[VoIP] STUN

[Martin Harriss]

Richard Lane wrote:
> Hi
> 
> I was wondering if someone could explain stun in regards to how it works 
> and how to implement it on asterisk so i can connect other members to my 
> asterisk server via sip ata's
> 
> Richard

STUN is a method whereby a device inside a firewall can discover the 
"public" IP Address of the external side of the firewall.  A SIP device 
needs to know its public IP address in order to communicate with other 
SIP devices outside the firewall.

I don't believe STUN is necessary if you know your public IP address and 
it never changes (e.g if your ISP has allocated you a static IP address.)

As far as implementation goes, it's a separate piece of software, 
installed, configured and operated outside of Asterisk.  You can get a 
free one for Linus here: http://developer.berlios.de/projects/mystun/

There are also public STUN servers on the internet so you don't 
necessarily have to set one up for yourself.

You can read more about STUN at these places:

http://en.wikipedia.org/wiki/STUN
http://www.voip-info.org/wiki-STUN

(Incidentally, for those that don't know about it, the VOIP wiki at 
www.voip-info.org is a useful resource; there's a lot of Asterisk info 
there, although some of it is a little dated.)

Martin