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ContentsContents
Security and Hardening Guide
  1. Preface
  2. 1 Security and confidentiality
  3. 2 Common Criteria
  4. I Authentication
    1. 3 Authentication with PAM
    2. 4 Using NIS
    3. 5 Setting up authentication clients using YaST
    4. 6 LDAP with 389 Directory Server
    5. 7 Network authentication with Kerberos
    6. 8 Active Directory support
    7. 9 Setting up a freeRADIUS server
  5. II Local security
    1. 10 Physical security
    2. 11 Software management
    3. 12 File management
    4. 13 Encrypting partitions and files
    5. 14 Storage encryption for hosted applications with cryptctl
    6. 15 User management
    7. 16 Restricting cron and at
    8. 17 Spectre/Meltdown checker
    9. 18 Configuring security settings with YaST
    10. 19 Authorization with PolKit
    11. 20 Access control lists in Linux
    12. 21 Certificate store
    13. 22 Intrusion detection with AIDE
  6. III Network security
    1. 23 X Window System and X authentication
    2. 24 SSH: secure network operations
    3. 25 Masquerading and firewalls
    4. 26 Configuring a VPN server
    5. 27 Managing a PKI with XCA, X certificate and key manager
    6. 28 Improving network security with sysctl variables
    7. 29 Enabling FIPS 140-2
  7. IV Confining privileges with AppArmor
    1. 30 Introducing AppArmor
    2. 31 Getting started
    3. 32 Immunizing programs
    4. 33 Profile components and syntax
    5. 34 AppArmor profile repositories
    6. 35 Building and managing profiles with YaST
    7. 36 Building profiles from the command line
    8. 37 Profiling your Web applications using ChangeHat
    9. 38 Confining users with pam_apparmor
    10. 39 Managing profiled applications
    11. 40 Support
    12. 41 AppArmor glossary
  8. V SELinux
    1. 42 Configuring SELinux
  9. VI The Linux Audit Framework
    1. 43 Understanding Linux audit
    2. 44 Setting up the Linux audit framework
    3. 45 Introducing an audit rule set
    4. 46 Useful resources
  10. A Achieving PCI DSS compliance
  11. B GNU licenses
Navigation
Applies to SUSE Linux Enterprise Server 15 SP3

18 Configuring security settings with YaST

The YaST module Security Center provides a central control panel for configuring security-related settings for SUSE Linux Enterprise Server. Use it to configure security aspects such as settings for the login procedure and for password creation, for boot permissions, user creation, or for default file permissions. Launch it from the YaST control center with Security and Users › Security Center. The Security Center dialog opens to the Security Overview, with additional configuration dialogs in the left and right panes.

18.1 Security overview

The Security Overview displays a comprehensive list of the most important security settings for your system. The security status of each entry in the list is clearly visible. A green check mark indicates a secure setting while a red cross indicates an entry as being insecure. Click Help to open an overview of the setting and information on how to make it secure. To change a setting, click the corresponding link in the Status column. Depending on the setting, the following entries are available:

Enabled/Disabled

Click this entry to toggle the status of the setting to either enabled or disabled.

Configure

Click this entry to launch another YaST module for configuration. You will return to the Security Overview when leaving the module.

Unknown

A setting's status is set to unknown when the associated service is not installed. Such a setting does not represent a potential security risk.

YaST security center and hardening: security overview
Figure 18.1: YaST security center and hardening: security overview

18.2 Predefined security configurations

SUSE Linux Enterprise Server includes three Predefined Security Configurations. These configurations affect all the settings available in the Security Center module. Click Predefined Security Configurations in the left pane to see the predefined configurations. Click the one you want to apply, then the module closes. If you wish to modify the predefined settings, re-open the Security Center module, click Predefined Security Configurations, then click Custom Settings in the right pane. Any changes you make are applied to your selected predefined configuration.

Workstation

A configuration for a workstation with any kind of network connection (including a connection to the Internet).

Roaming device

This setting is designed for a laptop or tablet that connects to different networks.

Network server

Security settings designed for a machine providing network services such as a Web server, file server, name server, etc. This set provides the most secure configuration of the predefined settings.

Custom settings

Select Custom Settings to modify any of the three predefined configurations after they have been applied.

18.3 Password settings

Passwords that are easy to guess are a major security issue. The Password Settings dialog provides the means to ensure that only secure passwords can be used.

Check new passwords

By activating this option, a warning will be issued if new passwords appear in a dictionary, or if they are proper names (proper nouns).

Minimum acceptable password length

If the user chooses a password with a length shorter than specified here, a warning will be issued.

Number of passwords to remember

When password expiration is activated (via Password Age), this setting stores the given number of a user's previous passwords, preventing their reuse.

Password encryption method

Choose a password encryption algorithm. Normally there is no need to change the default (Blowfish).

Password age

Activate password expiration by specifying a minimum and a maximum time limit (in days). By setting the minimum age to a value greater than 0 days, you can prevent users from immediately changing their passwords again (and in doing so circumventing the password expiration). Use the values 0 and 99999 to deactivate password expiration.

Days before password expires warning

When a password expires, the user receives a warning in advance. Specify the number of days prior to the expiration date that the warning should be issued.

18.4 Boot settings

Configure which users can shut down the machine via the graphical login manager in this dialog. You can also specify how CtrlAltDel will be interpreted and who can hibernate the system.

18.5 Login settings

This dialog lets you configure security-related login settings:

Delay after incorrect login attempt

To make it difficult to guess a user's password by repeatedly logging in, it is recommended to delay the display of the login prompt that follows an incorrect login. Specify the value in seconds. Make sure that users who have mistyped their passwords do not need to wait too long.

Allow remote graphical login

When checked, the graphical login manager (GDM) can be accessed from the network. This is a potential security risk.

18.6 User addition

Set minimum and maximum values for user and group IDs. These default settings would rarely need to be changed.

18.7 Miscellaneous settings

Other security settings that do not fit the above-mentioned categories are listed here:

File permissions

SUSE Linux Enterprise Server comes with three predefined sets of file permissions for system files. These permission sets define whether a regular user can read log files or start certain programs. Easy file permissions are suitable for stand-alone machines. These settings allow regular users to, for example, read most system files. See the file /etc/permissions.easy for the complete configuration. The Secure file permissions are designed for multiuser machines with network access. A thorough explanation of these settings can be found in /etc/permissions.secure. The Paranoid settings are the most restrictive ones and should be used with care. See /etc/permissions.paranoid for more information.

User launching updatedb

The program updatedb scans the system and creates a database of all files, which can be queried with the command locate. When updatedb is run as user nobody, only world-readable files will be added to the database. When run as user root, almost all files (except the ones root is not allowed to read) will be added.

Enable magic SysRq keys

The magic SysRq key is a key combination that enables you to have some control over the system even when it has crashed. The complete documentation can be found at https://www.kernel.org/doc/html/latest/admin-guide/sysrq.html.

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