Re: [rtcweb] Consent alternative

"Muthu Arul Mozhi Perumal (mperumal)" <mperumal@cisco.com> Wed, 04 December 2013 05:08 UTC

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From: "Muthu Arul Mozhi Perumal (mperumal)" <mperumal@cisco.com>
To: Martin Thomson <martin.thomson@gmail.com>
Thread-Topic: [rtcweb] Consent alternative
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Date: Wed, 4 Dec 2013 05:08:01 +0000
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Cc: "Cullen Jennings \(fluffy\)" <fluffy@cisco.com>, "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] Consent alternative
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|I think that you have missed the point here. The point is that A and
|B share a DTLS connection, and B uses ICE to convince A to send
|packets for that connection to C. 

Can you describe that in terms of a real-world use case? I don't see how that is different from a 3PCC scenario where the 3PCC (e.g a call center agent) talks to both A and C, and transfers A to C (aka full-consult transfer). 

|All this requires is that B is able to spoof the source address of 
|packets to appear as coming from C.

B doesn't have to spoof anything at all -- for the ICE connectivity check to succeed b/w A and C, B just needs to send A's ice-ufrag and ice-pwd to C and vice versa.

Muthu

|-----Original Message-----
|From: Martin Thomson [mailto:martin.thomson@gmail.com]
|Sent: Tuesday, December 03, 2013 10:25 PM
|To: Muthu Arul Mozhi Perumal (mperumal)
|Cc: rtcweb@ietf.org; Magnus Westerlund; Cullen Jennings (fluffy)
|Subject: Re: [rtcweb] Consent alternative
|
|On 3 December 2013 04:48, Muthu Arul Mozhi Perumal (mperumal)
|<mperumal@cisco.com> wrote:
|> That's a typical third party call control (3PCC) use case where B (3PCC)
|> mangles call signaling + SDP b/w A and C and sets up the media session
|> between them. The security of ICE (as defined in RFC5245) is rooted in the
|> ice-ufrag and ice-pwd exchanged in call signaling. If a 3PCC can mangle
|> them, ICE can't prevent the connectivity check from succeeding.
|>
|>
|>
|> If it is deemed a problem, it might need an ICE extension to fail the
|> connectivity check b/w A and C.
|
|I think that you have missed the point here.  The point is that A and
|B share a DTLS connection, and B uses ICE to convince A to send
|packets for that connection to C.  All this requires is that B is able
|to spoof the source address of packets to appear as coming from C.
|It's got nothing to do with 3PCC scenarios.