[SR-Users] Comunication between devices RTP/SRTP and viceversa

Social Boh social at bohboh.info
Fri Jan 28 15:47:13 CET 2022


Thank you to all for the tips...

Regards

---
I'm SoCIaL, MayBe

El 27/01/2022 a las 6:39 p. m., Sergiu Pojoga escribió:
> You would achieve this in a failure route, detecting the 488|415 
> negative replies then resuming the branch with a different SDP profile.
>
> However, as others have said already, not all UAs will accept this 
> "hack". Some will consider the new branch with a CSeq NOT incrementing 
> as retransmission - and reject it with something like "482 Merged 
> Request".
>
> https://tools.ietf.org/html/rfc3261#section-8.2.2.2
>
> 8.2.2.2 Merged Requests
>
> If the request has no tag in the To header field, the UAS core MUST
> check the request against ongoing transactions. If the From tag,
> Call-ID, and CSeq exactly match those associated with an ongoing
> transaction, but the request does not match that transaction (based
> on the matching rules in Section 17.2.3), the UAS core SHOULD
> generate a 482 (Loop Detected) response and pass it to the server
> transaction.
>
> Regards,
> --Sergiu
>
> On Thu, Jan 27, 2022 at 6:26 PM Marrold <kamailio at marrold.co.uk> wrote:
>
>     Hi,
>
>     Unfortunately in my experience "Opportunistic SRTP" support is
>     broken in many UAs. There are (at least) two ways of doing it
>     covered indirectly in RFC3264
>     <https://tools.ietf.org/html/rfc3264> and the second explicitly in
>     RFC8643 <https://www.rfc-editor.org/rfc/rfc8643.html> and devices
>     seem to handle them differently. I've seen end devices that /can
>     /support SRTP choose to use standard RTP when offered the wrong
>     type of SDP body.
>
>     One thing I considered (but haven't tested so far) is using a late
>     offer to discover what format the end device expects before
>     sending an offer, but that might cause interop problems of its own.
>
>     Cheers
>
>     On Thu, Jan 27, 2022 at 10:54 PM Social Boh <social at bohboh.info>
>     wrote:
>
>         I can examine the request but how examine the answer if is a
>         Error?
>         Using a failure route?
>
>         Regards
>
>         ---
>         I'm SoCIaL, MayBe
>
>         El 27/01/2022 a las 5:39 p. m., Alex Balashov escribió:
>         > Does an examination of the SDP offer and answer respectively
>         not divine the issue?
>         >
>         >> On Jan 27, 2022, at 5:35 PM, Social Boh
>         <social at bohboh.info> wrote:
>         >>
>         >> I'm trying to configure Kamailio to permit communication
>         between devices:
>         >>
>         >> some use TLS and SRTP
>         >>
>         >> some UDP and RTP
>         >>
>         >> with RTPEngine in the middle.
>         >>
>         >> A priori I don't know if the device support SRTP or RTP so
>         in the routing I have to detect on the fly how to act. The
>         problem is this:
>         >>
>         >> Call from RTP to SRTP device: 488 Not Acceptable here
>         >>
>         >> Call from SRTP to RTP device: 415 Unsupported Media Type
>         >>
>         >> Any hint?
>         >>
>         >> Thank you
>         >>
>         >>   Regards
>         >>
>         >> --
>         >> ---
>         >> I'm SoCIaL, MayBe
>         >>
>         >>
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