Re: 64bit MAC addresses and SLAAC

On Thu, 18 Jun 2020 at 20:14, Philip Homburg
<pch-ipv6-ietf-6@u-1.phicoh.com> wrote:
>
> >> If a host is connected to a subnet that has multiple prefixes, then using
> >> the same IID for all prefixes only has marginally less privacy than
> >> using different IIDs.
> >
> >Well, it does allow correlation of network activities across addresses.
> >In a way, that's kind of the same as when a host moves across networks.
>
> My home network has a number of prefixes. From reverse DNS you can easily
> figure out that they are the same. How does it help me to have different IIDs
> for different prefixes?
>
> Same applies to any org that tries to renumber.
>
> I'm not saying that anything needs to be changed. Just that we should not
> oversell the privacy benefits.
>

I don't think we are. However, we also don't want to fall into the
trap of "it's not perfect, so let's do nothing". We're limited to
within our problem space, however we should try to provide the best
privacy we can without impacting end-user experience, or at least
limit impacting end-user experience to only when it is necessary to
try to assure privacy.

Similar to security, I think privacy is a weakest link problem. We
don't want IPv6 addresses to be the weakest link within the set of
device, OS or application session identifiers that reduce a device's
end-user's privacy.

For end-user devices, IPv6 addresses with privacy properties by
default is the best choice because typical end-users are not going to
have any idea what an IPv6 address is, let alone be able to properly
evaluate the privacy implications of whether or not they should have
IPv6 privacy addresses.

Regards,
Mark.

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