STIGQter: STIG Summary: Red Hat Enterprise Linux 9 Security Technical Implementation Guide Version: 2 Release: 9 Benchmark Date: 01 Jul 2026:

RHEL 9 must be configured so that all network connections associated with SSH traffic are terminated after 10 minutes of becoming unresponsive.

DISA Rule

SV-257996r1134915_rule

Vulnerability Number

V-257996

Group Title

SRG-OS-000126-GPOS-00066

Rule Version

RHEL-09-255100

Severity

CAT II

CCI(s)

• CCI-001133 - Terminate the network connection associated with a communications session at the end of the session or after an organization-defined time period of inactivity.
• CCI-002361 - Automatically terminate a user session after organization-defined conditions or trigger events requiring session disconnect.
• CCI-002891 - Verify session and network connection termination after the completion of nonlocal maintenance and diagnostic sessions.

Weight

10

Fix Recommendation

Note: This setting must be applied in conjunction with RHEL-09-255095 to function correctly.

Configure the SSH server to terminate a user session automatically after the SSH client has been unresponsive for 10 minutes.

Modify or append the following lines in the "/etc/ssh/sshd_config" or in a file in "/etc/ssh/sshd_config.d":

ClientAliveInterval 600

For the changes to take effect, the SSH daemon must be restarted.

$ sudo systemctl restart sshd.service

Check Contents

Verify the "ClientAliveInterval" variable is set to a value of "600" or less by performing the following command:

$ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH '^\s*clientaliveinterval'

/etc/ssh/sshd_config.d/ClientAliveInterval.conf:ClientAliveInterval 600

Verify the runtime value of "ClientAliveInterval" with the following command:

$ sudo sshd -T | grep -i clientaliveinterval

clientaliveinterval 600

If "ClientAliveInterval" does not exist, does not have a value of "600" or less in "/etc/ssh/sshd_config", or is commented out, this is a finding.

Vulnerability Number

V-257996

Documentable

False

Rule Version

RHEL-09-255100

Severity Override Guidance

Verify the "ClientAliveInterval" variable is set to a value of "600" or less by performing the following command:

$ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH '^\s*clientaliveinterval'

/etc/ssh/sshd_config.d/ClientAliveInterval.conf:ClientAliveInterval 600

Verify the runtime value of "ClientAliveInterval" with the following command:

$ sudo sshd -T | grep -i clientaliveinterval

clientaliveinterval 600

If "ClientAliveInterval" does not exist, does not have a value of "600" or less in "/etc/ssh/sshd_config", or is commented out, this is a finding.

Check Content Reference

M

Target Key

5551