[SR-Users] Rtpengine - no RTP packets going out

[Richard Fuchs]

On 01/04/2019 09.14, Istvan Mogyorosi wrote:
> Dear all,
>
> This is my first post after reading a lot in this mailing-list.
> I'm trying to use Kamailio 5.1 with the dispatcher module and 
> rtpengine acting as SIP + RTP proxy.
> I have 6 asterisk servers in a private subnet that should talk with 
> the peer via a single IP like this:
>
> Asterisk 1..n|---> | GW.PRIVATE.IP -o- GW.PUBLIC.IP |----> PEER.SIP.TRUNK
>
> I'm on Centos 7, with firewalld configured, iptables module is loaded 
> and the rule is well defined.
> Packet forwarding is also enabled.
>
> Chain rtpengine (1 references)
> target     prot opt source               destination
> RTPENGINE  udp  --  anywhere             anywhere RTPENGINE id:40
>
> My call flow seems to be fine, Kamailio/rtpengine private IP is the 
> outboundproxy parameter of Asterisk instances.
>
> My problem is that RTP packets are not present on the public 
> interface, the rtpengine final log showing
> the 2 sessions, but I'm not sure this is what I want or simply the 
> firewall does not let it out ?
> (To be more precise PEER.SIP.TRUNK is the trunk for SIP traffic, I 
> have multiple IP addresses
> for media to connect to, reinvites are allowed)
>
> Closing call due to timeout
> Final packet stats:
> --- Tag 'as6d12caea', created 1:00 ago for branch '', in dialogue with 
> 'as541b1e61'
> ------ Media #1 (audio over RTP/AVP) using unknown codec
> --------- Port  GW.PRIVATE.IP:10000 <> 192.168.30.13:11152, SSRC 0, 0 
> p, 0 b, 0 e, 60 ts
> --------- Port  GW.PRIVATE.IP:10001 <>   192.168.30.13:11153 (RTCP), 
> SSRC 0, 0 p, 0 b, 0 e, 60 ts
>
> --- Tag 'as541b1e61', created 1:00 ago for branch '', in dialogue with 
> 'as6d12caea'
> ------ Media #1 (audio over RTP/AVP) using unknown codec
> --------- Port     GW.PUBLIC.IP:10000 <> PEER.SIP.TRUNK:28216, SSRC 0, 
> 0 p, 0 b, 0 e, 60 ts
> --------- Port     GW.PUBLIC.IP:10001 <> PEER.SIP.TRUNK:28217 (RTCP), 
> SSRC 0, 0 p, 0 b, 0 e, 60 ts
>
These are all reception counters, so this is a problem of packets not 
being received. Having the iptables RTPENGINE rule installed does not 
automatically allow the packets to pass through your firewall. You have 
to do that separately.

Cheers