Re: [Dime] Alissa Cooper's Discuss on draft-ietf-dime-drmp-05: (with DISCUSS and COMMENT)

Alissa Cooper <> Thu, 05 May 2016 04:36 UTC

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From: Alissa Cooper <>
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Date: Wed, 04 May 2016 21:31:29 -0700
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To: Stephen Farrell <>
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Subject: Re: [Dime] Alissa Cooper's Discuss on draft-ietf-dime-drmp-05: (with DISCUSS and COMMENT)
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> On May 4, 2016, at 11:53 AM, Stephen Farrell <> wrote:
> Hiya,
> Please do continue the discussion all, but just on one aspect of
> this...
> On 04/05/16 19:18, Alissa Cooper wrote:
>> Even if only a single application ever defines a priority scheme, a 
>> network where clients can’t be trusted could fall victim to an 
>> attacker who inflates the priority of his traffic to try to prevent 
>> emergency calls/first responders from getting priority treatment.
> My understanding of Diameter deployments is that they are pretty
> much all done so that any node can play all sorts of games and
> there are no protocol mechanisms other than hop-by-hop TLS or IPsec
> to control that. I'm not even sure how much those are deployed, even
> in cases where cryptographic keys are passed in Diameter messages.
> (And that's when the base protocol spec says you MUST use TLS in
> such cases. [1])
> So DRMP and DOIC are by far not the most attractive target here.

But my point was specifically about how the motivation for DRMP is tied to the first responder and emergency use cases. When a capability is defined specifically for those uses, people (or, say, regulators) tend to expect it to work. So if there is a class of cases where it won’t work at all — even if the net effect is just that requests get treated on a best efforts basis the same as they do today, not that some requests get starved — it’s worth being very explicit about that. I’m sure there are other attacks that could target these uses in the absence of DRMP, but that isn’t a reason to gloss over the DRMP-specific issue in this spec.


> The DIME WG are attempting to address that via [2] but I'm not
> sure if we ought be hugely hopeful of that being implemented
> or deployed either.
> It might help if someone more familiar with deployments can
> correct or confirm the above.
> That doesn't affect the issue of potentially un-coordinated uses
> of different priorities across multiple Diameter applications,
> which seems like it is worth saying more about, but I'd have to
> say that uses of DRMP as an attack vector aren't that compelling
> from what I know, and the WG are attempting to at least document
> mechanisms that would provide relevant protocol countermeasures
> for the base protocol.
> Cheers,
> S.
> [1]
> [2]