[pjsip] TCP Transport question...

Klaus Darilion klaus.mailinglists at pernau.at
Fri Mar 21 04:15:07 EDT 2008



Benny Prijono schrieb:
> On 3/19/08, Sasa Coh <sasacoh at gmail.com> wrote:
>> Hello!
>>
>> Yes, it should be error in UAS. Thanks Klaus!
>>
>> Now I have another case:
>> While testing pjSIP's behavior using TCP transport with pjsua, I've
>> encountered another strange situation. If I use STUN server and UDP
>> transport, pjsua sends (as I expected) message SIP REGISTER with correct,
>> STUN resolved addresses in fields "via" and "contact".
>>  On the other hand, if I switch to TCP transport (and use the same STUN
>> server) than pjsua sends message SIP REGISTER with "wrong - IMO" IP
>> addresses (my local-private) in "via" and "contact" fields and not like I
>> would expect with STUN resolved addresses. See log below...
> 
> Yep that's intentional. STUN, as it stands for, applies only to UDP
> transports. For TCP/TLS transport, the only way to get around NAT is
> to use SIP outbound draft, which I plan to implement in the next few
> weeks.

There is also another approach (e.g. which is used by eyebeam/xlite). It 
sends a REGISTER with private IPs. In the response it evaluates the Via 
header and gets the public Ip:port from received and rport parameter. 
Then it deREGISTERs the public contact and reREGISTERs using the learnt 
IP address:port.

regards
klaus



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