Hi Chris,

This is difficult to answer without the configurations for Kea and the
Debian interface configuration (/etc/network/interfaces) as well as
the Kea logs (or even better, a pcap file showing the client/server
dhcp packets obtained with: `tcpdump -i <interface> -w <pcapfile.pcap>
port 67` while the client is obtaining two addresses).

Thank you,
Darren Ankney

On Tue, Jan 20, 2026 at 11:58 AM Sonic <[email protected]> wrote:
>
> Installed a new VM of Debian Trixie (using systemd-networkd, which is
> not the default) and set up a reservation (mac address) in Kea and
> noticed that two IPv4 addresses were assigned. The reserved address of
> a.b.c.92 and one from the dynamic pool a.b.c.240.
> I haven't seen this issue with any other VM or bare metal systems -
> various Linux, OpenBSD, and Windows systems.
> Sadly the version of Kea that I'm using is old - 2.4.2, as it is the
> latest available on OpenBSD.
> It appears that one address is being assigned due to the mac address
> (reservation) and a second due to the duid.
> I have:
> ================
> "host-reservation-identifiers": [ "hw-address" ],
> ================
> in the Kea config which supposedly stops reservations based on other
> identifiers (duid, etc.), but apparently does not affect the dynamic
> pool.
> I can mitigate this issue in Debian by adding:
> ================
> [DHCPv4]
> ClientIdentifier=mac
> ================
> to the specific network config file. Although changing the default via
> the networkd.conf file or a specific override via a new file in the
> networkd.conf.d directory does not work (I suspect these are Debian
> bugs).
> Is this a bug in Kea-2.4.2 that it continues to add addresses even
> when a reservation exists, or something lacking in my configuration?
> Thank you,
> Chris
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