[OpenSIPS-Users] INVITE not forwarded, call fails

lorenzo asymmetric at autistici.org
Mon Jan 25 19:39:12 CET 2010

On 25/01/10 12:08, Bogdan-Andrei Iancu wrote:
> Hi Lorenzo,
> When comes to NAT traversal, you can do it in two ways:
> 1) on the client (UAC) side - the client is doing the signalling in such 
> a way that the server "sees" the traffic as coming from a public IP. 
> This is actually STUN approach -> the server has 0 capabilities in 
> handling NAT.
> 2)  on the server side - the client has 0 capabilities in handling NAT 
> traversal and the whole task must be done by server. In this case you 
> need to configure opensips to do the nat traversal - to correct both 
> signalling and RTP for coping with NAt.
> My understanding is you tried the first approach, but it fails due poor 
> STUN/NAT working. So, you what to move into 2), right ? IF so, take a 
> look at the nathelper module.

Hi Bogdan!

i think there's a third case, which is when a client does make use of
STUN, but is behind a symmetric NAT.

since the UAC may not be aware of that, the UAS should try and fix the
situation by fixing the contact header, after checking it's different
from the address in the ip header of course :)

i think this is the case i'm in.

anyway, thanks for the tip, i'll take a deeper look at the nathelper module.

> Regards,
> Bogdan


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