[Kea-users] dynamic hostname Option 12 in a kea pool

[Carsten Strotmann]

Hi Joop,

On 17 Dec 2025, at 11:29, Joop Boonen wrote:

> Dear all,
>
> I didn't find any option to implement dynamic host-names in kea pool.
>
> Like this in isc dhcpd.
>
> subnet 172.26.250.0 netmask 255.255.254.0 {
>   set machex = binary-to-ascii(16, 8, "", substring(hardware, 1, 6));
>   set macsuffix = suffix(machex, 6);
>   set hstnm = concat("vm-", macsuffix);
>   option host-name = hstnm; # Option 12
> -->8--
>
> i.e.
>
>   pool {
>     range 172.26.250.64 172.26.251.250;
>    set machex = binary-to-ascii(16, 8, "", substring(hardware, 1, 6));
>    set macsuffix = suffix(machex, 6);
>    set hstnm = concat("vm-", macsuffix);
>    option host-name = hstnm; # Option 12
> -->8--
>
> Does anyone know if this is possible, in kea?
>

Yes, it is possible, even via multiple ways:

1)
via DDNS-Tuning, see the examples at
https://kea.readthedocs.io/en/stable/arm/hooks.html#libdhcp-ddns-tuning-so-ddns-tuning

2)
via flexible-options (the expression below is build based on your ISC-DHCP code, I've not tested it):

      {
        "library": "libdhcp_flex_option.so",
        "parameters": {
            "options": [
                {
                   "name": "host-name",
                   "supersede": "concat("vm-",substring(hexstring(option[host-name].hex,""),-1,6))",
                   "csv-format": true
                },
          ]
        }
      },

Greetings

Carsten