Re: [secdir] Secdir review of draft-ietf-multi-cost

"Randriamasy, Sabine (Nokia - FR/Nozay)" <> Mon, 27 March 2017 23:36 UTC

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From: "Randriamasy, Sabine (Nokia - FR/Nozay)" <>
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Thread-Topic: Secdir review of draft-ietf-multi-cost
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Date: Mon, 27 Mar 2017 23:36:01 +0000
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Subject: Re: [secdir] Secdir review of draft-ietf-multi-cost
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Hello Magnus,

Thank you very much for your review and feedback. To answer your questions:
- we believe that this proposal does not cause any additional security issues compared to the base protocol specified in RFC7285. The Multi-Cost optimization even tends to reduce the  on the wire data exchange volume compared to multiple single cost ALTO transactions. Likewise, the risk related to massive multi-cost request is moderated by the fact that Multi-Cost constraints further filters ALTO Server responses and thus their volume. 
- Indeed the formulation "legacy" needs be updated as you suggest. We will track similar examples and post a revision. 

Best regards,

>>-----Original Message-----
>>From: Magnus Nyström []
>>Sent: lundi 27 mars 2017 05:51
>>Subject: Secdir review of draft-ietf-multi-cost
>>I have reviewed this document as part of the security directorate's ongoing
>>effort to review all IETF documents being processed by the IESG. These
>>comments were written primarily for the benefit of the security area
>>directors. Document editors and WG chairs should treat these comments just
>>like any other last call comments.
>>This document describes extensions to the ALTO (Application Layer Traffic
>>Optimization) protocol that allows for more efficient information exchanges
>>between an ALTO client and an ALTO server.
>>Specifically, it allows a client to query for multiple metrics in one request.
>>The security considerations section correctly refers to the basic ALTO
>>protocol I only have one additional consideration (and I don't even know if it
>>applies ...): With the existing ALTO protocol, a server could defend against
>>dDOS by not throttling requests. However, each accepted request is simple
>>in that it only deals with one metric. With this document, a malicious client
>>could send a highly complicated query to the server, which may cause
>>significant resources to be used on the server end and without an ability to
>>throttle. Is that a risk?
>>Other than that, the document may benefit from a language/grammar
>>review. Example:
>>"Hence a legacy may send a request with a constraint test on any of the cost
>>types listed in "cost-type-name" - should likely be "legacy client". There are
>>more such examples.
>>-- Magnus