STIGQter: STIG Summary: Tri-Lab Operating System Stack (TOSS) 4 Security Technical Implementation Guide Version: 2 Release: 6 Benchmark Date: 01 Jul 2026:

TOSS must be configured so that all network connections associated with SSH traffic are terminated at the end of the session or after 10 minutes of inactivity, except to fulfill documented and validated mission requirements.

DISA Rule

SV-253083r986603_rule

Vulnerability Number

V-253083

Group Title

SRG-OS-000126-GPOS-00066

Rule Version

TOSS-04-040290

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

10

Fix Recommendation

Configure TOSS to automatically terminate all network connections associated with SSH traffic at the end of a session or after 10 minutes of inactivity, or as long as documented with the information system security officer (ISSO) as an operational requirement.

Modify or append the following lines in the "/etc/ssh/sshd_config" file to have a product value of "600" or less:

ClientAliveInterval 600
ClientAliveCountMax 1

In order for the changes to take effect, the SSH daemon must be restarted.

$ sudo systemctl restart sshd.service

Check Contents

Verify all network connections associated with SSH traffic are automatically terminated at the end of the session or after 10 minutes of inactivity, or as long as documented with the information system security officer (ISSO) as an operational requirement.

Check that the "ClientAliveInterval" variable is set to a value of "600" or less and that the "ClientAliveCountMax" is set to "1" by performing the following command:

$ sudo grep -i clientalive /etc/ssh/sshd_config

ClientAliveInterval 600
ClientAliveCountMax 1

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

Vulnerability Number

V-253083

Documentable

False

Rule Version

TOSS-04-040290

Severity Override Guidance

Verify all network connections associated with SSH traffic are automatically terminated at the end of the session or after 10 minutes of inactivity, or as long as documented with the information system security officer (ISSO) as an operational requirement.

Check that the "ClientAliveInterval" variable is set to a value of "600" or less and that the "ClientAliveCountMax" is set to "1" by performing the following command:

$ sudo grep -i clientalive /etc/ssh/sshd_config

ClientAliveInterval 600
ClientAliveCountMax 1

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

Check Content Reference

M

Target Key

5469