Okay, but unless you've poked a hole through NAT (and if you have, presumably you know what you're doing), what are those incoming connections going to connect to?
If there's nothing to connect to, is there really an incoming connection?
If there's nothing to connect to, is there really an incoming connection?
You aren't in control of the contents of inbound packets, and NAT won't filter them to enforce anything about the destination IPs in them either.