One more important thing to note: If you really feel you must have NAT, there is IPv6 NAT. Unlike IPv4 NAT, V6 affords enough address space that IPv6 NAT can d

One more important thing to note: If you really feel you must have NAT, there is IPv6 NAT. Unlike IPv4 NAT, V6 affords enough address space that IPv6 NAT can do 1:1 IP:IP mapping between internal and external. This eliminates entire classes of issues around port exhaustion and port remapping and allows P2P applications to work fine. P2P NAT traversal with simple 1:1 NAT has a nearly 100% success rate on the first attempt.