Re: SRTP encrypted calls error
Guillaume BERAUDO <guillaume.beraudo <at> belledonne-communications.com>
2012-01-03 10:02:42 GMT
Linphone invites the remote part with SRTP information:
m=audio 7078 RTP/SAVP 110 111 112 3 8 0 101
a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
a=crypto:2 AES_CM_128_HMAC_SHA1_32 inline:YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY
But the answer sent by the iptel Sip Express Media Server doesn't contain
m=audio 10576 RTP/AVP 110 3 8 0 101
That is why the call fails.
The behaviour expected by Linphone is that the remote part refuse call if it
cannot handle SRTP. Then Linphone would try a non encrypted invite.
Right now, your only solution is to disable SRTP.
On the Linphone side, I will update the "no codec intersection" UI error message
to a more general one.
RFC 4568 - 5.1.2:
When the answerer receives the initial offer with one or more crypto
attributes for a given unicast media stream, the answerer MUST either
accept exactly one of the offered crypto attributes, or the offered
stream MUST be rejected.
> >> Dear all
> >> Is it normal that when I'm selecting 'SRTP' encryption and making a
> >> call to, say, <sip:echo <at> iptel.org>, I get the following error:
> >> "No codec intersection"
> >> I find the following message in teh log:
> >> "error: Incompatible SDP offer received in 200Ok, need to abort the
> >> call".
> >> Using Linphone 3.5.0 on Ubuntu Lucid, compiled against
> >> 'srtp-1.4.4'.