
When checking the network connection of your machine, proceed as follows:
If you use an Ethernet connection, check the hardware first. Make sure that your network cable is properly plugged into your computer and router (or hub, etc.). The control lights next to your Ethernet connector are normally both be active.
If the connection fails, check whether your network cable works with another machine. If it does, your network card causes the failure. If hubs or switches are included in your network setup, they may be faulty, as well.
If using a wireless connection, check whether the wireless link can be established by other machines. If not, contact the wireless network's administrator.
When you have checked your basic network connectivity, try to find out which service is not responding. Gather the address information of all network servers needed in your setup. Either look them up in the appropriate YaST module or ask your system administrator. The following list gives some typical network servers involved in a setup together with the symptoms of an outage.
A broken or malfunctioning name service affects the network's functionality in many ways. If the local machine relies on any network servers for authentication and these servers cannot be found because of name resolution issues, users would not even be able to log in. Machines in the network managed by a broken name server would not be able to “see” each other and communicate.
A malfunctioning or completely broken NTP service could affect Kerberos authentication and X server functionality.
If any application needs data stored in an NFS mounted directory, it
cannot start or function properly if this service was down or
misconfigured. In the worst case scenario, a user's personal desktop
configuration would not come up if their home directory containing the
.gconf
subdirectory could not be found because of
a faulty NFS server.
If any application needs data stored in a directory on a faulty Samba server, it cannot start or function properly.
If your SUSE Linux Enterprise Desktop system relies on a faulty NIS server to provide the user data, users cannot log in to this machine.
If your SUSE Linux Enterprise Desktop system relies on a faulty LDAP server to provide the user data, users cannot log in to this machine.
Authentication will not work and login to any machine fails.
Users cannot print.
Check whether the network servers are running and whether your network setup allows you to establish a connection:
The debugging procedure described below only applies to a simple network server/client setup that does not involve any internal routing. It assumes both server and client are members of the same subnet without the need for additional routing.
Use ping
IP_ADDRESS/HOSTNAME
(replace with the host name or IP address of the server) to check whether
each one of them is up and responding to the network. If this command is
successful, it tells you that the host you were looking for is up and
running and that the name service for your network is configured
correctly.
If ping fails with destination host unreachable
,
either your system or the desired server is not properly configured or
down. Check whether your system is reachable by running
ping
IP address or
YOUR_HOSTNAME from another machine. If you
can reach your machine from another machine, it is the server that is
not running or not configured correctly.
If ping fails with unknown host
, the name service is
not configured correctly or the host name used was incorrect. For
further checks on this matter, refer to
Step 4.b. If
ping still fails, either your network card is not configured correctly
or your network hardware is faulty.
Use host
HOSTNAME to
check whether the host name of the server you are trying to connect to
is properly translated into an IP address and vice versa. If this
command returns the IP address of this host, the name service is up and
running. If the host
command fails, check all network
configuration files relating to name and address resolution on your
host:
/var/run/netconfig/resolv.conf
This file is used to keep track of the name server and domain you are
currently using. It is a symbolic link to
/run/netconfig/resolv.conf
and is usually
automatically adjusted by YaST or DHCP.
Make sure that this file has the following structure and all
network addresses and domain names are correct:
search FULLY_QUALIFIED_DOMAIN_NAME nameserver IPADDRESS_OF_NAMESERVER
This file can contain more than one name server address, but at least one of them must be correct to provide name resolution to your host. If needed, adjust this file using the YaST Network Settings module (Hostname/DNS tab).
If your network connection is handled via DHCP, enable DHCP to change host name and name service information by selecting
(can be set globally for any interface or per interface) and in the YaST Network Settings module (Hostname/DNS tab)./etc/nsswitch.conf
This file tells Linux where to look for name service information. It should look like this:
... hosts: files dns networks: files dns ...
The dns
entry is vital. It tells Linux to use an
external name server. Normally, these entries are automatically
managed by YaST, but it would be prudent to check.
If all the relevant entries on the host are correct, let your system administrator check the DNS server configuration for the correct zone information. If you have made sure that the DNS configuration of your host and the DNS server are correct, proceed with checking the configuration of your network and network device.
