[OpenSIPS-Users] [nat_traversal] Replacement of bflag(NAT_CALLED) ?

Klaus Darilion klaus.mailinglists at pernau.at
Wed Nov 12 12:20:34 CET 2008

Dan Pascu schrieb:
> On Wednesday 12 November 2008, Klaus Darilion wrote:
>> Dan Pascu schrieb:
>>> ...
>>> As a side note, nat_traversal itself doesn't need that mechanism
>>> because it can figure out itself if a destination device is behind
>>> NAT and it needs to keep it alive during a call. So you only call
>>> nat_traversal() when you have a caller behind NAT that you want to
>>> keep reachable (for either REGISTER, SUBSCRIBE or INVITE sessions).
>> Hi Dan!
>> I think for testing if the callee is behind NAT, the nattraversal
>> module can not help me, I still have to use the nat_bflag - is this
>> correct?
> Yes. For your own purposes you need to use a bflag per contact.
> What I meant, is that for its internal purposes when it comes to keepalive 
> endpoints, the nat_traversal module does figure out automatically without 
> you doing anything, if the destination of an INVITE needs to be kept 
> alive during the call.

I still do not understand. The callee has to be registered - otherwise 
it is not reachable at all. Thus, keep-alive for the callee will be done 
once it registers based on nat tests during REGISTER. Thus, when calling 
the callee, the session is implicitly keep-alive'd by the the keep-alive 
  triggered by registration. What do I miss?


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