[SR-Users] RTPEngine Intermittent One Way Audio Issue SRTP => RTP

[Richard Fuchs]

On 07/02/15 03:09 AM, Tim Chubb wrote:
> Hi,
> 
>  
> 
> I am currently experiencing an intermittent one way audio issue, when
> using RTPEngine and proxying between srtp  and rtp.  There is no
> apparent pattern, I have managed to repeat the  on the 7^th , 23^rd ,
> and 63^rd calls to a test number, where upon connection only audio in
> the RTP => SRTP direction was working.  All other test calls worked as
> normal.  Digging through the RTPEngine log file the only abnormalities I
> can see are: Discarded invalid SRTP packet: authentication failed
> entries on the calls that had the one way audio issue. 

Your caller side uses an SRTP authentication tag and apparently
sometimes fails to calculate it correctly (or rtpengine does). You'd
have to a packet capture of the RTP traffic to see what exactly is going
on. Using the crypto tags found in the SDP, it's possible to verify the
authentication tags (I believe Wireshark does that automatically in some
cases).

cheers