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 terminate after becoming unresponsive.

DISA Rule

SV-257995r1045053_rule

Vulnerability Number

V-257995

Group Title

SRG-OS-000163-GPOS-00072

Rule Version

RHEL-09-255095

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.

Weight

Fix Recommendation

Note: This setting must be applied in conjunction with RHEL-09-255100 to function correctly.

Configure the SSH server to terminate a user session automatically after the SSH client has become unresponsive.

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

ClientAliveCountMax 1

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

$ sudo systemctl restart sshd.service

Check Contents

Verify the "ClientAliveCountMax" is set to "1" 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*clientalivecountmax'

ClientAliveCountMax 1

If "ClientAliveCountMax" does not exist, is not set to a value of "1" in "/etc/ssh/sshd_config", or is commented out, this is a finding.

Vulnerability Number

V-257995

Documentable

False

Rule Version

RHEL-09-255095

Severity Override Guidance

Check Content Reference

Target Key

5551