The Photon operating system must configure Secure Shell (SSH) to restrict AllowTcpForwarding.

While enabling TCP tunnels is a valuable function of sshd, this feature is not appropriate for use on single purpose appliances.

At the command line, run the following command to verify the running configuration of sshd:

# sshd -T|&grep -i AllowTcpForwarding

Example result:

allowtcpforwarding no

If "AllowTcpForwarding" is not set to "no", this is a finding.

Navigate to and open:

/etc/ssh/sshd_config

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

AllowTcpForwarding no

At the command line, run the following command:

# systemctl restart sshd.service