Import pwnat-0.3nb20131129 as wip/pwnat.

pwnat, by Samy Kamkar, is a tool that allows any client behind a NAT
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.

There is no middle man, no proxy, no 3rd party, no UPnP required, no
spoofing, no DNS tricks. The server does not need to know the client's
IP address before connecting.

More importantly, the client can then connect to any host or port on
any remote host or to a fixed host and port decided by the server.

Simply put, this is a proxy server that works behind a NAT, even when
the client is also behind a NAT.

You can read the paper published in IEEE and presented at the IEEE
P2P'10 Conference here: http://samy.pl/pwnat/pwnat.pdf
+pwnat