Question re session hijacking in dual stack environments w/MacOS

Owen DeLong owen at
Fri Oct 16 18:50:52 UTC 2015

> On Oct 2, 2015, at 00:46 , Valdis.Kletnieks at wrote:
> On Fri, 02 Oct 2015 00:46:47 -0500, Doug McIntyre said:
>> I suspect this is OSX implementing IPv6 Privacy Extensions. Where OSX
>> generates a new random IPv6 address, applies it to the interface, and then
>> drops the old IPv6 addresses as they stale out. Sessions in use or not.
> Isn't the OS supposed to wait for the last user of the old address to close
> their socket before dropping it?

No… It just waits for the valid lifetime to expire.

Privacy addresses don’t refresh their preferred lifetime and start counting the valid lifetime from preferred expiration IIRC.


More information about the NANOG mailing list