[SR-Users] RTPENGINE question

[Richard Fuchs]

On 11/09/2020 15.29, Andrew Chen wrote:
> Thanks Alex.
>
> So it turns out my rtpengine stopped working after our latest kernel 
> upgrade to:
>
> Linux sjomainrtpe30 5.3.0-1035-aws #37-Ubuntu SMP Sun Sep 6 01:17:09 
> UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
>
> at the time, I was running an older version 8.0.x so I recompiled all 
> the ngcp packages under this kernel and completed the installation 
> without issues.
>
> As soon as we started making test calls, I received 0 audio from those 
> test endpoints.  Looking at the rtpengine logs, I see several messages 
> that's quite concerning:
>
> Sep 11 18:43:41 sjomainrtpe30 kernel: [  13.434623] xt_RTPENGINE: 
> loading out-of-tree module taints kernel.
> Sep 11 18:43:41 sjomainrtpe30 kernel: [  13.434670] xt_RTPENGINE: 
> module verification failed: signature and/or required key missing - 
> tainting kernel
> Sep 11 18:43:41 sjomainrtpe30 kernel: [  13.434938] Registering 
> xt_RTPENGINE module - version 9.0.1.0+0~mr9.0.1.0
>
> and
>
> Sep 11 18:49:50 sjomainrtpe30 rtpengine[1030]: WARNING: 
> [2-7859 at 2600:1f1c:4ff:3e01:f64d:2f67:c0fa:c931 port 50000]: No support 
> for kernel packet forwarding available (decryption cipher or HMAC not 
> supported by kernel module)

We don't actually have any crypto suites in the code which aren't also 
supported by the kernel module, so there's something else going on. Even 
with this error popping, forwarding should fall back to userspace mode 
and you should have audio. There's probably some other messages in the 
log which point to the real underlying cause, possibly some SRTP-related 
negotiation issues (DTLS?)

Cheers