[OpenSIPS-Users] Filtering out RFC6263 traffic on Mediaproxy

[Bogdan-Andrei Iancu]

Hi Andreas,

Your thinking seams to be flawless - I would also think that dropping 
the packages at iptable level or media relay level is the best think to do.

One question (when reading the RFC): when they say "Empty (0-Byte) 
Transport Packet" this mean an UDP package of 0 len or an UDP package 
that has RTP with 0 payload ??

Regards,
Bogdan

On 11/25/2011 06:35 PM, Andreas Sikkema wrote:
> Guys,
>
> I'm currently routing some calls from one VoIP platform to another
> OpenSIPS based platform using two ISDN to SIP gateways that are
> connected back to back. This setup is quite recource heavy, expensive
> and has a limited capacity. So I'm thinking of connecting both
> platforms using a (well protected) SIP interconnection. That part is
> easy, we've done that before.
>
> The problem is in the RTP some phones, connected to the old platform,
> are sending out. Every 30 seconds or so they send out 0 length RTP
> messages that some SIP UAs really don't like. Some hardware will
> hangup a call when it receives 0 length UDP frames in an RTP stream,
> others will stop handling the incoming RTP traffic allthogether
> resulting in one way audio. The 0 length UDP messages appear to
> conform to RFC6263 (http://tools.ietf.org/html/rfc6263) which is
> really new...
>
> I've tried talking to the manufacturer of the phones, talked to the
> supplier of the VoIP platform, talked to everyone and their neighbour
> and all say it's not their problem. I've identified two places where
> *I* can solve it.
>
> - In our core routers
> - At every mediaproxy machine
>
> The first option is sub-optimal, I don't want all our routers having a
> drop-this-packet "firewall" line for various reasons. The second
> option I've started to like more and more. There's two ways to resolve
> this:
> - I just make sure I add an iptables call somewhere in the startup script, or
> - I/We add an RFC6263 configuration option to Mediaproxy that does
> more or less the same
>
> The iptables call would drop all 0 length UDP messages sent to the
> mediaproxy ports.
>
> Am I wrong in my thinking?
>


-- 
Bogdan-Andrei Iancu
OpenSIPS Founder and Developer
OpenSIPS solutions and "know-how"