macos Sierra with CGA address?

Fernando Gont fernando at
Wed Dec 14 23:38:51 CET 2016

On 12/14/2016 08:25 AM, Holger Zuleger wrote:
>>> Has anyone more information about this? Especially how to configure it?
>> The only trick I found out was:
>> 8<-------
>> Also who has typed: "sudo sysctl -w net.inet6.ip6.maxifprefixes=1" (or
>> stored the setting in /etc/sysctl.conf) recently? ;)
>> --------->8
> To be honest, that's definitively is not the way I like to go.
>> As then you only get the DHCPd address (requires DHCPv6 server....) on
>> your interface and not all the other magic ones that change all the time
>> and are extremely useless if you want to ADDRESS a host...
>> (yes, I love VNC'ing, SSH'ing and doing SSH-backups of my boxes...)
> Oh no, DHCPv6 is not needed here.
> The problem is *not* that this IID is changing. It is a stable one. And
> yes, I vote not against temporary addresses.
>> There are claimed 'good' properties of a changing address but mostly
>> they are useless: "it works against tracking" which is useless if your
>> /48 is static and there are only ~10 hosts in that prefix that call
>> outbound. Also, something with HTTP Cookies for 99% of the other things.
>> And I am really not lugging my 27" iMac around to get it in another
>> network....
>> Hence, a switch to turn if off.... would be amazing.
>> The above trick kinda does that though and it mostly seem to work.
> My info is, to set
> 	sysctl -w net.inet6.send.opstate=0
> to go back to mac address based eui64, but didn't checked it.

Please don't resort to eui64. That's a bad idea. See RFC7721 and RFC707

Fernando Gont
e-mail: fernando at || fgont at
PGP Fingerprint: 7809 84F5 322E 45C7 F1C9 3945 96EE A9EF D076 FFF1

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