[Kamailio-Users] Having problems using RTPProxy to bridge internal/external networks

[Alex Balashov]

We attempted that formula as well.  The problem is that rtpproxy won't 
actually forward the packets to the other interface when started in what 
is supposed to be bridging mode, i.e.

   rtpproxy -F -s udp:xxx.xxx.xxx.xxx:5060 -l outside.ip/inside.ip

I enabled /proc/sys/net/ipv4/ip_forward but it did not help.

Daniel-Constantin Mierla wrote:

> Hello,
> 
> I have several rtp bridging deployments, I started from alg.cfg
> 
> http://openser.svn.sourceforge.net/viewvc/openser/trunk/modules/nathelper/examples/alg.cfg?revision=2&view=markup 
> 
> 
> Cheers,
> Daniel
> 
> 
> On 15.10.2009 17:06 Uhr, Örn Arnarson wrote:
>> Hi Klaus,
>>
>> Yes, I have learned that both are not to be used. However, I am unable
>> to get the SDP to change with the force_rtp_proxy call. Can you see
>> anything wrong with the way I am calling it? The call is clearly in
>> effect, as it does change the media addresses, just not to what I need
>> them to be. Even if I do specify them explicitly in the call.
>>
>> Best regards,
>> Örn
>>
>> 2009/10/15 Klaus Darilion <klaus.mailinglists at pernau.at>:
>>  
>>> never call both functions. That will not work (you see the result)
>>>
>>> when using the correct parameters (flags), force_rtpproxy() should be 
>>> able
>>> to fix the SDP correctly
>>>
>>> regards
>>> klaus
>>>
>>> Örn Arnarson wrote:
>>>    
>>>> Hi Klaus,
>>>>
>>>> I've gathered as much; I'm able to bridge between the interfaces, but
>>>> if I do that, I can't rewrite the SDP properly. I can only rewrite the
>>>> SDP by using fix_nated_sdp. If I use fix_nated_sdp and the rtpproxy
>>>> functions to bridge the call, the SDP gets messed up.
>>>> E.g. I rewrite the media address with fix_nated_sdp from the public
>>>> IP, 157.157.x.x to 10.252.1.8, but if I then call the force_rtp_proxy
>>>> function, it just appends the public IP address directly behind the
>>>> 10.252.1.8 IP address, so the SDP media address is now
>>>> 10.252.1.8157.157.x.x.
>>>>
>>>> Any ideas?
>>>>
>>>> Regards,
>>>> Örn
>>>>
>>>> On Thu, Oct 15, 2009 at 12:30 AM, Klaus Darilion
>>>> <klaus.mailinglists at pernau.at> wrote:
>>>>      
>>>>> I think it is not about offer/answer, but you have to call rtpproxy*
>>>>> functions with  the proper parameter to activate bridging inside
>>>>> rtpproxy.
>>>>>
>>>>> E.g. there is an (I guess rather old) example for ipv4 to ipv6 
>>>>> bridging,
>>>>> but
>>>>> from the logic it should be similar to v4:v6 bridging:
>>>>>
>>>>> http://openser.svn.sourceforge.net/viewvc/openser/trunk/modules/nathelper/examples/4to6.cfg?revision=2&view=markup 
>>>>>
>>>>>
>>>>> Take a look at the i and e flag:
>>>>> http://kamailio.org/docs/modules/1.5.x/nathelper#id2468157
>>>>>
>>>>> regards
>>>>> klaus
>>>>>
>>>>> Joe Hart wrote:
>>>>>        
>>>>>> Hi all,
>>>>>>
>>>>>> For a project on which I'm currently working, I am having some 
>>>>>> problems
>>>>>> figuring out how to correctly configure Kamailio to communicate 
>>>>>> with RTP
>>>>>> Proxy in order to send media into and out of a network with 
>>>>>> private IP
>>>>>> address ranges.
>>>>>>
>>>>>> I have a proxy set up to send the SIP traffic, and all of this is
>>>>>> working
>>>>>> fine.  However, I'm having some trouble getting the RTP Proxy set up.
>>>>>>  Currently, when the call is connected, the offer/answer is made 
>>>>>> and RTP
>>>>>> Proxy seems to be taking over, but I'm having trouble getting my 
>>>>>> audio
>>>>>> to
>>>>>> flow in both directions.
>>>>>>
>>>>>> Examination of the traffic coming into and out of this machine 
>>>>>> seems to
>>>>>> indicate that the IP addresses aren't being mangled correctly.
>>>>>> Specifically,
>>>>>> it appears the internal IP address isn't being changed to reflect 
>>>>>> the IP
>>>>>> address of the machine on which RTP Proxy is running, so that when 
>>>>>> the
>>>>>> caller tries to send audio back, the IP it's given to reply to is
>>>>>> 10.10.x.x,
>>>>>> which obviously won't work.
>>>>>>
>>>>>> I have tried experimenting with specifically setting IP addresses 
>>>>>> in the
>>>>>> rtpproxy_offer() and _answer() methods to no avail, as well as 
>>>>>> setting
>>>>>> various flags in those methods.  However, I must admit that I'm not
>>>>>> entirely
>>>>>> sure what's happening under the hood with these methods, or what
>>>>>> rtpproxy is
>>>>>> doing with that information when it gets it.  Rather than continue to
>>>>>> hack
>>>>>> at this by trial and error, I'm hoping someone here can point me 
>>>>>> in the
>>>>>> right direction.
>>>>>>
>>>>>> Any advice, example code or pep talks would be greatly appreciated.
>>>>>>
>>>>>> Thanks in advance,
>>>>>>
>>>>>>           
>>>>> _______________________________________________
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>>>>>
>>>>>         
>>
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> 


-- 
Alex Balashov - Principal
Evariste Systems
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