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Re: [DNSOP] I-D Action: draft-ietf-dnsop-aname-01.txt

Evan Hunt <each@isc.org> Sat, 03 February 2018 22:10 UTC

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Date: Sat, 03 Feb 2018 22:10:46 +0000
From: Evan Hunt <each@isc.org>
To: Stefan Bühler <ietf-dnsop@stbuehler.de>
Cc: dnsop@ietf.org
Message-ID: <20180203221046.GA8571@isc.org>
References: <151573473976.18703.16142464801623244164@ietfa.amsl.com> <102bc41e-d2cf-e184-4bec-b1fdf945ae3e@stbuehler.de> <20180126200942.GA7808@isc.org> <29db47a4-2355-2eae-de68-b4bb18b4ebaf@stbuehler.de>
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Subject: Re: [DNSOP] I-D Action: draft-ietf-dnsop-aname-01.txt
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On Sat, Feb 03, 2018 at 12:20:34PM +0100, Stefan Bühler wrote:
> This advise suggests that if the auth server has access to the zone's
> private key and can sign responses on the fly, ANAME works with signed
> zones.
>
> But it doesn't!  Because ANAME-aware recursive resolvers will replace
> the signed records with unsigned ones.

No, an ANAME-aware resolver would ignore those records, re-query for
the ANAME target, and validate the response from there - same as it does
now with a CNAME. As long as the ANAME is validly signed, it's just a
chain query.

> I'd also suggest to relax the "MUST re-query" requirement if the
> resolver used ECS - because it means the auth server had a good chance
> to respect the network topology (this is unrelated to signed zones).

It's the same requirement as for CNAME. Putting full trust in a chain
returned by an auth server risks cache poisoning. (Not even necessarily
malicious; the auth might simply be serving information that's outdated.)

-- 
Evan Hunt -- each@isc.org
Internet Systems Consortium, Inc.

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