On Sat, Mar 27, 2010 at 10:58 AM, Fabio Pietrosanti (naif) <lists@infosecurity.ch> wrote:
Hi all,
found our that UDP/53 port is prioritized on most mobile operators as DNS traffic.
It would be really effective to be able to use only port 53 udp for incoming RTP traffic of FS while acting as Media Relay.
I tried with: <param name="rtp-start-port" value="53"/> <param name="rtp-end-port" value="53"/>
But i got error: 2010-03-27 15:54:57.566241 [WARNING] switch_core_port_allocator.c:74 Rounding odd start port 53 to 54 2010-03-27 15:54:57.566241 [WARNING] switch_core_port_allocator.c:78 Rounding odd end port 53 to 52 2010-03-27 15:54:57.566241 [CRIT] sofia_glue.c:712 No RTP ports available! 2010-03-27 15:54:57.566241 [ERR] sofia_glue.c:1203 sofia/internal/sip:546547426@109.112.56.148:39664 I/O Error
If FS would be able to support a mode where it can receive multiple RTP streams coming from different peers on the same local port it would be very useful for mobile voip environment.
Fabio
There are many things wrong with this but let's start with the most obvious: it won't take much time for these mobile operators to distinguish your port 53 RTP traffic from real DNS traffic. Even with the same port number they look nothing alike and it would be trivial for any provider worth their salt to separate and classify the traffic accordingly. Nevermind the fact that you'd be attracting A LOT of attention for yourself. Your RTP traffic (at a rate of around 50pps) would hammer the network and potentially DoS other user's legitimate DNS traffic. Don't get greedy. P.S. - If you were interested in doing this from a research perspective I'd recommend developing your own RTP proxy (perhaps using RTPProxy or MediaProxy as a base) to accomplish your "multiplexing" goals although I think you're up for a challenge - just look at the performance implications for any IAX2 implementation and you'll see what I am talking about. -- Kristian Kielhofner http://www.astlinux.org http://blog.krisk.org http://www.star2star.com http://www.submityoursip.com http://www.voalte.com