To disable RHEL user namespaces

Purpose

Current and future RHEL OS vulnerabilities may be mitigated by disabling namespaces for RHEL users.

Note: Disabling RHEL namespaces is described in a STIG recommendation.

For greater OS security, perform the following steps to disable the use of namespaces by any RHEL user on any NSP station.

Steps
 
1 

Log in as the root user on the station that hosts the OS.

2 

Open a console window.

3 

Enter the following to display the current namespace setting:

# cat /proc/sys/user/max_user_namespaces ↵

A numeric value is displayed.

4 

RHEL namespaces are enabled if the value is greater than zero.

If RHEL namespaces are enabled, perform the following steps.

  1. Enter the following:

    # echo user.max_user_namespaces=0 >/etc/sysctl.d/97-nsp-rhel-oem.conf ↵

  2. Enter the following:

    # cat /etc/sysctl.d/97-nsp-rhel-oem.conf ↵

    The /etc/sysctl.d/97-nsp-rhel-oem.conf file content is listed.

  3. If the file content is anything other than the following, return to substep 1 to correct any input error and recreate the file.

    user.max_user_namespaces=0

  4. Enter the following:

    # sudo sysctl --system ↵

    Namespace usage is disabled.

5 

Enter the following to verify that namespaces are disabled:

# cat /proc/sys/user/max_user_namespaces ↵

A numeric value is displayed.

6 

If the value is not 0, contact technical support for assistance.

7 

Close the console window.

End of steps