issues with ipv6 and DUID

Steven Carr sjcarr at gmail.com
Fri Apr 5 17:43:13 UTC 2013


DUID-LLT is not meant to be dynamic in the sense of constantly regenerating
itself, it's dynamic in that it creates a new DUID once based on a known
hardware ID + timestamp + link local ID to hopefully generate a DUID that
is unique (hardware ID and link local ID can be manually changed in most
OSs so you can't rely on them being unique).

And it defaults to DUID-LLT as that is what is required in the RFC:*
DUID-LL is recommended for devices that have a permanently-connected
network interface with a link-layer address, and do not have nonvolatile,
writable stable storage.  DUID-LL MUST NOT be used by DHCP clients or
servers that cannot tell whether or not a network interface is permanently
attached to the device on which the DHCP client is running.*

You need to find out why dhclient keeps regenerating the DUID-LLT value,
find out where dhclient stores that value and then monitor the file for
changes to see what/why it is being changed.



On 5 April 2013 18:22, Cory Coager <ccoager at gmail.com> wrote:

> On Fri, Apr 5, 2013 at 10:42 AM, Steven Carr <sjcarr at gmail.com> wrote:
>
>> So if it doesn't support the -D flag then what else doesn't it support.
>> When it comes to IPv6 you really need to be on the bleeding edge as the
>> code to support it is still rapidly changing having features/bug fixed.
>>
>
> I read somewhere online that this flag was added in 4.1.1 where I am using 4.1.ESV-R4-0ubuntu5.6
> on Ubuntu 12.04.  I'm guessing this is an older version then.  I wonder if
> there are any other options available without having to upgrade?  Why does
> it default to LLT?  Is there a way to override this besides this flag?
>
>
>>
>> As for the DUID-LLT always changing, that is wrong, RFC3315 states:
>> *Clients and servers using this type of DUID MUST store the DUID-LLT in
>> stable storage, and MUST continue to use this DUID-LLT even if the network
>> interface used to generate the DUID-LLT is removed.  Clients and servers
>> that do not have any stable storage MUST NOT use this type of DUID.
>> *
>>
>
> I agree, the description is misleading.  If DUID-LLT is meant to be
> dynamic, who cares if it changes all the time?
>
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