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

[Lorenzo Colitti <[e-mail]>]

On Thu, May 19, 2016 at 2:19 PM, Alissa Cooper <[e-mail]> wrote:

> The draft makes just about a clear a statement in this vein as is possible:
>
> "By default, nodes SHOULD NOT employ IPv6 address generation schemes
>    that embed the underlying link-layer address in the IID.”
>
> Note that this statement does not prohibit anything, nor does it make a
> normative (in the moral sense) judgment. It just states the recommendation,
> which is the point of the document.
>
> I appreciate that not everyone on the list agrees with this
> recommendation. But I find the claim that this recommendation is unclear to
> be difficult to understand. That is, I can’t think of a way to convey the
> same recommendation that would be clearer. If you can, please suggest text.
>

Alissa,

I don't think anybody is claiming that the recommendation itself is
difficult to understand. What is difficult to understand is how the
document justifies that claim.

It looks like the main argument used to justify this recommendation is
major privacy risks. But embedding a link layer identifier into an IP
address is not a major [1] privacy risk. It is only embedding a *STABLE*
link-layer address that is a major privacy risk.

Recommending that link-layer address be embedded only if they are ephemeral
would address the privacy concerns just as well as (or maybe even better)
than the approach proposed in this document.

I think what people are do not understand is why this document recommends
one but not the other. I certainly don't.

Cheers,
Lorenzo

[1] I argue that cross-referencing IPX traffic to IP traffic is not a major
privacy risk because IPX is so uncommon.