STUN - Simple Traversal of UDP Through Network Address Translators
Jonathan M. Rosenberg, Rohan Mahy, Christian Huitema, Joel Weinberger · 2003
Simple Traversal of UDP Through NATs (STUN) is a lightweight protocol that allows applications to discover the presence and types of Network Address Translators (NATs) and firewalls between them and the public Internet. It also provides the ability for applications to determine the public IP addresses allocated to them by the NAT. STUN works with many existing NATs, and does not require any special behavior from them. As a result, it allows a wide variety of applications to work through existing NAT infrastructure.