If your system cannot establish a connection to a network server and you have excluded name service problems from the list of possible culprits, check the configuration of your network card.
Use the command ip addr show
NETWORK_DEVICE to check whether this device
was properly configured. Make sure that the inet
address
with the netmask
(/MASK
) is configured
correctly. An error in the IP address or a missing bit in your network
mask would render your network configuration unusable. If necessary,
perform this check on the server as well.
If the name service and network hardware are properly configured and
running, but some external network connections still get long time-outs
or fail entirely, use traceroute
FULLY_QUALIFIED_DOMAIN_NAME (executed as
root
) to track the network
route these requests are taking. This command lists any gateway (hop)
that a request from your machine passes on its way to its destination.
It lists the response time of each hop and whether this hop is
reachable. Use a combination of traceroute and ping to track down the
culprit and let the administrators know.
When you have identified the cause of your network trouble, you can resolve it yourself (if the problem is located on your machine) or let the system administrators of your network know about your findings so they can reconfigure the services or repair the necessary systems.
If you have a problem with network connectivity, narrow it down as described in Procedure 37.1, “How to Identify Network Problems”. If NetworkManager seems to be the culprit, proceed as follows to get logs providing hints on why NetworkManager fails:
Open a shell and log in as
root
.
Restart the NetworkManager:
tux >
sudo
systemctl restart NetworkManager
Open a Web page, for example, http://www.opensuse.org as normal user to see, if you can connect.
Collect any information about the state of NetworkManager in
/var/log/NetworkManager
.
For more information about NetworkManager, refer to Chapter 26, Using NetworkManager.
Data problems are when the machine may or may not boot properly but, in either case, it is clear that there is data corruption on the system and that the system needs to be recovered. These situations call for a backup of your critical data, enabling you to recover the system state from before your system failed.
Sometimes you need to perform a backup from an entire partition or even
hard disk. Linux comes with the dd
tool which can create
an exact copy of your disk. Combined with gzip
you save
some space.
Start a Shell as user root
.
Select your source device. Typically this is something like
/dev/sda
(labeled as
SOURCE).
Decide where you want to store your image (labeled as
BACKUP_PATH). It must be different from your
source device. In other words: if you make a backup from
/dev/sda
, your image file must not to be stored
under /dev/sda
.
Run the commands to create a compressed image file:
root #
dd if=/dev/SOURCE | gzip > /BACKUP_PATH/image.gz
Restore the hard disk with the following commands:
root #
gzip -dc /BACKUP_PATH/image.gz | dd of=/dev/SOURCE
If you only need to back up a partition, replace the SOURCE placeholder with your respective partition. In this case, your image file can lie on the same hard disk, but on a different partition.
There are several reasons a system could fail to come up and run properly. A corrupted file system following a system crash, corrupted configuration files, or a corrupted boot loader configuration are the most common ones.
To help you to resolve these situations, SUSE Linux Enterprise Desktop contains a rescue system that you can boot. The rescue system is a small Linux system that can be loaded into a RAM disk and mounted as root file system, allowing you to access your Linux partitions from the outside. Using the rescue system, you can recover or modify any important aspect of your system.
Manipulate any type of configuration file.
Check the file system for defects and start automatic repair processes.
Access the installed system in a “change root” environment.
Check, modify, and re-install the boot loader configuration.
Recover from a badly installed device driver or unusable kernel.
Resize partitions using the parted command. Find more information about this tool at the GNU Parted Web site http://www.gnu.org/software/parted/parted.html.
The rescue system can be loaded from various sources and locations. The simplest option is to boot the rescue system from the original installation medium.
Insert the installation medium into your DVD drive.
Reboot the system.
At the boot screen, press F4 and choose . Then choose from the main menu.
Enter root
at the Rescue:
prompt. A
password is not required.
If your hardware setup does not include a DVD drive, you can boot the rescue
system from a network source. The following example applies to a remote boot
scenario—if using another boot medium, such as a DVD, modify the
info
file accordingly and boot as you would for a
normal installation.
