I’m not a fan of IPv6 privacy addressing. I understand the logic behind it, I really doo, obfuscate the LLADDR (MAC address) of the host in question, but I really dont’t see the realistic purpose. If someone wanted to use my mac address, what good would that really get them, unless they’re on the same layer 2 segment? More importantly, if they;re on the same layer 2 segment, they have my MAC address anyway.
Privacy addresses cause more heartburn than they cure. How do I track someone who has a rotating address? Am I scraping the neighbor table of my network equipment often enough to have reasonable accountability? Probably, but what if I’m not? I could go on and on about how I think RFC4941 addresses aren’t that useful, but instead I’ll just write down how to disable them (I’ve always been known as more of a machete than a scalpel anyway =).

With MacOS 10.7 (Lion) it’s now on by default. To disable it, you need to open a terminal and type:

_sudo sysctl -w net.inet6.ip6.use_tempaddr=0
_
Poof! There you go. You should be using DHCPv6 anyway =) [](http://events.internet2.edu/2011/jt-uaf/agenda.cfm?go=session&id=10001852&event=1151) *cue vendors getting off their rear ends and implementing dhcpv6 relay*

-–edit—

A good point made by Charley Kline, to make this persist across reboots a line needs to be added to your /etc/sysctl.conf.

To accomplish this, edit /etc/sysctl.conf

sudo vi /etc/sysctl.conf

Add the following line:

net.inet6.ip6.use_tempaddr=0

--edit–

For all you windows users:

XP:

netsh interface ipv6 set privacy state=disabled store=persistent
netsh interface ipv6 set privacy state=disabled

Vista:

netsh interface ipv6 set global randomizeidentifiers=disabled
netsh interface ipv6 set global randomizeidentifiers=disabled store=persistent
netsh interface ipv6 set privacy disabled

I assume Windows 7 is similar to Vista, but I have not tested.

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