[OPSEC] Opsdir last call review of draft-ietf-opsec-v6-21

Tim Chown via Datatracker <noreply@ietf.org> Fri, 06 December 2019 09:34 UTC

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Date: Fri, 06 Dec 2019 01:34:30 -0800
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Subject: [OPSEC] Opsdir last call review of draft-ietf-opsec-v6-21
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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
threats.

I had previously reviewed the draft as an OPS-DIR Early Review in July 2018, as
detailed in
https://mailarchive.ietf.org/arch/msg/opsec/6s_YFrXNPwtbQRe62D3_AtXb6as, 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
read.

Specific comments:

Abstract:

“places” should be “aspects” or similar.

2.1.1:

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

2.1.5:

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
addresses.

2.1.6

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.

2.2.4

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

2.3.3

“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.

2.6.1.5

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.

2.7.1

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

3.2

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.

4.3

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
reason.