[OpenSIPS-Users] rtpproxy sends rtp from caller to callee before 200OK

Răzvan Crainea razvan at opensips.org
Thu Jan 22 14:12:14 CET 2015


Hi Marco!

As Patrick suggested, adding the a:sendonly line in RTP should instruct 
the caller not to send any RTP. However, if I remember correctly, I've 
seen legitimate clients that still send RTP.
On a different note, they are sending RTP to a media gateway, right? And 
most likely the B part will ignore all the RTP.

Best regards,

Răzvan Crainea
OpenSIPS Solutions
www.opensips-solutions.com

On 01/22/2015 02:50 PM, Patrick Wakano wrote:
> Ok Marco,
> Your concern is with hackers and not misuse! Really valid nowadays!
>
> Patrick
>
> On Thu, Jan 22, 2015 at 8:32 AM, Marco Hierl 
> <marco.hierl at mrnetgroup.com <mailto:marco.hierl at mrnetgroup.com>> wrote:
>
>     Hi Patrik,
>
>     thanks for this idea!
>
>     I did not say clear enough: I’m afraid that anybody can cheat us.
>     My intention is to assure that our interconnection partners (or
>     their customers) do not have the possibility to make a
>     conversation without being charged.
>
>     Sending the indication “a:sendonly” only means, that the client is
>     told not to send RTP, but IF it send RTP anyway then the RTPproxy
>     leads in on to the callee. So, it is not in my hands then!
>
>     Best regards from Hamburg
>
>       Marco
>
>     *Von:*users-bounces at lists.opensips.org
>     <mailto:users-bounces at lists.opensips.org>
>     [mailto:users-bounces at lists.opensips.org
>     <mailto:users-bounces at lists.opensips.org>] *Im Auftrag von
>     *Patrick Wakano
>     *Gesendet:* Donnerstag, 22. Januar 2015 11:16
>     *An:* OpenSIPS users mailling list
>
>     *Betreff:* Re: [OpenSIPS-Users] rtpproxy sends rtp from caller to
>     callee before 200OK
>
>     Have you tried to insert a "a:sendonly" line in your SDP body when
>     sending it to the caller?
>     If the client receives such line it should not send media...
>
>     Then in the 200Ok you can put an "a:sendrecv" line to establish
>     full media path!
>
>     It's just an idea, I'm not sure if it will really work...
>
>     Patrick
>
>     On Thu, Jan 22, 2015 at 6:51 AM, Marco Hierl
>     <marco.hierl at mrnetgroup.com <mailto:marco.hierl at mrnetgroup.com>>
>     wrote:
>
>     Hi Răzvan,
>
>     Ok, thanks for your answer!
>
>     Unfortunately we are offering „early media“ to our customers (call
>     center, radio station, and other companies) and lots of them like
>     to play a free-of-charge announcement in the beginning. But if we
>     started to get cheated, maybe we need to go for this workaround.
>
>     But apart from that: Mostly the SDP is NOT repeated in the 200OK.
>     Can I call rtpproxy_answer() when receiving the 200OK anyway?
>
>     Thanks and best regards
>
>       Marco
>
>     *Von:*users-bounces at lists.opensips.org
>     <mailto:users-bounces at lists.opensips.org>
>     [mailto:users-bounces at lists.opensips.org
>     <mailto:users-bounces at lists.opensips.org>] *Im Auftrag von *Razvan
>     Crainea
>     *Gesendet:* Donnerstag, 22. Januar 2015 09:36
>     *An:* users at lists.opensips.org <mailto:users at lists.opensips.org>
>     *Betreff:* Re: [OpenSIPS-Users] rtpproxy sends rtp from caller to
>     callee before 200OK
>
>     Hi, Marco!
>
>     From RTPProxy point of view, you can't differentiate between SIP
>     replies, because for all of them you call the same function -
>     rtpproxy_answer().
>     Now, if the client decides to send RTP for 183 (and indeed, I've
>     seen this several times), there's not that much that you can do.
>     Although it's kind of a hack, all I can think of is to not call
>     rtpproxy_answer() for 180/183 and strip the body to prevent the
>     client from sending RTP directly to the callee.
>     I hope this works for you.
>
>     Best regards,
>
>     Răzvan Crainea
>
>     OpenSIPS Solutions
>
>     www.opensips-solutions.com  <http://www.opensips-solutions.com>
>
>     On 01/21/2015 04:07 PM, Marco Hierl wrote:
>
>         Dear all,
>
>         first of all I need to apologize that I was not able to find
>         information about this issue although I’m sure that I’m not
>         the first one complaining!
>
>         The caller is sending an INVITE via OpenSIPS and
>         rtpproxy_offer() is executed, callee answers with REPLY 180 or
>         REPLY 183 (with SDP) and rtpproxy_answer() is made. In this
>         status it should be ok that the rtp stream from callee to
>         caller is transferred via the rtpproxy (e.g. for
>         announcements), but I can see that rtp stream from caller to
>         callee is transferred too!!! This means that there can be a
>         conversation without receiving the 200OK and what is the real
>         problem: that means (at least for me) they can talk to each
>         other without any charging !! A timer will stop the conversion
>         after the a while, but this can take time.
>
>         How can I overcome this problem? How can prevent RTP to be
>         send to the callee before REPLY 200 is received?
>
>         I can’t find any help in the RTPproxy protocol
>         http://www.b2bua.org/wiki/RTPproxy/Protocol, nor in the
>         rtpproxy module description in OpenSIPS.
>
>         Thanks for your ideas, and best regards
>
>           Marco
>
>
>
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