[SR-Users] NAT Traversal

Daniel-Constantin Mierla miconda at gmail.com
Wed Mar 2 09:30:47 CET 2011


Hello,

one option might be a bad ALG implementation in the router.

Can you send a full ngrep of such case? You can obfuscate the IP 
addresses, use different ones for each point in the network and leave 
the ports. Seeing SIP headers and SDP can indicate the presence of an 
ALG or something broken in config logic.

Also, what is the parameter you give to force_rtp_proxy(...)?

Cheers,
Daniel

On 3/2/11 8:38 AM, Spinov Evgeniy wrote:
> May be I miss some important details? No suggestions?
>
> Thank you.
>
>> Hello, all.
>> Using nathelper + rtpproxy for subj. Kamailio has public and private
>> network interfaces. Asterisk is only private. RTP Proxy is working in
>> bridge mode and relaying traffic from UAC to Asterisks.
>> Everything is working fine, except one configuration. When the client is
>> behind router ( a specific one, I do not have an access there to
>> check ), and this UAC is making a call to other public extension, which
>> is behind router, then RTP Proxy is relaying traffic to the caller,
>> using another UDP port, then the packets arrive.
>> For instance:
>> UAC 1 ->  UAC 2
>> PUBLIC_IP:10>  KAMAILIO_IP:5555
>> KAMAILIO_IP:5678>  PUBLIC_IP:12
>> While for the UAC 2 it looks like:
>> PUBLIC_IP:20>  KAMAILIO_IP:6767
>> KAMAILIO_IP:4564>  PUBLIC_IP:20
>> The source and destination UDP ports are the same. As result, I can hear
>> UAC 1 and he cannot hear me.
>> In case of we have UAC 3, which is behind other router, call is working
>> fine with same configuration.
>> "It's routers fault" you can say, but in the same configuration ( I mean
>> network, not kamailio ) it worked, but when RTPProxy was not in bridge
>> mode and Kamailio and Asterisks were in public network. Reinvites are
>> not allowed in both cases.
>> The question is, why the source and destination UDP ports are different?
>> Using STUN in first case, cause without it, private IP written in
>> contacts and as result, traffic relayed from Kamailio is incorrect,
>> cause heading to private network which is unreachable.
>> Any ideas where to dig?
>
>
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-- 
Daniel-Constantin Mierla
http://www.asipto.com




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