pwnat NAT to NAT client-server communication. Someone might find it useful.
From the host site: pwnat, pronounced "poe-nat", is a tool that allows any number of clients behind NATs to communicate with a server behind a separate NAT with *no* port forwarding and *no* DMZ setup on any routers in order to directly communicate with each other. The server does not need to know anything about the clients trying to connect.
Simply put, this is a proxy server that works behind a NAT, even when the client is behind a NAT, without any 3rd party.
pwnat - NAT to NAT client-server communication
If anyone wants to go ahead and install it (before and if it gets into the repo)(also bear in mind if you do you are on your won for support, problems etc.) then it is a simply matter of download unpack and run the program.
# wget http://samy.pl/pwnat/pwnat-0.2-beta.tgz
# tar -xvf pwnnat*