Testing NAT types (was: Re: [Serusers] Re: RESOLVED - nathelper / calling UAs behind symmetric NATs)

[Thilo Salmon]

On Tue, 2004-01-06 at 01:39, Jan Janak wrote:
> Well, if the UAs use STUN properly, that means they use STUN only when
> they detect a NAT that can be traversed with STUN, then it should work.
> 
> STUN will make the messages to look like they were coming from a UA in
> the public internet and thus the nathelper will not force the RTP proxy.
> 
> UAs behind symmetric NAT should not use STUN-obtained IP addresses (because 
> it would be useless anyway) and send private IP addresses. In this case the
> nathelper module will detect that the UA is behind a NAT and force RTP
> proxy.

You are right. I was only looking at the call-id header field. The
Grandstream UAs I was testing with (firmware 1.0.3.81 and 1.0.4.26) used
RFC 1918 addresses in that field no matter what type of NAT they were
behind. They fix the contact header field, though, _unless_ you they are
behind a symmetric NAT.

Thanks for pointing this out to me.

Thilo