On Wednesday, December 17, 2025 12:04:01 PM Central European Standard Time
Carsten Strotmann via Kea-users wrote:
> 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-d
> dns-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
Thank you very much for your answer.
I've just tested this solution. Option 12 works like a charm.
Sadly the ddns entries aren't written i.e. they don't end up in the bind9
zones.
My configuration:
"Dhcp4": {
"hooks-libraries": [
{ "library": "libdhcp_flex_option.so",
"parameters": {
"options": [
{
"name": "host-name",
"supersede":
"concat('vm-',hexstring(option[50].hex,''))",
"csv-format": true
}
]
}
}
],
"hw-address": "<hw-address>",
"ip-address": "<ip-address>",
"hostname": "<hostname>"
are written correctly in bind9.
Would it be possible to limit the libdhcp_flex_option.so hook to a specific
pool
or interface.
Regards,
Joop Boonen.
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