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NAT and Stateful firewalling are commonly bundled together (especially on home systems) but I would not go so far as to say “NAT has a stateful firewall”- I he

• blibble 3y ago
  > but I would not go so far as to say “NAT has a stateful firewall”- > I hear such takes all the time and its really frustrating maybe you'd be less frustrated if you understood what people were saying, because I didn't say that AWS already do 1:1 NAT and there's additionally a stateful firewall, which necessitates connection state tracking adding the extra few bytes to do port translation shouldn't vastly increase the memory required > incidentally it is usually programmers who think they understand everything about networks because they know how tcp operates. from someone who has written a commercial packet filter: in terms of complexity, TCP blows the preceding layers of the stack out of the water
• lxgr 3y ago
  In almost all NAT implementations, public-side ports are dynamically assigned, which implies that inbound connections aren't possible (unless port forwarding is explicitly configured). Is that really conceptually so different from a stateful firewall allowing inbound packets only for established connections/flows? "NATs are good because otherwise people wouldn't have any firewalls" is a tired take, yes, but I don't see the point being needlessly pedantic about the semantics of NAT vs. stateful firewalls when in this case, the effect is the same: No inbound packets without prior outbound packets (or a connection establishment for TCP).