You have a mix of accurate mix with not so much here.
> I've had hosts with internal IPv4 addresses attacked on web ports because they were behind a (reverse proxy) load balancer for serving traffic: the fact that they had a 10/8 and were behind a NAT did not protect them from attack.
You explicitly set up a NAT bypass (reverse proxy) and then claim NAT didn't protect them. If I am an external attacker coming in towards a single public IP where the backside hasn't set up UPNP/Port Forwarding/STUN/Reverse Proxy, NAT does exactly what the previous poster said. It drops packets because the 'destination' is the router itself in the packet. It has no where else to go, it has literally reached its destination.
A stateful firewall is in no way necessary for this functionality to exist. Even UDP stateless packets cannot bypass the NAT because there if there is no table tracking the conversation from the POV of the inside->out initiating the conversation because the router would have zero idea which interior host to forward the packet to and no reason to do so.
> I've had hosts with internal IPv4 addresses attacked on web ports because they were behind a (reverse proxy) load balancer for serving traffic: the fact that they had a 10/8 and were behind a NAT did not protect them from attack.
You explicitly set up a NAT bypass (reverse proxy) and then claim NAT didn't protect them. If I am an external attacker coming in towards a single public IP where the backside hasn't set up UPNP/Port Forwarding/STUN/Reverse Proxy, NAT does exactly what the previous poster said. It drops packets because the 'destination' is the router itself in the packet. It has no where else to go, it has literally reached its destination.
A stateful firewall is in no way necessary for this functionality to exist. Even UDP stateless packets cannot bypass the NAT because there if there is no table tracking the conversation from the POV of the inside->out initiating the conversation because the router would have zero idea which interior host to forward the packet to and no reason to do so.