Re: [v6ops] A common problem with SLAAC in "renumbering" scenarios

[Tom Herbert <[e-mail]>]

On Thu, Feb 21, 2019 at 5:04 PM Owen DeLong <[e-mail]> wrote:
>
>
>
> > On Feb 21, 2019, at 16:18 , Tom Herbert <[e-mail]> wrote:
> >
> > On Thu, Feb 21, 2019 at 3:49 PM Owen DeLong <[e-mail]> wrote:
> >>
> >>
> >> Mark,
> >>
> >> I agreee with that with one exception. I believe that NAT/IPv4 can
> >> offer better privacy in addressing than IPv6 given current addess
> >> allocation methods.
> >>
> >>
> >> Huh? Random 64 bit numbers are less private than semi-opaque translation of 32 bit numbers?
> >>
> >> In today’s world (where CGN is fortunately still mostly the exception rather than the rule), the
> >> 32 bit public number (mostly) identifies the household on a transient basis.
> >>
> > Owen,
> >
> > Privacy in CGN effectively if the device lives behind a NAT with
> > thousands of user. So if the an external external third party observes
> > two different flows that share the same NAT address, then the observer
> > can not infer that the two flows are sourced form the same device or
> > user.
> >
>
> Sure, but today, CGN is the exception, not the rule… Hopefully it will remain that way for the
> foreseeable future as CGN is really an awful awful thing for the end user.
>
> Also, due to CALEA constraints, most CGN implementations are going to quasi-static port
> reservations per household, so it’s not as private as you think it is. It will raise the bar
> slightly, forcing the third party to track an extra 32 bits per flow (2xport number), but that’s
> about it.
>
Owen,

To be clear, I was not advocating NAT. I was only pointing out that it
has some privacy properties to the extent that even law enforcement
has even expressed concerns about it. For those users for which
privacy is vital, I don't believe it's an adequate solution. If
privacy is essential then I believe we really want single use
untrackable addresses  (see
draft-herbert-ipv6-prefix-address-privacy-00).

Tom

>
> Owen
>