Big Sur - Configure SSH ServerAliveInterval option set to 900 or less

Information

SSH _MUST_ be configured with an Active Server Alive Maximum Count set to 900 or less.

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

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

Solution

[source,bash]
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/usr/bin/grep -q '^ServerAliveInterval' /etc/ssh/ssh_config && /usr/bin/sed -i.bak 's/.*ServerAliveInterval.*/ServerAliveInterval 900/' /etc/ssh/ssh_config || /bin/echo 'ServerAliveInterval 900' >> /etc/ssh/ssh_config
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See Also

https://github.com/usnistgov/macos_security

Item Details

Category: ACCESS CONTROL, SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|AC-12, 800-53|SC-10, CCE|CCE-85381-2

Plugin: Unix

Control ID: 706c4c119a1849df28338b21a6cb770b572de93b05c1023c00ebce1cd8441c0f