[OpenSIPS-Users] NAT & RTPProxy

Callum Guy callum.guy at x-on.co.uk
Wed Apr 19 10:06:41 UTC 2023

Hi Gavin,

Using an RTP proxy is a good approach, you'll need to set it up in
bridge mode so that it is aware of the internal and external addresses
so that it can present the public IP to the client and private to the
application server.

You probably don't need fix_nated_sdp as rtpproxy/rtpengine will do
that for you, you'll just need to tell it which address to use which
differs for each product.

Good luck!


On Wed, 19 Apr 2023 at 06:39, Gavin Murphy via Users
<users at lists.opensips.org> wrote:
> Hello,
>     I'm trying to set up an instance of opensips to support a testing SIP phone calling into my simulated network. The client is running from a mobile phone. The connection from the client comes in from the public network, but the client sees its own IP as private ( My test network is running on virtual machines on my laptop, and is behind a NATed home router, so all of the VMs are in private IP space (192.168.x.x). It looks something like this:
> client -> mobile network (NAT) -> home router (NAT) -> opensips -> application server
> I am having trouble relaying the media from the network to the client. I have made various attempts of using the rtpproxy and the matmodule, but nothing has been successful so far. When using rtpproxy it writes the SDP going back to the client in the 183 with the internal IP. But if I just use fix_nated_sdp() the media doesn't go through the proxy server. If I try to use both (fix_nated_sdp() followed by rtpproxy_answer()), rtpproxy doesn't properly re-write the SDP (it ends up with a concatenation of the the private and the public advertised address.
> Anyone have any advice or experience with this kind of setup?
> Thanks,
> Gavin
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