Re: [DNSOP] I-D Action: draft-ietf-dnsop-refuse-any-04.txt

Vernon Schryver <vjs@rhyolite.com> Mon, 13 February 2017 22:43 UTC

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Date: Mon, 13 Feb 2017 22:43:23 GMT
From: Vernon Schryver <vjs@rhyolite.com>
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Subject: Re: [DNSOP] I-D Action: draft-ietf-dnsop-refuse-any-04.txt
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> From: Tony Finch <dot@dotat.at>

> One of the points of minimal-any is that the answer is not truncated
> because you do not want clients to automatically retry over TCP. This is
> to handle situations where many third-party recursive servers are under
> attack using one of your names, so the recursive servers are hitting
> your authoritative servers hard. RRL does not work in this case, because
> the clients are legitimate recursive servers. You want to give them an
> answer asap, that they can cache without hitting TCP.

On the contrary, as that case is described, RRL works fine, and
this minimal-any mechanism won't help the obvious attack situation
in that might be intended.

Each legitimate recursive server will ask once per some TTL and
cache the rrsets that it gets.  No single legitimate recursive
server will make a lot of ANY requests per unit time.

An attack that might be intended involves many open recursive servers
(perhaps open only local infected eyeball stubs) being hit for only a
few requests each (or at least passing on only a few each request) for
your names but many all together.

However, in that case how many legitimate recursive servers will
send ANY requests to authorities?


Vernon Schryver    vjs@rhyolite.com