Re: Why /64

[Jeroen Massar <[e-mail]>]

On 2013-10-27 20:04, TJ wrote:
>     >>> IMHO big nonsense. The company (amongst many others!) you work for
>     > uses amongst others cookies to track their people,
>     >>
>     >> Not sure we want to get into that argument here, but
>     >
>     > I _don't_ want to get into it here but I want to briefly support
>     Lorenzo
>     > on privacy.  Privacy through controlling tracking of an IP address is
>     > very different in mechanism and result from higher layer end-to-end
>     > privacy.
> 
> 
> First off, ++1 to Lorenzo on all counts (and Scott, Karl).

You can +1 without facts or any backing details, but the fun thing is,
it is no difference at all: privacy addresses do not make you "private"
in any way or form.


The only thing higher levels gives the adversary is a easier detection
and correlation. But unless you have exactly the same packet signature
and you are hitting the same sites as other people in your /64 or /48
you are unique.

Please note that a IPv6 Privacy Address is for a period of time, not per
application (at least I have not seen an OS do that yet, it could, but
they do not).

As such, when your HTTP browser goes to a site, that IP address is
identified as you; then anything else goes to another site, and voila,
they know that that connection is also related to you. Then your privacy
time window expires, you connect to that second site again, which is not
HTTP, but as you have been there just a bit ago, there is a high chance
that that is still you.

>     It does not matter if you have 1 IPv4 address with 2000 people behind
>     it, or 1 /48 with 2000 people behind it.
> 
>     The algorithms to de-anonimize and differentiate between the real hosts
>     behind them exist.
> 
>     Cookies are one way to do that, complete browser profiles or other
>     differences in the client, be that the tcp stack level another. For
>     other protocols it is all much easier as they are typically already
>     authenticated anyway or have other bits.
> 
> 
> 
> Having said that, FWIW - I partially disagree with Jeron here - it does
> matter.

With what exact part do you disagree and what part does matter?


> A user can have browser extensions, multiple browsers (or
> mutliple VMs with different OSes) and have a fairly good level of
> privacy if so desires - as long as the underlying L3 provisioned does
> not prevent it.  Is may not be exactly mainstream / commonplace, but not
> uncommon enough to ignore (IMHO) either.

Even though that would give you separate addresses and would initially
give that user separate identities that are being tracked, that user is
still coming out of the same /64 or /48.

Thus on the IP level indeed it initially looks like multiple users. But
as various organizations are pretty good at estimating amount of users
in a location, they can easily guess that it is the same person anyway.


I'll state again: if you want privacy use a mixnet, eg Tor.
(and even then you are exposing all your random bits, thus beware what
protocols and tools you use)

Greets,
 Jeroen