The macOS system must be configured with the SSH daemon ClientAliveInterval option set to 900 or less.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-230764	APPL-11-000051	SV-230764r599842_rule		Medium

Description
If SSH is not being used, this is Not Applicable. The SSH daemon "ClientAliveInterval" option must be set correctly. To check the idle timeout setting for SSH sessions, run the following: /usr/bin/grep ^ClientAliveInterval /etc/ssh/sshd_config If the setting is not "900" or less, this is a finding.

STIG	Date
Apple macOS 11 (Big Sur) Security Technical Implementation Guide	2021-03-29

Details

Check Text ( C-33709r607179_chk )
The SSH daemon "ClientAliveInterval" option must be set correctly. To check the idle timeout setting for SSH sessions, run the following: /usr/bin/grep ^ClientAliveInterval /etc/ssh/sshd_config If the setting is not "900" or less, this is a finding.

Fix Text (F-33682r607180_fix)
To ensure that "ClientAliveInterval" is set correctly, run the following command: /usr/bin/sudo /usr/bin/sed -i.bak 's/.*ClientAliveInterval.*/ClientAliveInterval 900/' /etc/ssh/sshd_config