Concept

A UDP-based protocol that allows two people behind firewalls to establish a direct connection between each other (mediated by a 3rd party server).

Connection Sequence

Here's how a connection is made between person 1 (P1), person 2 (P2) and the server (S).

1. P1 and P2 exchange (via other means -- instant messages for example) a key that uniquely identifies the connection that they want to create
2. P1 and P2 both send this key to the server S
3. ???
4. PROFIT

Resources

• RFC 3489 - STUN - Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NATs)

• NAT Traversal for Multimedia over IP Services (White Paper)

• STUN (Simple Traversal of UDP through NATs (Network Address Translation))