[Kea-users] dhcp6 address assignment

[Dan Oachs]

I have recently learned that it is normal and expected that the DUID may
contain the MAC address of a different network device.  For example, an
Apple laptop ( that has only wifi ) will generate its DUID the first time
it boots and use that DUID for everything.  Wifi, usb-ethernet dongle, etc.

Windows has its own way of generating a DUID.  And on Linux, most distro's
will use a DUID but you can change a config file to have it use a link
local address instead.

While this info does not directly solve your problems, hopefully it helps
you understand how things are working.

The short answer is that you might need to rethink the way you use DHCP
(v6) on your network.  I know I have been struggling with some of the
differences making it difficult or impossible to do things the way we had
in the past.  For example, we can no longer assume a usb to ethernet
adapter will have a specific IPv6 address assigned to it, the address might
change depending on what host it is connected to :(


Thanks,
  Dan Oachs



On Tue, Oct 18, 2022 at 1:15 PM Marek Greško via Kea-users <
kea-users at lists.isc.org> wrote:

> Hello,
>
> I am in a phase of migration ISC DHCPD into kea and I am suffering several
> problems in ipv6 address assignment.
>
>
>    1. I used to assign same ipv6 address for the same machine which was
>    dial boot linux/windows. It was possible by assigning same ipv6 address to
>    both DUIDs before. But in kea this is not allowed. I found out there is a
>    possibility to assign ipv6 address by MAC address which was not possible in
>    ISC DHCPD. I was very happy with that finding but fallen into second
>    problem.
>    2. The windows machine got 2 interfaces ethernet and wifi. I
>    configured kea to assign one ipv6 address to the ethernet adapter and
>    another one to the wifi adapter. But after investigating logs kea was
>    receiving dhcp6 request over wifi using the ethernet adapter mac address.
>    How is this possible? Is it possible the MAC address in DHCP does not match
>    L2 MAC address? I did not sniff the request, yet. I decided to switch back
>    to DUID assignment since this problem is worse than the previous.
>    3. Maybe it would be possible to overcome the above problems if kea is
>    able to match both DUID and MAC address, but it is not allowed in kea. I am
>    ought to select one option only. Why?
>
>
> Thanks
>
> Marek
>
>
> Thanks
>
> Marek
>
>
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