Re: [tcpm] tcp-security: Request for feedback on the outline of the document

Joe Touch <touch@ISI.EDU> Sun, 30 August 2009 17:24 UTC

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Date: Sun, 30 Aug 2009 10:24:18 -0700
From: Joe Touch <touch@ISI.EDU>
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Subject: Re: [tcpm] tcp-security: Request for feedback on the outline of the document
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Fernando Gont wrote:
> Joe Touch wrote:
>>> The various past reviewers of the original document had
>>> appreciated the focus on implementer's point of view,...
>> This is a good point. This isn't just an implementer's guide, however.
>> Some of the issues are being discussed in detail for the first time in
>> this doc.
> The latter is true, but the document is still meant to target
> implementers. If you spread the advice on a per-attack basis, or on a
> protocol-weaknesses vs. implementer's-choice-weaknesses, you're
> basically spreading the advice about a single protocol field or option
> among multiple sections.

Maybe - some fields are susceptible to only a small set of attacks that
may be related. However, we'd also be allowing (if not encouraging) use
of protections as appropriate, rather than encouraging everyone to
implement every protection - some of which are not agreed as recommended
by the WG.

>> Some of the ways to address vulnerabilities are choices that the specs
>> left open to implementers. Some are weaknesses in the protocol itself
>> that a clever implementation can overcome (e.g. SYN cookies to overcome
>> the state introduced at SYN receipt). Others are created by inefficient
>> implementations (e.g., badly implemented TIME-WAIT state lists).
> What's the difference in here? Are we concerned about "who gets the blame"?

This doc isn't only useful to implementers. People developing specs care
about #1 - maybe these are holes to be filled. #2 can result in
interactions between the solution and the protocol that were unintended.
#3 is just good design.

An implementer needs to know when they're playing inside a box the spec
created (#1), playing around in ways that could affect the protocol now
or in the future (#2), or just need to apply known algorithms rather
than modify the protocol.

>> In the submitted I-D, protocol field properties are covered in sections
>> 3,5,8,9,11,13,14,15. 
> I disagree. Protocol field properties are covered in Sections 3 and 4.
> e.g., Sections 5 through 9 cover specific mechanisms or policies, but
> not the fields themselves.

Well, I found 8 places. You found 2 places at least, if not another 2
for a total of 4 (I don't care whether it's a mechanism or policy, if it
affects the field).

The point is that in the outline proposed in ID-0, there are multiple
top-level sections where these issues are discussed. The idea that "an
implementer wants to find things in one place" is fine, but IMO the
outline I proposed may to a mode useful job of aggregating this
information than ID-0.

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