STIGQter: STIG Summary: Canonical Ubuntu 20.04 LTS Security Technical Implementation Guide Version: 1 Release: 1 Benchmark Date: 10 Mar 2021:

The Ubuntu operating system must immediately terminate all network connections associated with SSH traffic at the end of the session or after 10 minutes of inactivity.

DISA Rule

SV-238213r653814_rule

Vulnerability Number

V-238213

Group Title

SRG-OS-000163-GPOS-00072

Rule Version

UBTU-20-010037

Severity

CAT II

CCI(s)

• CCI-001133 - The information system terminates the network connection associated with a communications session at the end of the session or after an organization-defined time period of inactivity.

Weight

10

Fix Recommendation

Configure the Ubuntu operating system to automatically terminate all network connections associated with SSH traffic at the end of a session or after a 10-minute period of inactivity.

Modify or append the following line in the "/etc/ssh/sshd_config" file replacing "[Interval]" with a value of "600" or less:

ClientAliveInterval 600

Restart the SSH daemon for the changes to take effect:

$ sudo systemctl restart sshd.service

Check Contents

Verify that all network connections associated with SSH traffic are automatically terminated at the end of the session or after 10 minutes of inactivity.

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

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

ClientAliveInterval 600

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

Vulnerability Number

V-238213

Documentable

False

Rule Version

UBTU-20-010037

Severity Override Guidance

Verify that all network connections associated with SSH traffic are automatically terminated at the end of the session or after 10 minutes of inactivity.

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

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

ClientAliveInterval 600

If "ClientAliveInterval" does not exist, is not set to 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

5318

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