TOSS 5 must enable the Pluggable Authentication Module (PAM) interface for SSHD.

When "UsePAM" is set to "yes", PAM runs through account and session types properly. This is important when restricted access to services based off of IP, time, or other factors of the account are needed. Additionally, this ensures users can inherit certain environment variables on login or disallow access to the server.

Verify the TOSS 5 SSHD is configured to allow for the "UsePAM" interface using the following command:

$ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH '^\s*usepam'

UsePAM yes

If the "UsePAM" keyword is set to "no", is missing, or is commented out, this is a finding.

Configure the TOSS 5 SSHD to use the "UsePAM" interface, by adding or modifying the following line in "/etc/ssh/sshd_config":

UsePAM yes

Restart the SSH daemon for the settings to take effect:

$ sudo systemctl restart sshd.service