Re: 6man w.g. last call for <draft-ietf-6man-default-iids-11.txt>

[Alexandre Petrescu <[e-mail]>]

Le 19/05/2016 à 01:22, 神明達哉 a écrit :
> At Tue, 17 May 2016 22:13:36 -0400, Fernando Gont
> <[e-mail]> wrote:
>
>>> From this one, and your response to the next point, it seems you
>>>  are saying the decision was to refuse to address that concern.
>>> Am I understanding it correctly?
>>
>> No. My take is that the concern is flawed. Please read
>> draft-gont-predictable-protocol-ids, and even RFC4941, which talks
>>  at length about security and privacy issues regarding reusing
>> identifiers in different context, for different scopes, etc.
>>
>> Let's call a lemon a lemon: Asking to embed a layer-2
>> identifier/address in a layer-3 address is extremely bad.
>
> I don't have a strong position on this matter itself, but my
> understanding of the sense of the wg is that this is controversial,
> and at least far from a clear consensus.  To repeat myself, *my*
> concern on this last call is that it's not even clear, at least to
> me, if this draft tries to say embedding a link-layer address is,
> whether it's randomized or not, "extremely bad" (and must therefore
> be prohibited).

This explanation makes me think of the following.

A true link-layer address, or a randomized link-layer address, embedded
(or not) in an Interface ID - is a matter of Ethernet only.  That could
lead to update "IPv6 over Ethernet" RFC 2464, and not create a new RFC
default-iids.

Moreover, it may be that people on cable Ethernet in Enterprise have
less privacy concern.  It's people on WiFi who do because they're more
mobile and no subject to internal codes of conduct.  And, unfortunately,
there is no "IPv6 over WiFi" RFC to update with this true link-layer vs
randomized link-layer address.  First, one should write an "IPv6 over
802.11" RFC.  Then we can talk about link-layer vs randomized in IID for
WiFi.

Second, this (true link-layer or radomized link-layer address in IID)
is not relevant for other link layers such as USB, or cellular wireless
access links, or others.  There is no worry here about 'true' vs
'random' link-layer address in the first place (whether in IID or not),
because there is no 'true' (i.e. IEEE-assisgned) link-layer address.  In
addition, on cellular links the prefix advertised in RA is unique per
terminal - so _that_ could be a privacy issue (not the IID).

Before privacy concerns, there is an issue to make IPv6 does run on
these links: people struggle to create 48bit addresses which can fill
the structures needed in IPv6 programming.  These addresses may look
random, but are actually based on hints, thus creating something
predictable.  The issue here is that is not standardized and may lead to
conflicts.  _After_ that conflict issue is solved, can we talk about
IID privacy issues of true-vs-random link-layer address in these links.

Alex