[OpenSIPS-Users] b2b top-hiding and SDP origin line

[Ovidiu Sas]

What's the point of hiding the o= line?
The c= line will still reveal the connection IP for RTP.

If you want true topology hiding, then use two servers and chain them:
 - opensips with rtpproxy;
 - opensips as a b2bua with "top hidding".

On the rtpproxy server you will be able to mask everything on the SDP
side (see the 'o' flag for rtpproxy commands).


Regards,
Ovidiu Sas

On Tue, Feb 8, 2011 at 2:40 PM, Jeff Pyle <jpyle at fidelityvoice.com> wrote:
> Hello,
> Since the top-hiding scenario doesn't touch the SDP, it seems some
> extracurricular textops may be required to fully hide the topology of the
> network.  I've been trying various subst_body() functions on my b2b Opensips
> instance, each failing in a new and wonderful way.
>
> route[b2b_request] {
>         if (search("Content-Type: application/sdp")) {
>                 xlog("L_INFO", "Attempting to rewrite origin line in
> b2b_request\n");
>                 subst_body('/^o=.*/o=request 12345 67890 IN IP4 8.4.6.2/');
>         }
> }
> route[b2b_reply] {
>         if (search("Content-Type: application/sdp")) {
>                 xlog("L_INFO", "Attempting to rewrite origin line in
> b2b_reply\n");
>                 subst_body('/^o=.*/o=reply 12345 67890 IN IP4 8.4.6.2/');
>         }
> }
> local_route {
>         if (search("Content-Type: application/sdp")) {
>                 xlog("L_INFO", "Attempting to rewrite origin line in
> local_route\n");
>                 subst_body('/^o=.*/o=local 12345 67890 IN IP4 8.4.6.2/');
>         }
> }
>
> With the above config, the initial INVITE b2b'd through
> with b2b_init_request("top hiding") does have it's origin line operated
> upon.  After that, I see two xlogs hit from within b2b_reply on the 183 and
> 200 coming back through, but the subst_body commands have no effect.
> No, I'm not really going to rewrite my origin lines to a static value like
> this; this is just for testing.  And the test is not going well.
> How does one affect the origin line in a b2b environment for true topology
> hiding?  Or, is that the key, that it must be done outside of a b2b
> environment?
>
> - Jeff
>
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