Windows 7 and SLAAC?

David Horn dhorn2000 at gmail.com
Tue Mar 30 21:23:38 CEST 2010


On Tue, Mar 30, 2010 at 2:55 PM, Gert Doering <gert at space.net> wrote:

> Hi,
>
> On Tue, Mar 30, 2010 at 01:04:57PM -0400, Marshall Eubanks wrote:
> > >> Microsoft has a "Cable Guy" article that describes Vista/Win 7
> > >> autoconf behavior, including the netsh CLI interface syntax for this
> > >> particular setting.
> > >>
> > >> netsh interface ipv6 set global randomize identifiers=disabled
> > >>
> > >> http://technet.microsoft.com/en-us/magazine/2007.08.cableguy.aspx
> > >> for
> > >> more information.
> >
> > I would assume that these are not constant.
> >
> > RFCs 4941 describes "privacy extensions" that yield changing (pseudo)
> > random interface IDs and RFC 5157 provides a background into why this
> > is could be a good thing.
>
> Different thing.  Win7 has 4941 IPv6 addresses *and* not-directly-MAC-
> related IPv6 addresses.
>
>
Based upon my own Win7 observations, the default random IID is at least
somewhat permanent (In that it survives across reboots), and that it is
stored somewhere (as the random IID is the same even after disabling and
re-enabling randomization via netsh)

Based upon a document from MS:
http://download.microsoft.com/download/e/9/b/e9bd20d3-cc8d-4162-aa60-3aa3abc2b2e9/ipv6.doc

I think the default Vista/Win7 IID is a "permanant" randomized identifier.
See snippet below:

    - It is a permanent interface identifier that is randomly generated to
mitigate address scans of unicast IPv6 addresses on a subnet. This is the
default behavior for IPv6 in Windows Vista and Windows Server 2008. You can
disable this behavior with the netsh interface ipv6 set global
randomizeidentifiers=disabled command.�

Good Luck.

-_Dave Horn
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