SV: Windows 7 and SLAAC?

Bøvre Jon Harald Jon.Harald.Bovre at
Tue Mar 30 13:47:00 CEST 2010

Copy/paste from this page:
(check section 'Latest Post')

You are right. Windows 7 (Server 2008 & Vista as well) by default randomizes ipv6 auto-configured address selection. This is in violation with section 4 of RFC 2464 that mandates that the network identifier part of the IPv6 address is derived from the 48-bit MAC address for Ethernet (and Wireless) interfaces.
It may be that Microsoft chose to do this for privacy reasons..

For most users this will not be much of a problem but for those running a server it will. There is however a solution:

netsh interface ipv6 set global randomizeidentifiers=disabled

This will switch the feature off and address selection will be based upon the EUI-64 identifier, derived from the interface’s built-in 48-bit IEEE 802 address.


Fra: at [ at] på vegne av Gert Doering [gert at]
Sendt: 30. mars 2010 13:42
Til: Tore Anderson
Kopi: Gert Doering; ipv6-ops at
Emne: Re: Windows 7 and SLAAC?


On Tue, Mar 30, 2010 at 01:34:22PM +0200, Tore Anderson wrote:
> > Does one of you have a pointer for me what Windows 7 is using here?  Some
> > sort of "windows installation global identifier"?
> I believe this is due to Windows 7 is using privacy extensions with
> SLAAC by default (RFC 4941).

No, that's something else.  I see two (global) IPv6 addresses on the
link, one that keeps changing (privacy) and one that is static - but
neither is related in any way to the card's MAC address.

Gert Doering
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