Actually my point was that with protocols like GRE it difficult to NAT more than one stream through an IP address. Also even if you do work that out (people hav

Actually my point was that with protocols like GRE it difficult to NAT more than one stream through an IP address. Also even if you do work that out (people have it seems) you need to work it out for every protocol which is not how the layers of TCP/IP were supposed to work.