Subject: [MMUSIC] I-D ACTION:draft-ietf-mmusic-sdp-comedia-05.txt

From: [email-masked]
Date: Fri, 07 Mar 2003 15:35:51 -0500

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Multiparty Multimedia Session Control Working Group of the IETF.

	Title		: Connection-Oriented Media Transport in SDP
	Author(s)	: D. Yon
	Filename	: draft-ietf-mmusic-sdp-comedia-05.txt
	Pages		: 14
	Date		: 2003-3-7
	
This document describes how to express media transport over 
connection-oriented protocols using the Session Description Protocol 
(SDP).  It defines two new protocol identifiers: TCP and TLS.  It 
also defines the syntax and semantics for an SDP 'direction' 
attribute that describes the connection setup procedure.

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From: Magnus Westerlund <[email-masked]>
Date: Tue, 11 Mar 2003 18:12:02 +0100

Hi,

I have some comments on the COMEDIA draft. I still reading up on this so you will not get one of these 20+ comment letters that some other drafts has got. 

1. The draft seems very directed at SIP usage only. It does not really describe how to handle comedia in the context of SAP or for that matter RTSP. In SAP or other uni-directional use cases it will be required that the SDP describes a passive side as the server can never connect as it does not know of the client. In regards to RTSP the port number MUST not be 0 comes into conflict. It seems relevant that a RTSP controlled server actually offers a media block which uses reliable connection oriented transport. SO this needs to be addressed I think. 

2. The security consideration chapter seems to be missing the important hijacking warning. If I don't misunderstand section 4.6 a passive side actually starts sending to the address of the first received packet. This is very unsecure and easy to hijack. Should definitely be addressed in the  security consideration.

3. IANA Considerations. This chapter needs to better clarify what exactly is registered in what registries. I also think that the definitions of the new attributes should be done better using ABNF of RFC 2234 and draft-ietf-mmusic-sdp-new. 

Regards 

Magnus Westerlund 

Multimedia Technologies, Ericsson Research ERA/TVA/A
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From: David Yon <[email-masked]>
Date: Fri, 14 Mar 2003 22:34:05 -0500

Is this really a problem for SAP?  Presumably the server would be publicly 
routable and therefore it would make sense to advertise passive.

Do you have any suggestions re: the RTSP port-zero conflict?

Security considerations will come back in comedia-06.  See my other 
posting, and this will be discussed at the meeting.

If someone wants to give me more guidance on the IANA and ABNF (starting 
with some group consensus that this is really an issue to be address), I'm 
all ears.

At 12:12 PM 3/11/2003, Magnus Westerlund wrote:
>Hi,
>
>I have some comments on the COMEDIA draft. I still reading up on this so 
>you will not get one of these 20+ comment letters that some other drafts 
>has got.
>1. The draft seems very directed at SIP usage only. It does not really 
>describe how to handle comedia in the context of SAP or for that matter 
>RTSP. In SAP or other uni-directional use cases it will be required that 
>the SDP describes a passive side as the server can never connect as it 
>does not know of the client. In regards to RTSP the port number MUST not 
>be 0 comes into conflict. It seems relevant that a RTSP controlled server 
>actually offers a media block which uses reliable connection oriented 
>transport. SO this needs to be addressed I think.
>2. The security consideration chapter seems to be missing the important 
>hijacking warning. If I don't misunderstand section 4.6 a passive side 
>actually starts sending to the address of the first received packet. This 
>is very unsecure and easy to hijack. Should definitely be addressed in 
>the  security consideration.
>
>3. IANA Considerations. This chapter needs to better clarify what exactly 
>is registered in what registries. I also think that the definitions of the 
>new attributes should be done better using ABNF of RFC 2234 and 
>draft-ietf-mmusic-sdp-new.
>Regards
>
>Magnus Westerlund