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Re: [DNSOP] Stupid thought: why not an additional DNSKEY record flag: NSEC* only...

Mukund Sivaraman <muks@isc.org> Wed, 04 January 2017 18:45 UTC

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Date: Thu, 05 Jan 2017 00:15:52 +0530
From: Mukund Sivaraman <muks@isc.org>
To: Nicholas Weaver <nweaver@icsi.berkeley.edu>
Message-ID: <20170104184552.GA31138@jurassic>
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Subject: Re: [DNSOP] Stupid thought: why not an additional DNSKEY record flag: NSEC* only...
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On Wed, Jan 04, 2017 at 10:28:11AM -0800, Nicholas Weaver wrote:
> An attacker in that position can just put in garbage, and you get
> SERVFAIL instead of NXDOMAIN, regardless of whether the attacker has
> compromised the key or not.

A SERVFAIL is an erroneous condtion. An NXDOMAIN is not - it is business
as usual. SERVFAILs are sometimes cached very temporarily to reduce load
on upstream servers, but they are not answers. NXDOMAINs are cached as
*answers* from the remote auth server.

On-path disruption is impossible to defeat. An on-path attacker who
wants to poison answers without raising suspicions (logged validation
failures) will want validation to succeed.

		Mukund

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