[Freeswitch-dev] bad REGISTER processing

kokoska rokoska kokoska.rokoska at post.cz
Fri Apr 11 03:22:14 EDT 2008

Just for completion of my previous e-mail:

May be I miss something significant and all my thesis are completly 
wrong. If yes, I apologize and ask you for correction of my thoughts :-)
Thank you.

Best regards,


kokoska rokoska napsal(a):
> Thank you very much, Michael, for your answer!
> My comments are included in the e-mail body:
> Michael Jerris napsal(a):
>> The NDLB-connectile-dysfunction is a paramater to explicitly break the  
>> rfc
> My be, but only internaly - i.e. all your public communication could be 
> RFC compliant if you want.
>> and re-write our behavior as if we got a contact of the same  
>> address that we received the packet from.
> Yes, in the same manner as all VoIP TSP (at least all bigger VoIP TSP in 
> Europe) do :-)
>> If it comes from 5060, it  
>> will have 5060 in the contact. 
> And this brakes the RFC and UAC should refuse your 200 OK. There are a 
> lot of broken clients which accepts this but not all of them :-)
>> If you would like to handle nat and  
>> still be rfc compliant, then you need to use a client that follows the  
>> rfc's
> I'm sorry but I don't know what is RFC noncomplient if UAC behind NAT 
> sends private IP in contact. Could you point me to relevant part of some 
> RFC, please? It will be very helpful for me...
>> so you don't have to use non compliant hacks.
> Like I wrote before, I can't remember any real (and not marginal) VoIP 
> telco provider in Europe which doesn't internaly rewrite contact URI in 
> case of UAC behind NAT. Even thou, a lot of them rewrite EVERY contact 
> URI and don't try to detect NAT, because a lot of SOHO routers have 
> SIP-ALG support (god dammed) which makes thing even complicated.
> But there is - IMO - no reason why to rewrite contact URI in 200 OK 
> response to REGISTER request.
> ----------------
> All at all, from my point of view there is a big drawback if I couldn't 
> use FreeSWITCH for UACs behind NAT.
> It forces me to use OpenSER as registrar (what I want to avid to because 
> of performance and harder setup to keep good interoperability) which has 
> no problem with clients behind NAT.
> I believe that improvement in NAT handling could help FreeSWITCH users a 
> lot. Thus I will be glad to help you as much as I can do.
> Please let me know if I can do something handy (other than rewrite FS by 
> myself :-).
> Thanks once more, Michael, for your answer!
> Best regards,
> kokoska.rokoska
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