Re: [DNSOP] draft-ietf-dnsop-refuse-any and QTYPE=RRSIG

Ólafur Guðmundsson <olafur@cloudflare.com> Sat, 06 February 2016 00:56 UTC

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Date: Sat, 06 Feb 2016 00:56:14 +0000
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From: Ólafur Guðmundsson <olafur@cloudflare.com>
To: Tony Finch <dot@dotat.at>
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Subject: Re: [DNSOP] draft-ietf-dnsop-refuse-any and QTYPE=RRSIG
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On Fri, Feb 5, 2016 at 10:10 PM, Tony Finch <dot@dotat.at> wrote:

> Last weekend one of our authoritative name servers
> (authdns1.csx.cam.ac.uk) suffered a series of DoS attacks which made it
> rather unhappy. Over the last week I have developed a patch for BIND to
> implement draft-ietf-dnsop-refuse-any which should allow us to handle
> ANY flood attacks better. http://fanf.livejournal.com/140566.html
>
> I still have a potential problem with RRSIG queries, which work a lot like
> ANY queries. Cloudflare's approach is to simply refuse them, which makes a
> lot of sense because RRSIG queries don't have the same interop concerns as
> ANY queries. However, in an attack like the ones we had last weekend where
> the queries arrived at our authoritative servers from lots of real
> recursive servers, a refusal will cause retries and make the attack worse.
>
> Would it be reasonable as an alternative to follow the refuse-any approach
> and just return the RRSIG(s) for one RRset? If so, I think this suggestion
> should be included in the draft.
>
>
For all you care you an even return a forged RRSIG/SIG i.e. one that is
made up on the fly
just make sure it covers a non existing TYPE :-)

   Olafur