Enter the configuration of your PXE boot setup and add the lines
install=PROTOCOL://INSTSOURCE
and rescue=1
. If you need to start the repair system,
use repair=1
instead. As with a normal installation,
PROTOCOL stands for any of the supported network
protocols (NFS, HTTP, FTP, etc.) and INSTSOURCE
for the path to your network installation source.
Boot the system using “Wake on LAN”, as described in Book “Deployment Guide”, Chapter 13 “Preparing Network Boot Environment”, Section 13.5 “Using Wake-on-LAN for Remote Wakeups”.
Enter root
at the Rescue:
prompt. A
password is not required.
When you have entered the rescue system, you can use the virtual consoles that can be reached with Alt–F1 to Alt–F6.
A shell and other useful utilities, such as the mount program, are
available in the /bin
directory. The
/sbin
directory contains important file and network
utilities for reviewing and repairing the file system. This directory also
contains the most important binaries for system maintenance, such as
fdisk
, mkfs
, mkswap
,
mount
, and shutdown
,
ip
and ss
for maintaining the network.
The directory /usr/bin
contains the vi editor, find,
less, and SSH.
To see the system messages, either use the command dmesg
or view the system log with journalctl
.
As an example for a configuration that might be fixed using the rescue system, imagine you have a broken configuration file that prevents the system from booting properly. You can fix this using the rescue system.
To manipulate a configuration file, proceed as follows:
Start the rescue system using one of the methods described above.
To mount a root file system located under /dev/sda6
to the rescue system, use the following command:
tux >
sudo
mount /dev/sda6 /mnt
All directories of the system are now located under
/mnt
Change the directory to the mounted root file system:
tux >
sudo
cd /mnt
Open the problematic configuration file in the vi editor. Adjust and save the configuration.
Unmount the root file system from the rescue system:
tux >
sudo
umount /mnt
Reboot the machine.
Generally, file systems cannot be repaired on a running system. If you
encounter serious problems, you may not even be able to mount your root file
system and the system boot may end with a “kernel panic”. In
this case, the only way is to repair the system from the outside. The system
contains the utilities to check and repair the btrfs
,
ext2
, ext3
, ext4
,
xfs
, dosfs
, and vfat
file systems. Look for the command
fsck.FILESYSTEM
.
For example, if you need a file system
check for btrfs
, use fsck.btrfs
.
If you need to access the installed system from the rescue system, you need to do this in a change root environment. For example, to modify the boot loader configuration, or to execute a hardware configuration utility.
To set up a change root environment based on the installed system, proceed as follows:
If you are using an LVM setup (refer to Book “Deployment Guide”, Chapter 6 “Expert Partitioner”, Section 6.2 “LVM Configuration” for more general details), import all existing volume groups to be able to find and mount the device(s):
root
vgimport -a
Run lsblk
to check which node corresponds to the root
partition. It is /dev/sda2
in our example:
tux >
lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 149,1G 0 disk
├─sda1 8:1 0 2G 0 part [SWAP]
├─sda2 8:2 0 20G 0 part /
└─sda3 8:3 0 127G 0 part
└─cr_home 254:0 0 127G 0 crypt /home
Mount the root partition from the installed system:
tux >
sudo
mount /dev/sda2 /mnt
Mount /proc
, /dev
, and
/sys
partitions:
tux >
sudo
mount -t proc none /mnt/proctux >
sudo
mount --rbind /dev /mnt/devtux >
sudo
mount --rbind /sys /mnt/sys
Now you can “change root” into the new environment, keeping
the bash
shell:
tux >
chroot /mnt /bin/bash
Finally, mount the remaining partitions from the installed system:
tux >
mount -a
Now you have access to the installed system. Before rebooting the system,
unmount the partitions with umount
-a
and leave the “change root” environment with
exit
.
