Subject: [dns-privacy] Alexey Melnikov's No Objection on draft-ietf-dprive-bcp-op-08: (with COMMENT)

From: Alexey Melnikov via Datatracker <[email-masked]>
Date: Thu, 06 Feb 2020 08:52:19 -0800

Alexey Melnikov has entered the following ballot position for
draft-ietf-dprive-bcp-op-08: No Objection

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COMMENT:
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I think this is a very useful document and I am looking forward to it getting
published.

I support updated Ben’s DISCUSS.

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The following comments were provided by Benjamin Schwartz <[email-masked]>:

Benjamin would have balloted *DISCUSS* on this document. He wrote:

This draft is close to ready, but it contains some elements that are not
appropriate for IETF publication or lack IETF consensus.

## Section 1

Typo: “For example the user has a clear expectation of which resolvers have
visibility of their query data however this...” -> Add a period before
“however”.

Inappropriate subject matter:

    It is an untested area that simply using a DNS
    resolution service constitutes consent from the user for the operator
    to process their query data.

This is legal speculation, not appropriate for IETF.  Strike this sentence.

Clarity:

    Privacy considerations specifically
    from the perspective of an end user ... are out of scope.

This seems confusing as written: surely it is the privacy of end users (and not
of resolver operators) that this draft seeks to protect.  Please rephrase or
omit this disclaimer.

## Section 5.1

Version skew: dprive-rfc7626-bis no longer has a Section 2.4.2 or 2.5.3.

## Section 5.1.2

Clarity: Redirection of traffic to rogue servers does not match the usual
definition of “surveillance”.  I would suggest adding an explanation of how
this active attack is a privacy threat.  Presumably you are referring to merely
intercepting the user’s DNS queries, as opposed to substituting modified DNS
responses in order to monitor post-DNS network activity, but the text is not
clear on this distinction.

## Section 5.1.3.1

Current practices:  I don’t think either EDNS(0) Keepalive or DNS Stateful
Operations is currently in use with DNS-over-TLS, so this recommendation seems
too strong for a BCP.  For example, this could say “Management of TLS
connections as described in RFC 7766.  EDNS(0) Keepalive and DNS Stateful
Operations may provide additional performance benefits.”

Scope: The optimizations here are performance optimizations, which seem out of
place in this document.  I would suggest focusing the document on “Encrypted
DNS Service Privacy Recommendations”, and remove any recommendations related to
performance and reliability, which are already well-covered by standards-track
RFCs.

## Section 5.2.1

Content: I think there’s a missing mitigation here, which is employed virtually
universally among large DNS Privacy deployments: IP erasure.  DNS operators
typically distinguish between PII-logs, which are retained at most briefly, and
non-PII logs, which are retained for a longer period.  I believe this is a best
practice and worth documenting.

## Section 5.3.1

Document interaction: This section comes awfully close to updating or
deprecating ECS, which we do not have IETF consensus for.  I think the BCP here
should restrict itself to disclosing the server’s ECS behavior and imposed
prefix length limit.

## Section 6.1.1

Terminology: “PII” appears here for the first time, and is not defined.