[OpenSIPS-Users] fix_nated_sdp and rtpproxy

Bogdan-Andrei Iancu bogdan at opensips.org
Thu Nov 16 11:26:47 EST 2017


Using the "i" and "e" flags to control the RTP interfaces does not 
affect the "learning" mode. You should you "r" flag only if the received 
IP in SDP is public. Otherwise do not use it.

Regards,

Bogdan-Andrei Iancu
   OpenSIPS Founder and Developer
   http://www.opensips-solutions.com

On 11/16/2017 03:07 PM, Yury Kirsanov wrote:
> Hi Bogdan,
> Thanks for clarification, I didn't know that RTP Proxy learns from 
> source packets, it's quite hard to find documentation on it. The 
> problem here is that I'm using RTP Proxy in bridge mode, connecting 
> public interface with internal LAN and my upstream providers are using 
> sets of their own proxies too, besides customers connecting to this 
> OpenSIPS server. So I have to use flag "r" (and, of course, flags of 
> direction - "i" and "e") or else there would be no audio on calls when 
> SDP in provider's answer is different from SIP packet source IP. Of 
> course, I can analyze where the initial INVITE packet is coming from 
> and enable different options but that would be more complex rather 
> than just have SDP modified before passing it to RTP Proxy.
> Regards,
> Yury.
>
> 2017-11-17 0:01 GMT+11:00 Bogdan-Andrei Iancu <bogdan at opensips.org 
> <mailto:bogdan at opensips.org>>:
>
>     Hi Yury,
>
>     RTPproxy learns not only from SDP, but based on the incoming RTP
>     traffic. Your Client will send RTP to RTPproxy (as the Client will
>     receive back a valid IP in the SDP) and RTPproxy will see where
>     the RTP traffic comes from and starts sending back RTP to that
>     IP:port.
>
>     Just be sure you do not use the "a" and "r" flags when calling
>     rtpproxy engage.
>
>     Regards,
>
>     Bogdan-Andrei Iancu
>        OpenSIPS Founder and Developer
>        http://www.opensips-solutions.com <http://www.opensips-solutions.com>
>
>     On 11/16/2017 02:48 PM, Yury Kirsanov wrote:
>>     Hi Bogdan,
>>     Thanks for your answer and support! But the issue is that there
>>     is a private IP address in SDP coming from the client so if I
>>     just pass it via RTP proxy - it would learn that incorrect IP and
>>     would try to forward packets to it causing one-way audio. That's
>>     why I first wanted to overstamp that incorrect IP with received
>>     IP and then pass it to the RTP Proxy. Hope this makes my idea clear.
>>
>>     Regards,
>>     Yury.
>>
>>     2017-11-16 23:32 GMT+11:00 Bogdan-Andrei Iancu
>>     <bogdan at opensips.org <mailto:bogdan at opensips.org>>:
>>
>>         Hi Yury,
>>
>>         Why do you need to update the incoming SDP before engaging
>>         RTPproxy ? Just pass to it whatever you get into SDP (even if
>>         private) and let rtpproxy to "learn" the correct IP:port of
>>         the media end points based on the incoming traffic.
>>
>>         Regards,
>>
>>         Bogdan-Andrei Iancu
>>            OpenSIPS Founder and Developer
>>            http://www.opensips-solutions.com
>>         <http://www.opensips-solutions.com>
>>
>>         On 11/14/2017 04:05 AM, Yury Kirsanov wrote:
>>>         Hi,
>>>         I have a problem with remote client who can't properly
>>>         configure NAT and is sending private IP in all SDP and SIP
>>>         packets. I've resolved issues with registration but can't
>>>         resolve the issue with SDP. My topology is as following:
>>>
>>>         <Client> ----- <NAT router> ------- <RTP Proxy> ----------
>>>         <OpenSIPS> -------- <NAT> ----------- <PBX>
>>>
>>>         So, I need to simultaneously engage RTP Proxy to bridge
>>>         external Internet and our local LAN and need to rewrite SDP
>>>         body of original Client's packet with received IP address.
>>>         If I'm doing fix_nated_sdp and then rtpproxy_offer - I'm
>>>         getting doubled IPs in SDP message, like this:
>>>
>>>         100.11.100.200192.168.20.200
>>>
>>>
>>>         Is there any way to update SDP of client's packet and then
>>>         command RTP Proxy to use updated IP? Thanks!
>>>
>>>
>>>
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>>
>>
>
>

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