Subject: [Add] draft-arkko-abcd-distributed-resolver-selection

From: Ted Hardie <[email-masked]>
Date: Tue, 25 Feb 2020 10:00:51 -0800

Howdy,

Jari, Martin, and I put together
draft-arkko-abcd-distributed-resolver-selection
<https://datatracker.ietf.org/doc/draft-arkko-abcd-distributed-resolver-selection/?include_text=1>
to
start a discussion on whether DNS clients can improve their privacy through
the use of a set of multiple recursive resolver services.  We think it
might be in scope for ADD, since the charter says the group "will focus on
discovery and selection of DNS resolvers" and this discusses the impact of
selecting more than one.

Do the chairs and the working group agree?  If so, can we ask for agenda
time at IETF 107 to present?

thanks,

Ted

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From: Eric Rescorla <[email-masked]>
Date: Tue, 25 Feb 2020 13:05:29 -0800

I'd be interested in seeing a presentation on this. I don't really agree
with much of the analysis but I believe the topic is relevant.

-Ekr

On Tue, Feb 25, 2020 at 10:01 AM Ted Hardie <[email-masked]> wrote:

> <https://datatracker.ietf.org/doc/draft-arkko-abcd-distributed-resolver-selection/?include_text=1> to
> --
> Add mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/add
>

---

From: Adam Roach <[email-masked]>
Date: Tue, 25 Feb 2020 15:20:37 -0600

Not relating to the question at hand as much as the contents -- it's 
probably useful in any treatment of this topic to include a discussion 
of how to handle additional records. E.g., if the query distribution 
algorithm would ordinarily query server A for record X, but has already 
received record X as additional information from server B, what behavior 
would we recommend?

(A simple analysis would say to use the already-received information, 
since it minimizes transmission of queries altogether.)

/a

On 2/25/2020 12:00 PM, Ted Hardie wrote:
> to start a discussion on whether DNS clients can improve their privacy 
> through the use of a set of multiple recursive resolver services.  We 
> think it might be in scope for ADD, since the charter says the group 
> "will focus on discovery and selection of DNS resolvers" and this 
> discusses the impact of selecting more than one.
>
> Do the chairs and the working group agree?  If so, can we ask for 
> agenda time at IETF 107 to present?
>
> thanks,
>
> Ted
>

---

From: Erik Kline <[email-masked]>
Date: Tue, 25 Feb 2020 13:26:27 -0800

I think section 4 (maybe) could have some discussion of per-app based
resolver selection.

Mobile operating systems can sometimes have more data about which apps are
making which queries than, say, general Unix-derived OSes.

Also, with DoH, this might be something that can be chosen/randomized by
the webpage itself (e.g. on a per-service-worker basis or something; /me
handwaves in W3C).

---

From: Stephen Farrell <[email-masked]>
Date: Tue, 25 Feb 2020 21:56:44 +0000

Hiya,

On 25/02/2020 21:05, Eric Rescorla wrote:
> I'd be interested in seeing a presentation on this. 

+1

> I don't really agree

I suspect this is an area where some good new ideas may
be needed to make progress.

On the draft itself, the set of available recursives is
often not the same as the set of configured/potential
recursives, in my experience mainly because of IPv4/IPv6
and blocking of 853. e.g. when I'm on the TCD college
n/w (during office-ish hours:-) 853 is blocked and IPv6
only works on the wireless interface, etc. All of that
could skew the output of any selection algorithm with
relatively long cycle durations.

Cheers,
S.

---

From: Vittorio Bertola <[email-masked]>
Date: Wed, 26 Feb 2020 11:20:35 +0100 (CET)

>     Il 25/02/2020 19:00 Ted Hardie <[email-masked]> ha scritto:
> 
> 
>     Howdy,
> 
>     Jari, Martin, and I put together draft-arkko-abcd-distributed-resolver-selection https://datatracker.ietf.org/doc/draft-arkko-abcd-distributed-resolver-selection/?include_text=1 to start a discussion on whether DNS clients can improve their privacy through the use of a set of multiple recursive resolver services.  We think it might be in scope for ADD, since the charter says the group "will focus on discovery and selection of DNS resolvers" and this discusses the impact of selecting more than one. 
> 
This is another idea that looks great from a purely technical standpoint but a total nightmare in terms of policy, both public and local, both legal and technical (e.g. network security). Also, it only increases privacy if by privacy you mean spreading your data as much as possible among many parties, but not if (as per the GDPR's data minimization principle) by privacy you mean minimizing the amount of data you give away and the number of parties who know something about you - let alone the discussion on whether this model in the end would lead to more or less centralization in terms of DNS providers.

For example, if the client, rather than using a single resolver in its own country that offers reasonable privacy guarantees, spreads its queries among N resolvers that are all or almost all run under a single foreign jurisdiction, this creates an additional risk for surveillance by that country's national security agencies that did not exist before, and that might outweigh any advantage gained by spreading the queries across multiple resolvers.

This said, of course I'm fine with a presentation, but I challenge the draft's conclusion that these strategies are "generally beneficial in the common cases". If this ever becomes a working item, the analysis should cover all the pros and cons and the discussion should go well beyond the IETF to understand the conditions for doing this that would make all stakeholders happy (like it should have been done with DoH).

--

Vittorio Bertola | Head of Policy & Innovation, Open-Xchange
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