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Re: Linux kernel handling of IPv6 temporary addresses
From: George Kargiotakis <kargig () void gr>
Date: Thu, 17 Jan 2013 14:27:25 +0200

Hello, 

On Thu, 17 Jan 2013 17:21:33 +0530 (IST)
P J P <ppandit () redhat com> wrote:

+-- On Wed, 16 Jan 2013, George Kargiotakis wrote --+
|        valid_lft 131007sec preferred_lft 65471sec
|  inet6 fd00:966b:7196:c731:222:aaff:fecc:1111/64 scope global
tentative dynamic |        valid_lft 131007sec preferred_lft 65471sec
| 
| what I also find wrong here is that all temporary addresses
(dynamic) | acquired have gotten the same last 64bits. I don't think
this is OK per RFC | 4941 even if not explicitly defined there. Every
temp. address created | should be different per prefix from the rest.

   True, the last few bits of the addresses are same as the IPv6
address of the host, with scope::global, but no tentative dynamic
bits set. Plus network becomes unreachable till I reboot the host.

| use_tempaddr for the iface still has '2' as its value
| # cat /proc/sys/net/ipv6/conf/eth0/use_tempaddr 
| 2

   This value is always 0, before ifconfig eth0 down and after
ifconfig eth0 up.

Ubuntu is the only distribution that has by default enabled Privacy
Extensions as far as I know. On your RHEL it's '0' and
that's why you weren't seeing any 'ipv6_create_tempaddr' as previously
mentioned on your emails. If you change this value to '2' you'll also
see those kernel messages.


Thank you.
--
Prasad J Pandit / Red Hat Security Response Team
DB7A 84C5 D3F9 7CD1 B5EB  C939 D048 7860 3655 602B


Regards,
-- 
George Kargiotakis
https://void.gr
GPG KeyID: 0xE4F4FFE6
GPG Fingerprint: 9EB8 31BE C618 07CE 1B51 818D 4A0A 1BC8 E4F4 FFE6


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