The Photon operating system must configure sshd to disconnect idle Secure Shell (SSH) sessions.

Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on a console or console port that has been left unattended.

At the command line, run the following command:

# sshd -T|&grep -i ClientAliveCountMax

Expected result:

ClientAliveCountMax 0

If the output does not match the expected result, this is a finding.

Navigate to and open:

/etc/ssh/sshd_config

Ensure the "ClientAliveCountMax" line is uncommented and set to the following:

ClientAliveCountMax 0

At the command line, run the following command:

# systemctl restart sshd.service