Re: [Doh] Servers offering responses for domaines they are not responsible for

Eliot Lear <lear@cisco.com> Thu, 09 November 2017 10:46 UTC

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To: Andrew Sullivan <ajs@anvilwalrusden.com>, doh@ietf.org
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From: Eliot Lear <lear@cisco.com>
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Date: Thu, 9 Nov 2017 16:16:37 +0530
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Subject: Re: [Doh] Servers offering responses for domaines they are not responsible for
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Hi Andrew,


On 11/6/17 5:37 PM, Andrew Sullivan wrote:
> On Mon, Nov 06, 2017 at 08:25:17AM +0100, Eliot Lear wrote:
>> It is a *a* remedy, and could certainly be mentioned.  However,
>> precisely because of the warnings in that document, it probably
>> shouldn't be listed on its own as the sole recommended approach.
> It's the only thing we have that solves this problem today, however.
> If you want geo- or even (and more accurately) network-topologically
> sensitive answers to work, you need to know where the query originator
> was.  For years we used the network address of the resolver as a proxy
> for the location of the query originator, but in a world where
> resolvers may be quite distant from the query originator that doesn't
> work, and it doesn't matter whether the query travels via UDP port 53
> or some other mechanism.
>
> And indeed, given the DOH use case (which as we're currently
> discussing it is really just last hop), I'm not sure what the problem
> is.  This is directly analagous to a stub contacting a full service
> resolver, and that's exactly the problem the large authoritative DNS
> tricks have and that edns-client-subnet addresses.

Having thought about this a bit, what got me was this:

1.  I get the impression through my own experience that it doesn't seem
to be used (I see odd localizations that could have been avoided were it
so); and
2.  Given that, DOH can exacerbate the problem if the service is not
deployed as a CDN itself.

So I think Mark's right to out the remediation.  I just am wary that
it's enough.

Eliot



>
> Best regards,
>
> A
>