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The Cloud Linux AlmaLinux OS 9 Security Technical Implementation Guide (V1 R8) has 439 STIG checks. New to STIG checklists? Read What is a STIG checklist?, CKL vs CKLB, and STIG vs SCAP benchmark.
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New to STIG checklists? Read What is a STIG checklist? and CKL vs CKLB.
Note: User namespaces are used primarily for Linux containers. If containers are in use, this requirement is Not Applicable.
Verify AlmaLinux OS 9 disables the use of user namespaces with the following commands:
$ sysctl user.max_user_namespaces
user.max_user_namespaces = 0
If the returned line does not have a value of "0", or a line is not returned, this is a finding.
Check that the configuration files are present to enable this kernel parameter.
$ /usr/lib/systemd/systemd-sysctl --cat-config | egrep -v '^(#|;)' | grep -F user.max_user_namespaces | tail -1
user.max_user_namespaces = 0
If the network parameter "user.max_user_namespaces" is not equal to "0", or nothing is returned, this is a finding.
Configure AlmaLinux OS 9 to disable the use of user namespaces by adding the following line to a file, in the "/etc/sysctl.d" directory:
user.max_user_namespaces = 0
The system configuration files need to be reloaded for the changes to take effect. To reload the contents of the files, run the following command:
$ sudo sysctl --system