Verify the system does not have unauthorized IP tunnels configured. Check to see if "libreswan" is installed with the following command: # yum list installed libreswan libreswan.x86-64 3.20-5.el7_4 If "libreswan" is installed, check to see if the "IPsec" service is active with the following command: # systemctl status ipsec ipsec.service - Internet Key Exchange (IKE) Protocol Daemon for IPsec Loaded: loaded (/usr/lib/systemd/system/ipsec.service; disabled) Active: inactive (dead) If the "IPsec" service is active, check to see if any tunnels are configured in "/etc/ipsec.conf" and "/etc/ipsec.d/" with the following commands: # grep -iw conn /etc/ipsec.conf /etc/ipsec.d/*.conf If there are indications that a "conn" parameter is configured for a tunnel, ask the System Administrator if the tunnel is documented with the ISSO. If "libreswan" is installed, "IPsec" is active, and an undocumented tunnel is active, this is a finding.