STIGQter: STIG Summary: Canonical Ubuntu 18.04 LTS Security Technical Implementation Guide Version: 2 Release: 3 Benchmark Date: 23 Apr 2021:

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

DISA Rule

SV-219311r610963_rule

Vulnerability Number

V-219311

Group Title

SRG-OS-000163-GPOS-00072

Rule Version

UBTU-18-010416

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.
• CCI-002361 - The information system automatically terminates a user session after organization-defined conditions or trigger events requiring session disconnect.

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

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

# 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.

Check that 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-219311

Documentable

False

Rule Version

UBTU-18-010416

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.

Check that 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

4055

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