Comment by PurplePanda
12 years ago
This is exactly what one of those UDP "weird hole punching tricks" does. Except of course without connections, it not being TCP. nat-traverse (http://m19s28.dyndns.org/iblech/nat-traverse/) works this way as I understand it.
here's an excellent paper on hole punching/nat traversal http://www.brynosaurus.com/pub/net/p2pnat/
For anyone who wants to fiddle as well, I wrote some very simple Ruby code several years ago to do it too: http://www.rubyinside.com/skype-style-firewall-busting-with-...