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Re: [dns-privacy] ADoT signalling

Stephane Bortzmeyer <bortzmeyer@nic.fr> Mon, 04 November 2019 15:32 UTC

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Date: Mon, 04 Nov 2019 16:32:26 +0100
From: Stephane Bortzmeyer <bortzmeyer@nic.fr>
To: Eric Rescorla <ekr@rtfm.com>
Cc: Stephane Bortzmeyer <bortzmeyer@nic.fr>, John Levine <johnl@taugh.com>, dns-privacy@ietf.org
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Subject: Re: [dns-privacy] ADoT signalling
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On Mon, Nov 04, 2019 at 07:12:46AM -0800,
 Eric Rescorla <ekr@rtfm.com> wrote 
 a message of 96 lines which said:

> I'm less worried about the latter because I would expect recursive
> resolvers to generally be operated by people who are able to
> establish their port 853 status.

Not all resolvers are big boxes in the central datacenter. I may want
to run a resolver on a small box at home even if my ISP blocks port
853.

> Well, this is why I asked about the threat model. If we care about
> active attack, then this kind of approach does not work well.

I tend to agree with Stephen Farrell here. If we insist on perfect
resistance to active attackers, we may never deploy anything. I would
suggest something more like "probe 853, remember what it was last time
(to warn the sysadmin about a sudden block), may be allow to whitelist
auth servers that must have DoT".

For signaling, my personal preference goes to DANE, anyway.

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