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

Marrold kamailio at marrold.co.uk
Fri Jan 28 00:24:26 CET 2022


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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