Comment by Dagger2
1 month ago
It might be dropped by a firewall, but not by NAT.
IP packets have a "destination IP" field in the header. The router knows where to forward packets because it reads that IP out of the header.
1 month ago
It might be dropped by a firewall, but not by NAT.
IP packets have a "destination IP" field in the header. The router knows where to forward packets because it reads that IP out of the header.
Sure, but the Internet will not route packets going to RFC1918 addresses. So, if you're using an RFC1918 address on the LAN side of the router like every sane admin, packets that actually arrive to the router from the Internet with an IP address other than the router's own IP address will get dropped. And those that arrive at the router with the router's own IP address and a port that doesn't correspond to either an open connection or an explicit port forwarding rule will also get refused.
This is all behavior that happens even with no firewall whatsoever.
So? How is any of that relevant?
Because this is exactly what the GP was claiming, and you denied: even without a firewall, packets that don't correspond to an open connection will get dropped by a NAT, even without a firewall. Sure, maybe "dropped" is wrong, as the NAT box will probably instead send a RST packet, but this is almost entirely irrelevant.
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Because that is the most common NAT configuration for 99.99% of residential users. Anything else is academic discussion.
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