Hi Carlos.

That is what I'm looking for and now trying to understand if it is sufficient 
for may case.

With this function I will be able to fix IP. But I still have to fix Ports.


If there are NATs, so I suppose there is some kind of Ports mapping that has to 
be taken into account when solving the NAT traversal.  I and a coworker are 
investigating how to solve the port mapping. Maybe the solution will demand ICE 
and STUN. We can't use media proxy module, because our hardware will not be 
able to do media relay. So, We can have a media relay in the same place as 
OpenSIPs.



Thanks a lot.


RODRIGO PIMENTA CARVALHO
Inatel Competence Center
Software
Ph: +55 35 3471 9200 RAMAL 979


________________________________
De: users-boun...@lists.opensips.org <users-boun...@lists.opensips.org> em nome 
de Carlos Eduardo <kad...@gmail.com>
Enviado: quinta-feira, 31 de março de 2016 11:43
Para: OpenSIPS users mailling list
Assunto: Re: [OpenSIPS-Users] What is the module to fix SDP ?

Hello Rodrigo,

Maybe the function fix_nated_sdp, from nathelper module, would help.

1.5.2.  fix_nated_sdp(flags [, ip_address])

Alters the SDP information in orer to facilitate NAT traversal. What changes to 
be performed may be controled via the "flags" paramter.

Meaning of the parameters is as follows:

flags - the value may be a bitwise OR of the following flags:
0x01 - adds "a=direction:active" SDP line;
0x02 - rewrite media IP address (c=) with source address of the message or the 
provided IP address (the provide IP address take precedence over the source 
address).
0x04 - adds "a=nortpproxy:yes" SDP line;
0x08 - rewrite IP from origin description (o=) with source address of the 
message or the provided IP address (the provide IP address take precedence over 
the source address).

ip_address - IP to be used for rewriting SDP. If not specified, the received 
signalling IP will be used. The parameter allows pseudo-variables usage. NOTE: 
For the IP to be used, you need to use 0x02 or 0x08 flags, otherwise it will 
have no effect.

This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE, FAILURE_ROUTE, 
BRANCH_ROUTE.

Example:
if (search("User-Agent: Cisco ATA.*") {fix_nated_sdp("3");};


2016-03-30 14:57 GMT-03:00 Rodrigo Pimenta Carvalho 
<pime...@inatel.br<mailto:pime...@inatel.br>>:

Hi.


I have a case when a peer answering a call (INVITE) is behind a NAT.

So, in its SIP OK message I would like to see the SDP containing a valid IP and 
media Port valid to receive audio from the caller. That is, the caller need to 
know a valid IP and Port where he/she can send his/her audio packets.


1 - Is it possible to "fix" SDP content for such objective?

2 - Can OpenSIPS do something for this idea works or must I to use something 
more like a stun server?

3 - What is the OpenSIPS module that can help me with this task?


I guess I will have to fix 2 fiels in SDP:

    Media Description, name and address (m): audio 55142 RTP/AVP 8 101  ( to 
fix the port)
    Connection Information (c): IN IP4 192.168.100.156                          
        ( to fix the IP)


P.S.: I have already a solution (opensips.cfg) that let SIP messages cross NATs 
without problems. Only SDP has to be fixed.


Any hint will be very helpful!

Best regards.



RODRIGO PIMENTA CARVALHO
Inatel Competence Center
Software
Ph: +55 35 3471 9200<tel:%2B55%2035%203471%209200> RAMAL 979

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--
Carlos E. Wagner
Tecnólogo em Telecomunicações, OCP, dCAA

Gnotel Tecnologia
E-mail: kad...@gmail.com<mailto:kad...@gmail.com>
Fone: +55 48 9981-0894
Skype: carlos.e.wagner
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