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

Örn Arnarson orn at arnarson.net
Thu Oct 15 11:55:56 CEST 2009


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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