NatTraversal
Build NAT to NAT tunnel with a third-party php server.
....
make sure the default stun server 'stunserver.org' available, if not,
change the define 'STUN_HOST' in main.c.
Use 'make A' to build NatTraversalA,
Use 'make B' to build NatTraversalB,
Run each of them on each side of the tunnel you want to create,
need root.
Browse the 'http://YOUR-WEB-URL/nat-status.php' to control and view
status of each side, enjoy.