Although you have full access to the files and applications of the
installed system, there are some limitations. The kernel that is running is
the one that was booted with the rescue system, not with the change root
environment. It only supports essential hardware and it is not possible to
add kernel modules from the installed system unless the kernel versions are
identical. Always check the version of the currently running (rescue)
kernel with uname -r
and then find out if a matching
subdirectory exists in the /lib/modules
directory in
the change root environment. If yes, you can use the installed modules,
otherwise you need to supply their correct versions on other media, such as
a flash disk. Most often the rescue kernel version differs from the
installed one — then you cannot simply access a sound card, for
example. It is also not possible to start a graphical user interface.
Also note that you leave the “change root” environment when you switch the console with Alt–F1 to Alt–F6.
Sometimes a system cannot boot because the boot loader configuration is corrupted. The start-up routines cannot, for example, translate physical drives to the actual locations in the Linux file system without a working boot loader.
To check the boot loader configuration and re-install the boot loader, proceed as follows:
Perform the necessary steps to access the installed system as described in Section 37.5.2.3, “Accessing the Installed System”.
Check that the GRUB 2 boot loader is installed on the system. If not,
install the package grub2
and run
tux >
sudo
grub2-install /dev/sda
Check whether the following files are correctly configured according to the GRUB 2 configuration principles outlined in Chapter 14, The Boot Loader GRUB 2 and apply fixes if necessary.
/etc/default/grub
/boot/grub2/device.map
(optional file, only present
if created manually)
/boot/grub2/grub.cfg
(this file is generated, do
not edit)
/etc/sysconfig/bootloader
Re-install the boot loader using the following command sequence:
tux >
sudo
grub2-mkconfig -o /boot/grub2/grub.cfg
Unmount the partitions, log out from the “change root” environment, and reboot the system:
tux >
umount -a
exit
reboot
A kernel update may introduce a new bug which can impact the operation of your system. For example a driver for a piece of hardware in your system may be faulty, which prevents you from accessing and using it. In this case, revert to the last working kernel (if available on the system) or install the original kernel from the installation media.
To prevent failures to boot after a faulty kernel update, use the kernel
multiversion feature and tell libzypp
which
kernels you want to keep after the update.
For example to always keep the last two kernels and the currently running one, add
multiversion.kernels = latest,latest-1,running
to the /etc/zypp/zypp.conf
file. See
Book “Deployment Guide”, Chapter 18 “Installing Multiple Kernel Versions” for more information.
A similar case is when you need to re-install or update a broken driver for a device not supported by SUSE Linux Enterprise Desktop. For example when a hardware vendor uses a specific device, such as a hardware RAID controller, which needs a binary driver to be recognized by the operating system. The vendor typically releases a Driver Update Disk (DUD) with the fixed or updated version of the required driver.
In both cases you need to access the installed system in the rescue mode and fix the kernel related problem, otherwise the system may fail to boot correctly:
Boot from the SUSE Linux Enterprise Desktop installation media.
If you are recovering after a faulty kernel update, skip this step. If you need to use a driver update disk (DUD), press F6 to load the driver update after the boot menu appears, and choose the path or URL to the driver update and confirm with .
Choose Enter. If you chose to use DUD, you will be asked to specify where the driver update is stored.
from the boot menu and press
Enter root
at the Rescue:
prompt. A
password is not required.
Manually mount the target system and “change root” into the new environment. For more information, see Section 37.5.2.3, “Accessing the Installed System”.
If using DUD, install/re-install/update the faulty device driver package. Always make sure the installed kernel version exactly matches the version of the driver you are installing.
If fixing faulty kernel update installation, you can install the original kernel from the installation media with the following procedure.
Identify your DVD device with hwinfo --cdrom
and
mount it with mount /dev/sr0 /mnt
.
Navigate to the directory where your kernel files are stored on the DVD,
for example cd /mnt/suse/x86_64/
.
Install required kernel-*
,
kernel-*-base
, and
kernel-*-extra
packages of your flavor with the
rpm -i
command.
Update configuration files and reinitialize the boot loader if needed. For more information, see Section 37.5.2.4, “Modifying and Re-installing the Boot Loader”.
Remove any bootable media from the system drive and reboot.
This example network is used across all network-related chapters of the SUSE® Linux Enterprise Desktop documentation.
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