Re: [OPSEC] [Last-Call] Opsdir last call review of draft-ietf-opsec-v6-21

Tim Chown <> Fri, 06 December 2019 16:41 UTC

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From: Tim Chown <>
To: Merike Kaeo <>
CC: "Eric Vyncke (evyncke)" <>, "" <>, "" <>, "" <>, "" <>
Thread-Topic: [Last-Call] [OPSEC] Opsdir last call review of draft-ietf-opsec-v6-21
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Date: Fri, 6 Dec 2019 16:41:08 +0000
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Subject: Re: [OPSEC] [Last-Call] Opsdir last call review of draft-ietf-opsec-v6-21
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No problem, it’s not a big issue.  I must admit I didn’t check at the time for any responses after completing the last review.  But now looking back at the opsec archives I don’t see any response to that email (bar a separate comment) nor any changes that I could see to the document as a result.  If there is something I missed please do point it out.

Anyway, if you can consider those comments when looking at the additional notes in the new review, that would be great.  Overall the document is certainly in much better shape than 18 months ago, and very close to being done :)

Best wishes,

On 6 Dec 2019, at 16:17, Merike Kaeo <<>> wrote:

Hi Tim.

You are someone who has over the years made many substantial recommendations to this document so I will echo Eric’s comment that if we did not react to your last review it was a gross oversight.  I will look at my archives since I recall making a concerted effort to make sure we included all the review comments from 2017/2018 in a version around October 2018.

- merike

On Dec 6, 2019, at 6:19 AM, Eric Vyncke (evyncke) <<>> wrote:


Thank you for your additional review. And, I feel really bad if we, the authors, have not reacted to your previous review (even if I had in mind that we acted on it -- possibly not changing the text to fit completely your view)


On 06/12/2019, 10:34, "Tim Chown via Datatracker" <<>> wrote:

  Reviewer: Tim Chown
  Review result: Not Ready

  I have reviewed this document as part of the Operational directorate's ongoing
  effort to review all IETF documents being processed by the IESG.  These
  comments were written with the intent of improving the operational aspects of
  the IETF drafts. Comments that are not addressed in last call may be included
  in AD reviews during the IESG review.  Document editors and WG chairs should
  treat these comments just like any other last call comments.

  This draft analyses operational security issues related to the deployment of
  IPv6, and describes appropriate mechanisms and practices to mitigate potential

  I had previously reviewed the draft as an OPS-DIR Early Review in July 2018, as
  detailed in, but I
  don’t see any evidence of these comments being acted upon, or any response, so
  as far as I can see, the comments in this review still apply, and I would urge
  the authors to review these comments.

  That said, there have been a number of improvements to the draft in the past 18
  months, and overall it is a much better document for those changes.  The
  question is at what point the WG should simply ship the draft as “good enough”,
  rather than try to improve it further.

  At the moment I think the document is Not Ready, though it’s getting nearer to
  being Ready with Nits.

  General comments:

  There are a number of typos / grammatical errors in the document.  While the
  RFC Editor will correct, e.g., in the abstract - “mitigations” should be
  singular, in the intro “with that have been”, in 2.1 “of address space
  available” (add “is”), “allow” should be “allows”.  Just needs a careful proof

  Specific comments:


  “places” should be “aspects” or similar.


  Or for internal communication stability in networks where external connectivity
  may came and go, e.g., many ISPs provide ULAs in home networks.


  This section muddles privacy addresses with stable per-prefix identifiers.
  They have different uses, and can be used independently or together.

  You say “RFC 8064 specifies a way to”, but I think you should cite RFC 7217 as
  the address generation mechanism, and RFC 8064 as the recommendation to use
  that, but note that you can still use RFC 4941 addresses alongside RFC RFC 7217


  As per my previous review I think you should have a section on address
  accountability / auditing, and discuss that for all address assignment methods,
  be it DHCPv6 or SLAAC/RFC7217.  You say here DHCPv6 is used for audit purposes,
  yet later in the doc say there are issues with that approach.

  Address accountability is the most common question I get asked when speaking to
  universities about IPv6 deployment when there is (dual-stack) multi-addressing.

  This can be a place to mention DHCPv6 anonymity profiles, but that would be
  better in a separate section on address and thus user privacy.


  As per later in the document, emphasise here that IPSec is optional (some still
  have the original IPv6 marketing message in their head…)


  “his packets” -> “their packets” to be gender neutral.

  How widely deployed is SAVI in practice?  A comment is rightly made about SeND,
  but what about SAVI implementation?

  Can also suggest the /64 per host isolation approach here before the “A drastic
  technique” paragraph.

  Address accountability appears again here in the 5th paragraph.  You can get a
  level of accountability from polling network devices where DHCPv6 is not used;
  this should be discussed somewhere.


  Should mention RFC 7123 here, and also in Section 3.


  Given you raise VPNs, you should add a note about RFC 7359.

  In R&E campus enterprises, eduroam is widely deployed and gives accountability
  through federated 802.1x based network access.


  You manage to avoid talking about IPv6 NAT until here.  Then assume there is no
  IPv6 NAT on a CPE.  Would it be better to not mention IPv6 NAT at all, or dare
  you open that can of very wriggly worms in this document?  I imagine the IESG
  reviews may ask, given the widely held industry belief that “NAT is added
  security” :).  RFC 4864 still has value, but you cite that for a different

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