FWIW, I managed to get two clients, each behind its own HTTP proxy, connect to each other using symmetrical TCP open. Not browsers, and with the help of a coord

FWIW, I managed to get two clients, each behind its own HTTP proxy, connect to each other using symmetrical TCP open. Not browsers, and with the help of a coordinating server, but the clients did end up with a direct connection between themselves. People tend to think it is hard, because no one does it, and no one does it, because everyone thinks it's hard. Catch 22. Just try it, damn it. It's trivial :)