"PAT" is not doing any firewalling either. (It does rely on state tracking, which it shares in common with stateful firewalls, but you could run a LAN with eit

"PAT" is not doing any firewalling either. (It does rely on state tracking, which it shares in common with stateful firewalls, but you could run a LAN with either a stateless firewall or no firewall if you really wanted to meet the "nothing in common with a firewall" requirement.)