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Re: [dane] Behavior in the face of no answer?

Tony Finch <dot@dotat.at> Tue, 08 May 2012 19:41 UTC

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Date: Tue, 8 May 2012 20:41:48 +0100
From: Tony Finch <dot@dotat.at>
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To: Yoav Nir <ynir@checkpoint.com>
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Cc: Adam Langley <agl@imperialviolet.org>, "dane@ietf.org" <dane@ietf.org>
Subject: Re: [dane] Behavior in the face of no answer?
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Yoav Nir <ynir@checkpoint.com> wrote:
>
> I can think of a heuristic for this. Suppose we have to domain names,
> one with a valid TLSA record, the other without. The browser could query
> the DNS for a TLSA record for both of these, and if both answers are
> received, then TLSA works. In that case, a timeout can rightfully become
> a hard fail. If no response is received to either query, then either the
> DNS is broken or the attack is already going on. In that case the user
> should be warned with the likelier of the two - that the DNS seems to be
> broken, and certain kinds of attack are possible.

I think the "DNSSEC works but TLSA doesn't" heuristic may also be useful.

Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>  http://dotat.at/
Lundy, Fastnet, Irish Sea: Variable 3 or 4 becoming northeast 4 or 5,
occasionally 6 later. Slight or moderate. Rain or showers. Good, occasionally
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