[Kea-users] KEA DHCP4 client classes with mysql

[Darren Ankney]

Hi James,

In theory, there should be nothing special about adding it with the
api command vs. directly in the database.  However, it is possible
that there is something that was missed when you hand added it do the
database.  Perhaps check for differences (maybe with a myslqudmp
before and after) when using the api command to add the host?  The
libdhcp_host_cmds.so hook is now part of the public distribution of
Kea in 3.0.2 so there should be no obstacle to giving this a try.

Thank you,
Darren Ankney


On Mon, Feb 9, 2026 at 6:59 AM James Jalbert via Kea-users
<kea-users at lists.isc.org> wrote:
>
> So I have to add the reservation with the command? I have added it with the mysql commands with the same info
> James Jalbert
> Network Administrator
> Eastern Aroostook RSU #39
> Phone: 207-493-4246 Ext 1275
>
>
>
>
> On Sat, Feb 7, 2026 at 7:32 AM Darren Ankney <darren.ankney at gmail.com> wrote:
>>
>> Hi James,
>>
>> You will need a hosts_database that specifies mysql as shown here:
>> https://kea.readthedocs.io/en/kea-3.0.2/arm/dhcp4-srv.html#dhcpv4-hosts-database-configuration
>> something like this:
>>
>> ```
>>     "hosts-databases": [
>>       {
>>         "name": "kea",
>>         "password": "kea",
>>         "type": "mysql",
>>         "user": "kea"
>>       }
>>     ]
>> ```
>> You will only need to load libdhcp_myslq.so, libdhcp_hosts_cmds.so,
>> for this specific purpose.  For a global host reservation, you need to
>> set "reservations-global": true as described here:
>> https://kea.readthedocs.io/en/kea-3.0.2/arm/dhcp4-srv.html#fine-tuning-dhcpv4-host-reservation
>>
>> To add such a reservation (global) using host_cmds, you need to send
>> the reservation-add API command to Kea using subnet-id 0 as described
>> here: https://kea.readthedocs.io/en/kea-3.0.2/arm/hooks.html#the-reservation-add-command
>>
>> Something like this:
>> ```
>> {
>>     "command": "reservation-add",
>>     "arguments": {
>>         "reservation": {
>>             "subnet-id": 0,
>>             "hw-address": "1a:1b:1c:1d:1e:1f",
>>             "ip-ddress": "192.0.2.1",
>>             "client-classes": [ "classa" ]
>>         }
>>     }
>> }
>> ```
>>
>> After all of that, Kea should be able to find your reservation.
>>
>> Thank you,
>> Darren Ankney
>>
>>
>> On Thu, Feb 5, 2026 at 8:05 AM James Jalbert via Kea-users
>> <kea-users at lists.isc.org> wrote:
>> >
>> > Hello, I hope this is the right list for this.....
>> >
>> > I am setting up the KEA DHCP4 server version 3.0.2 and trying to get client classes to work for my subnets. Here is what I have, and what has worked.
>> >
>> > I set up a global host reservation in the dhcp4.conf file. I set the host reservation with an ip address of one of my subnets and specify client_classes as the class name I want to use(we will say classa). In my subnet lists, I am setting a dynamic pool and telling the server, only give an address from this pool if the class = classa. With the client class set on the reservation, the machine gets an address, exactly what I want.
>> >
>> > Now I am trying to move the host reservation to mysql, as I have thousands of reservations. However, when I put "classa" under the dhcp4_client_classes it is not passed on to the server when the client requests its ip address. I get a message on the server that says failed to allocate address for client with classes ALL, Vendor_Class......., and UNKNOWN
>> >
>> > Why is the class not being sent from the database to the server?
>> > I have loaded the libdhcp_classes_cmds.so, libdhcp_myslq.so, libdhcp_hosts_cmds.so, libdhcp_subnet_cmds.so libraries. Anyone have any thoughts?
>> >
>> > Thanks for any help.
>> > James Jalbert
>> > Network Administrator
>> > Eastern Aroostook RSU #39
>> > Phone: 207-493-4246 Ext 1275
>> >
>> >
>> >
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