Subject: [AVT] Any thoughts on documenting RTP/RTCP port usage?

From: "Jean-Francois Mule" <[email-masked]>
Date: Fri, 17 Oct 2003 10:48:16 -0600

I'm curious to know whether there has been some discussion on documenting the RTP/RTCP port use in the real world today. Many applications use RTP&RTCP and random UDP ports outside the IANA registry. Some RTP entries exist in the IANA registry today (see below), but most commonly used RTP applications don't have an entry.

Some operators may want to be able to establish strict firewall rules on UDP traffic. This is where some kind of registry for RTP traffic could help, especially since there are some streaming applications that consistently use the same not-that-well-known ports.

Any thoughts on this? Has an RTP port registry been considered? Is this a bad idea?
Thanks in advance,
Jean-François 
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paging-port     3771/tdp   RTP Paging Port
paging-port     3771/udp   RTP Paging Port
#                          Patrick Ferriter <[email-masked]> June 2003

espeech-rtp     8417/tcp    eSpeech RTP Protocol
espeech-rtp     8417/udp    eSpeech RTP Protocol
#                           Scott Tarone <[email-masked]> April 2003

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

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From: Magnus Westerlund <[email-masked]>
Date: Mon, 20 Oct 2003 09:48:52 +0200

Hi Jean-Francois,

I can't recall any such debate during the almost 4 years that I have 
been active in the AVT. However I do understand the reason for not 
having that debate. As RTP is currently used in SIP and RTSP, MBONE, 
i.e. per session dynamic assignment of ports, there has been little 
reason. Thus any RTP application usually needs at least a range to be used.

I know that certain ranges declared for example in the Real Networks 
player has become almost defacto standard within the streaming 
community. However this is for one certain application. I don't know if 
the SIP clients out there uses any special range.

I think that the definition of port ranges will only restrict the 
applications and does not provide any real security. For example by 
defining a port range for a certain application it will force any new 
application into the same ranges, otherwise there will be FW traversal 
problems. From a security stand point the FW can't accept any IP/UDP/RTP 
traffic simply because it is within the range, it will need to check 
this against the application level requests for traffic. If the FW 
anyway are doing the checking or clients are using a MIDCOM protocol the 
FW can open any ports and there are no need for ranges.

Due to the above reasons I think it is a bad idea. I guess that others 
have their own view on this.

Cheers

Magnus

-- 

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
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