[Freeswitch-users] Accepting an "optional" SRTP offer (crypto in RTP/AVP) and establishing SRTP

[William Simon]

Can anyone offer insight into this matter?

Endpoint offers RTP/AVP with crypto. We want Freeswitch to respond to the RTP/AVP and agree to the crypto and do SRTP.


> On Oct 5, 2018, at 10:27 AM, William Simon <wsimon at stratusvideo.com> wrote:
>
> We are working with an endpoint that offers optional SRTP in the non-RFC-compliant way of an a=crypto attribute within RTP/AVP.
>
> I have told FreeSWITCH to allow this with rtp_allow_crypto_in_avp=true at the right place in the dialplan.
>
> Immediately after that in the dialplan I have to reject SRTP by using rtp_secure_media=forbidden, otherwise the call setup still fails. By setting the value to forbidden, the call does proceed unencrypted.
>
> We want FreeSWITCH to proceed with media encryption. Setting rtp_secure_media to any other value results in FreeSWITCH rejecting the offer like this:
>
> v=0
> o=FreeSWITCH 1538660754 1538660755 IN IP4 192.168.100.104
> s=FreeSWITCH
> c=IN IP4 192.168.100.104
> t=0 0
> m=audio 0 RTP/AVP 19
> m=video 0 RTP/AVP 19
>
> Is there anything else I can do to force SRTP in the answer?
>



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