Re: [Doh] Dedicated DoH port

Petr Špaček <petr.spacek@nic.cz> Fri, 12 April 2019 10:15 UTC

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To: Daniel Kahn Gillmor <dkg@fifthhorseman.net>, doh@ietf.org
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Date: Fri, 12 Apr 2019 12:16:31 +0200
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Archived-At: <https://mailarchive.ietf.org/arch/msg/doh/2ULw7PX-MeXQZtNkt_KeVufwl3Q>
Subject: Re: [Doh] Dedicated DoH port
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On 11. 04. 19 21:23, Daniel Kahn Gillmor wrote:
> On Thu 2019-04-11 19:41:42 +0200, Tomas Krizek wrote:
>> Service Name:         [domain-doh]
>> Desired Port Number:  [44353]
>> Description:          [DNS query-response protocol over HTTPS]
> 
> i agree with other commenters that this seems like it might not a useful
> allocation for a number of reasons.
> 
> For knot-resolver specifically, i'd much rather it ship with DoH
> disabled by default.

Can you elaborate on the reasons, please?

Do you oppose enabling DoT by default as well?

It utterly confuses me that this very WG on one hand invented DoH
protocol because DoT is not good enough, but then WG participants claims
it should not be enabled by default.

> In terms of integration into a modern GNU/Linux system, an interested
> admin can do "systemctl enable kresd-doh.socket" to turn it on on port
> 443.  Or, you could imagine providing a separate OS-level
> "knot-resolver-doh" package that depends on knot-resolver, supplies the
> necessary module and .socket unit file, and explicitly conflicts with
> the other OS-level packages that would typically listen on port 443.
> 
> Either of these solutions seems better to me (and easier for an
> administrator) than establishing a distinct TCP port for DoH.

Can you elaborate? I do not understand where "easiness" of manual
configuration comes from. Here my reasoning on this topic:

Current state of DoH protocol is that it requires manual configuration
on all clients. In near future it is going to rely on hardcoded values
from browser vendor. I.e. actual hostname and port number are irrelevant
because admin (or vendor) has copy&paste then anyway.

Draft
https://tools.ietf.org/html/draft-ietf-doh-resolver-associated-doh-03
might be different story if WG decides to go with solutions other than
section 3, but honestly it seems that draft is not going to get
consensus any time soon.

My reading of this mailing list indicates that there is strong
opposition to any insecure means of discovery, which renders the draft
useless and we are back to copy&pasted or hardcoded values.


So, how is it easier to copy&paste or hardcode
https://doh.example.com/doh
vs.
https://doh.example.com:44353/doh
?

Having dedicated port could allow us to do everything automatically so
only copy&paste is left for admin. Default on port used by other
services requires even more manual manual configuration, which goes
against idea of having as many resolvers available as we can, with as
little effort as possible.

So, why should we make it harder for admins to make it available?

I'm eager to hear reasons.
-- 
Petr Špaček  @  CZ.NIC