Details

If SSHD is enabled then it _MUST_ be configured with an Active Client Alive Maximum Count set to 900 or less.

Setting the Active Client Alive Maximum Count to 900 (second) will log users out after a 15-minute interval of inactivity.

NOTE: /etc/ssh/sshd_config will be automatically modified to its original state following any update or major upgrade to the operating system.

Solution

Run the following bash code

/usr/bin/sed -i.bak 's/.*ClientAliveInterval.*/ClientAliveInterval 900/' /etc/ssh/sshd_config; /bin/launchctl kickstart -k system/com.openssh.sshd
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Supportive Information

The following resource is also helpful.

• https://github.com/usnistgov/macos_security

This security hardening control applies to the following category of controls within NIST 800-53: Access Control, System and Communications Protection.This control applies to the following type of system Unix.

References

• 800-53|AC-12
• 800-53|SC-10
• CCE|CCE-91008-3, CCI|CCI-001133

Source

• Tenable.com/audits