Subject: [MMUSIC] I-D Action:draft-ietf-mmusic-rtsp-nat-evaluation-01.txt

From: [email-masked]
Date: Fri, 11 Jul 2008 05:00:02 -0700 (PDT)

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           : The evaluation of different NAT traversal Techniques for media controlled by Real-time Streaming Protocol (RTSP)
	Author(s)       : M. Westerlund, T. Zeng
	Filename        : draft-ietf-mmusic-rtsp-nat-evaluation-01.txt
	Pages           : 37
	Date            : 2008-07-11

This document describes several NAT traversal techniques that could
be used by RTSP.  Each technique includes a description on how it
would be used, the security implications of using it and any other
deployment considerations it has.  There are also disussions on how
NAT traversal techniques relates to firewalls and how each technique
can be applied in different use cases.  These findings where used
when selecting the NAT traversal for RTSP solution to standardize in
the MMUSIC WG.Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-mmusic-rtsp-nat-evaluation-01.txt

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ftp://ftp.ietf.org/internet-drafts/

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From: Rémi Denis-Courmont <[email-masked]>
Date: Fri, 11 Jul 2008 17:13:10 +0300

On Friday 11 July 2008 15:00:02 ext [email-masked], you wrote:
> 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.

This new version seems quite good (not to say that the previous was bad) to 
me.

One thing about ALGs: the most likely (and least stupid) implementation is to 
look for the "right" (internal) IP/port, at the right place (in the SETUP 
Transport header) and replace them with the "right" (external) IP/port. If 
done so, it will not break any of the proposed mechanism.

I agree that some pretty stupid ALG could break STUN if they replace 
the "wrong" IP/port at the "right" place regardless. Another case is the even 
stupider ALG that replaces the "right" IP/port at the "wrong" place (i.e. 
anywhere it can find it). I believe this would screw up ICE local candidates, 
though I guess ICE should still work. It should have no effect on other 
mechanisms.

As with the comparison table... It seems that the STUN-RTSP-combined server 
case is missing?

-- 
Rémi Denis-Courmont
Maemo Software, Nokia Devices R&D
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From: Magnus Westerlund <[email-masked]>
Date: Mon, 14 Jul 2008 13:29:13 +0200

> done so, it will not break any of the proposed mechanism.

Are you talking about finding already existing mappings if they exist, 
or to create new mappings and introducing them correctly?

I think you are mostly correct. However, there is still the risk that to 
strict checks in some solutions could result in the using of another 
working binding than what the client server tested results in failure.

> though I guess ICE should still work. It should have no effect on other 

Yes.

> As with the comparison table... It seems that the STUN-RTSP-combined server 

You are correct, I will put it in in the next version.

Thanks

Magnus Westerlund

IETF Transport Area Director & TSVWG Chair
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