Subject: [dnssd] Barry Leiba's Yes on draft-ietf-dnssd-prireq-05: (with COMMENT)

From: Barry Leiba via Datatracker <[email-masked]>
Date: Tue, 25 Feb 2020 17:06:32 -0800

Barry Leiba has entered the following ballot position for
draft-ietf-dnssd-prireq-05: Yes

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COMMENT:
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It’s useful to have this analysis; thanks.  Just some editorial comments below.
 Please consider them; none needs any explicit response.  Please take specific
note of the last one, about the references.

General: “i.e.” and “e.g.” always need a comma after them.

— Section 1 —

   There are cases when nodes connected to a network want to provide or
   consume services without exposing their identity to the other parties

Nit: “their identities” (or “a node… wants… its identity”)

   Consider for example a traveler

Nit: “Consider, for example, a traveler”

   Disclosing Information  In this document "disclosing information" is
      also focused on disclosure by data conveyed via messages on the
      service discovery protocol layer.

Do you mean “disclosure of data” (not “by”)?

— Section 2 —

   All these attackers can either be passive, i.e.
   they just listen to network traffic they have access to, or active,
   i.e. they additionally can craft and send (malicious) packets.

Style: You decide, of course, but I find this easier to read with parentheses,
rather than “i.e.”s:

SUGGEST
   All these attackers can either be passive (they
   just listen to network traffic they have access to) or active
   (they additionally can craft and send malicious packets).
END

   on-link  An on-link attacker is on the same network link as victim
      devices engaging in service discovery; thus, the external attacker
      is in the same multicast domain.

The second line should say “on-link attacker”.

   MITM  A Man in the Middle (MITM) attacker either controls (parts of)
      a network link or can trick two parties to send traffic via him;

Nit: “Man-in-the-Middle” needs hyphens when it modifies “attacker”.
Style: I know that “him” matches “Man”, so maybe we should leave it as is. 
Still, it jarred me.  I would say “via the attacker.”

— Section 3.1.1 —
I love the ASCII-art stick figures.  :-)

   just for tracking people or as a preliminary to targeted attacks.

“preliminary” isn’t a noun.  Maybe “preliminary step”, or maybe “preamble”?  Or
you could remove “as a”, and it would work.  Yes, I think the last is the best
fix here.

— Section 3.1.2 —

   such as
   for example an airport's lounge.

Nit: “for example” needs to be set off with commas before and after it.

— Section 3.1.3 —

   to further attacks, from theft to device specific hacking.

Nit: hyphenate “device-specific”.

   "fingerprint" of the person, allowing identification.

Style: I would say “facilitating identification”, or maybe “risking
identification”.

— Section 3.2 —

   This is mainly relevant for unicast based discovery

Nit: hyphenate “unicast-based”.

— Section 3.2.4 —

   o  Some attributes like the paper size available in a printer,

Fruit flies like a banana?  The attributes are not paticularly fond of
anything: “Some attributes, such as the paper size available in a printer,”

   Combinations of attributes have more information power than specific
   attributes

Style: I would say, “than individual attributes”

   Information contained in TXT records does not only breach privacy

Nit: make it “…records not only breaches privacy”

   Further, TXT records often contain version information about services
   allowing potential attackers

You need a comma after “services” — otherwise, the meaning isn’t quite as you
want it.

— Section 3.2.5 —

   An argument is sometimes made that devices providing services can be
   identified by observing the local traffic, and that trying to hide
   the presence of the service is futile.  However,

Given what you say below this, I think it would help to emphasize the point
here, so may I suggest this?:

NEW
   An argument is sometimes made that devices providing services can be
   identified by observing the local traffic, and that trying to hide
   the presence of the service is futile.  However, there are good
   reasons for the doscovery service layer to avoid unnecessary exposure:
END

— Section 3.2.6 —

   services, such as for example some private messaging services.

“such as” already means “for example”, so you don’t need both.  I would just
remove “for example”.

— Section 3.4.1 —

   can perform, the proxy may have some way to wake the device, as
   implied in RFC6762 [RFC6762]

6762 is 50 pages-ish; do you mind adding a section to the citation to help the
reader find the implication?

— Section 3.4.2 —

   Further it may cause an unnecessary level
   of power consumption which is particularly problematic

Nit: this needs a comma after “further” and another after “consumption”.

   unauthorized observers, while also managing to do that efficiently.

You’re missing an antecedent to “that”.  I think you need to say, “to do its
job efficiently,” or something like that.

— Section 3.4.3 —

   establishment requires active participation of the user, such as
   entering a password or PIN.

I submit that “clicking OK” is also active participation.  Maybe “more
significant participation” is better?

— Section 4 —

   lead to a solution that does not transmit privacy violating DNS-SD

Nit: hyphenate “privacy-violating”.

   mechanisms should be used on deeper layer network protocols and on
   how to actually connect to services in a privacy preserving way,

Nit: hyphenate “deeper-layer” and “privacy-preserving”.

— Section 4.2 —

   4.  Avoid disclosure of information about the services they offer to
       unauthorized clients.

This sounds like it’s talking about services that they offer to unauthorized
clients.  I don’t actually think readers will misunderstand it, but they might
trip over it.  Maybe move “to unauthorized clients” after “disclosure”?  That
way, you can make the same change in bullet 3 and keep them parallel and clear.

— Section 4.3 —

       Further, it would
       increase power consumption which is critical for IoT devices.

Increased power consumption isn’t what’s critical; just the opposite.  Maybe
“which is damaging to IoT devices.”

— Section 7 —
Do with this comment what you will: I’m one who believes that Informational
documents do have Normative References.  Those are the references that are
critical to the understanding of the document.  Clearly, the DNSSD and mDNS
documents are in that category, and I think there are others.  You needn’t
reply on this, and you needn’t do it if you disagree, but I think it would be
best to identify the key documents that readers of this need to be familiar
with, and move them into Normative References.

---

From: Christian Huitema <[email-masked]>
Date: Tue, 25 Feb 2020 20:42:39 -0800

Thanks for the review, Barry. We will address your comments in the next
revision of the draft.

I am not enthusiastic about "normative references in informational
documents". I will wait for Eric's advice on that one, assuming that he
will carry the IESG consensus on that topic.

-- Christian Huitema

---

From: Barry Leiba <[email-masked]>
Date: Wed, 26 Feb 2020 08:48:46 -0800

Thanks, Christian, and I appreciate your quick response.

> will carry the IESG consensus on that topic.

Éric and I will discuss it.  Meanwhile, I'll note that the IESG said
this in 2006: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/

"Normative references specify documents that must be read to
understand or implement the technology in the new RFC, or whose
technology must be present for the technology in the new RFC to work."

and

"Note 3: The normative/informative distinction is relevant in any
document that amounts to a technical specification, even if its
intended status is Experimental or Informational."

Barry

---

From: "Eric Vyncke (evyncke)" <[email-masked]>
Date: Thu, 27 Feb 2020 17:04:55 +0000

Christian, Daniel,

Based on the IESG statement below, please update the document (after the telechat) to include those references as normative.

Thank you

-éric

-----Original Message-----
From: iesg <[email-masked]> on behalf of Barry Leiba <[email-masked]>
Date: Wednesday, 26 February 2020 at 17:49
To: Christian Huitema <[email-masked]>
Cc: David Schinazi <[email-masked]>, "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>, The IESG <[email-masked]>, "[email-masked]" <[email-masked]>
Subject: Re: [dnssd] Barry Leiba's Yes on draft-ietf-dnssd-prireq-05: (with COMMENT)

    

    and

    Barry