Subject: draft-ietf-6man-rfc4291bis-06: RFC4941 and comment on stable addresses

From: Fernando Gont <[email-masked]>
Date: Sat, 21 Jan 2017 11:54:25 -0300

Folks,

Just happened to take a look at the I-D and have two comments:

1) The doc says:
"  The details of forming interface identifiers are defined in other
   specifications, such as "Privacy Extensions for Stateless Address
   Autoconfiguration in IPv6" [RFC4941] or "A Method for Generating
   Semantically Opaque Interface Identifiers with IPv6 Stateless Address
   Autoconfiguration (SLAAC)"[RFC7217]. "

While the text is not really incorrect, this one being a bis document to
move rfc4291 to full std, referencing RFC4941 as is has two problems:

  1) It would change the current operating model, where nodes employ
     stable addresses -- in which temp addresses are *additional*
     (to stable addresses) and an optional feature

  2) Referenced "as is", it would seem that RFC4941 is an alternative
     to stable addresses, but as already discussed on this list, RFC4941
     is specified such that temporary addresses are generated in
     addition to the stable ones.

Side comment:

The Security Considerations states:
"  One area relavant to IPv6 addressing is privacy.  IPv6 addresses can
   be created using interface identifiers constructed with unique stable
   tokens.  The addresses created in this manner can be used to track
   the movement of devices across the Internet."

Based on the terminology in RFC7721, it is *constant* tokens (not
stable) that would allow traking across the Internet.

Thanks!

Best regards,
-- 
Fernando Gont
SI6 Networks
e-mail: [email-masked]
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492

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From: Lorenzo Colitti <[email-masked]>
Date: Sun, 22 Jan 2017 20:10:31 +0900

>      (to stable addresses) and an optional feature

That text doesn't change anything. RFC4941 specifies that temporary
addresses are additional to "public" addresses.

>      addition to the stable ones.

The text doesn't imply that at all. It simply says that those are two ways
of generating IIDs, which they are.

---

From: Fernando Gont <[email-masked]>
Date: Mon, 23 Jan 2017 03:28:47 -0300

On 01/22/2017 08:10 AM, Lorenzo Colitti wrote:
> On Sat, Jan 21, 2017 at 11:54 PM, Fernando Gont <[email-masked]
> <mailto:[email-masked]>> wrote:
> 
>     1) The doc says:

This document is a bis document, which is not expected to change
anything, right?

RFC4291 was only about stable addresses. Hence referencing temporary
addresses can be misleading. For instance, RFC4291 does 4291 does not
contain any references to RFC3041.

> The text doesn't imply that at all. It simply says that those are two
> ways of generating IIDs, which they are.

Again, I think that'd be misleading.

Thanks,

---

From: Lorenzo Colitti <[email-masked]>
Date: Mon, 23 Jan 2017 17:10:53 +0900

> This document is a bis document, which is not expected to change

And it doesn't. Whether RFC 4941 is cited in this document or not doesn't
change the normative effects of this document, since it's only provided as
an example.

> contain any references to RFC3041.

RFC 4291 is not just about stable addresses, it's about all addresses
(multicast, unicast, stable, unstable, manual, autoconfigured, random,
...). It says that "all unicast addresses [...][are] constructed in
modified EUI-64 format". That includes RFC 4941 privacy addresses, which
are in modified EUI-64 format (they set bit 6 to 0).