Dan,

>there is high comfort in the working group that proxies and SBCs do not

>go rogue.

This is really not surprising given that nobody in the meeting was
prepared to report on _measured_ incidents vs. voicing opinions.

I share your concern since a stateful SBC, that also handles media is
the ideal target for evil doers on the Internet. Where else would
someone intercept phone calls and the signaling, all conveniently in one
place?

Now with peering, a questionable chain of trust develops that is even
more likely to break.

If there were only a way to collect incident reports...

But maybe we are barking up the wrong tree: The purpose here is not
security but usage billing and whenever possible, collecting roaming
charges.

Henry

-----Original Message-----
From: Dan Wing [mailto:[EMAIL PROTECTED] 
Sent: Monday, August 13, 2007 6:10 PM
To: 'Dean Willis'; 'sip List'
Cc: 'Sandy Murphy'
Subject: RE: [Sip] Question on SIP Security considerations for
futureextensions

...
> what do you folks think?
> 
> 1) Could a reasonable "How you could be violated by trusted proxies  
> that turn rogue" boilerplate be drafted?
> 2) Would the practice of repeating this in drafts help or hurt us?
> 3) Would it be useful for us to document how each extension could be  
> used by a rogue proxy?

In Chicago when I presented draft-wing-sip-identity-media, Cullen
said transitive trust of the entire SIP network for Identity was 
fine, and RFC4474 was sufficient even with SBCs in the network.  At 
the meeting, only Hadriel Kaplan said transitive trust for identity 
was not desirable with SBCs in the network.  If identity can be 
spoofed by any trusted proxy in the SIP network you're connected 
to, you're going to be unable to gain strong identity that's needed 
for sip-answermode (defense mechanism #1 identified in section 7.3
of draft-ietf-sip-answermode-04) or even the strong identity needed
to reliably display Caller-ID.

However, based on the tepid response to sip-identity-media in
Chicago, my conclusion is there is high comfort in the working 
group that proxies and SBCs do not go rogue.

I found this surprising, and I continue to find this surprising.


To your questions, I think such text would be valuable, but to
really be useful we'd need an I-D that analyzed RFC3261 itself
under the same microsocope.  Such a document could start with
the examples from your original post.

-d


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