[Asterisk-Users] How STUN work?

[sgup015 at ec.auckland.ac.nz]

Hi Karl,
I'm suffering with the problem you outlined in (a) regardless of a STUN Server
being used.

Is their anyway around this?

Cheers,
Sahil
Quoting Karl Brose <khb at brose.com>:

> STUN (RFC-3489) is an UNSAF type network protocol (see RFC 3424) that is
> used to discover UDP address and port
>  bindings across network address translators.
>
> (a) Currently Asterisk only supports static configuration of the
> external IP address of a NAT.
> You need to discover it  manually by other means and configure SIP channel.
> This method fails for certain types of NATs that don't  preserve port
> mapping from inside to outside across the
> NAT.  i.e. if you are originating a request from  ipaddress:5060, the
> NAT may map it to anotheraddress:15345
> and this mapping may not be predictable, therefore asterisk cannot send
> proper SIP headers and will fail.
>
> (b) Some ISP providers who use dynamic IPs will force your NAT  router
> to refresh its IP address periodically
> and assign you a different one, at which time it would be nice to
> automatically recognize that without having to
> shut down your Asterisk and restarting.
>
> ShanKutti wrote:
>
> >
> >Hi
> >
> > Can anyone give suggestion why we need STUN while using asterisk behind the
> NAT.
> >
> >Regards
> >Shan.
> >
> >
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