Tuesday, April 17, 2007

What is STUN Server For SIP Phone ?

STUN (Simple Traversal of UDP through NATs (Network Address Translation)) is a protocol for assisting devices behind a NAT firewall or router with their packet routing.

Note: The STUN RFC states: This protocol is not a cure-all for the problems associated with NAT.


* STUN enables a device to find out its public IP address and the type of NAT service its sitting behind.
* STUN operates on TCP and UDP port 3478.
* STUN is not widely supported by VOIP devices yet.
* STUN may use DNS SRV records to find STUN servers attached to a domain. The service name is _stun._udp or _stun._tcp

Definitions (from the RFC)

* STUN Client: A STUN client (also just referred to as a client) is an entity that generates STUN requests. A STUN client can execute on an end system, such as a user's PC, or can run in a network element, such as a conferencing server.
* STUN Server: A STUN Server (also just referred to as a server) is an entity that receives STUN requests, and sends STUN responses. STUN servers are generally attached to the public Internet.

http://www.voip-info.org/wiki/view/STUN

http://www.vovida.org/applications/downloads/stun/

No comments: