Re: [DNSOP] Robert Wilton's No Objection on draft-ietf-dnsop-dns-zone-digest-12: (with COMMENT)

John Levine <johnl@taugh.com> Sat, 10 October 2020 15:34 UTC

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From: "John Levine" <johnl@taugh.com>
To: dnsop@ietf.org
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Subject: Re: [DNSOP] Robert Wilton's No Objection on draft-ietf-dnsop-dns-zone-digest-12: (with COMMENT)
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In article <20201010032517.GM89563@kduck.mit.edu> you write:
>There's two general classes of attack to consider: when an external
>attacker takes an existing ZONEMD and tries to modify the associated zone,
>or when the zone provider is the malicious entity that wants to provide
>different content to different people but give them the same digest value ...
 
I think there's a third threat, a transcription error due to
transmission error or other kinds of bitrot. I send zone files between
my DNS servers over ssh, so the chances of an external attack are low,
but particularly as zone files continue to grow, the protection of the
TCP checksum is less effective. On my rather small DNS setup I have a
71MB zone and I don't think that's unusual. In many, probably most,
cases a bit flip or two would produce DNS data that is still valid but
wrong, e.g., change the address in AAAA or the characters in a name
anywhere.

That's why there are situations where a zone digest can be useful
even without a DNSSEC validation chain.

R's,
John