Re: [DNSOP] extension of DoH to authoritative servers

Bjørn Mork <> Thu, 14 February 2019 12:12 UTC

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From: Bjørn Mork <>
To: Vladimír Čunát <>
Cc: "" <>, Shane Kerr <>
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Date: Thu, 14 Feb 2019 13:11:55 +0100
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Subject: Re: [DNSOP] extension of DoH to authoritative servers
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Vladimír Čunát <> writes:

> You can still multiplex based on SNI sent by the client.  HTTPS clients
> surely send it commonly.  DoT clients perhaps not so often, but that's
> just an implementation detail (which I was fixing in the past few weeks
> in knot-resolver, incidentally).

My understanding of the reference to BCP195 from
is that SNI support is required for all DoT implementations.

> I'm not sure how easy SNI-based multiplexing is to configure with
> nowadays software, but I believe I've heard of some such setup with
> nginx.  And I don't have any idea whether SNI encryption would interfere
> with that, but I hope not.  ESNI will be a key part of DNS privacy,
> though mainly for the non-DNS traffic.

It's simple to do with haproxy at least:

...which incidentally also can be used to support DoT with *any* DNS
server as backend.