[Kea-users] Dynamnic option generation (boot-file-name)

[Darren Ankney]

Hi,

You could create a reservation for each client and set the
"boot-file-name" to the desired parameter.  This reservation need not
contain anything but the mac address and the boot-file-name parameter.
These can be added with the API.  If this is not attractive, I suggest
that you create an account in Gitlab and open a new issue here:
https://gitlab.isc.org/isc-projects/kea/-/issues as I did not see any
preexisting issue there requesting this feature.

Thank you,
Darren Ankney

On Mon, Oct 27, 2025 at 7:02 AM Marcin Jurczuk <spock at omegastar.eu> wrote:
>
> Hi Guys,
>
> I'm fighting for past few days with kea setup for migration from ISC-DHCP.
> I can't make file option in DHCP packet set to dynamic value:
> My device expects  next-server and filename value provided by dhcp and filename config path must be autogenerated and based on device MAC
> I was able to set up option 67 with this:
>      {
>         "library": "/usr/lib/kea/hooks/libdhcp_flex_option.so",
>         "parameters": {
>           "options": [
>             {
>               "add": "concat(hexstring(pkt4.mac,''), '.cfg')",
>               "client-class": "STB",
>               "code": 67
>             }
>           ]
>         }
>       }
>
> This works as expected in terms option generation but device don't want option 67 - it wants boot-file in DHCP (bootp) packet
>
> That seems very populat stuff in DOCSIS/PON world where boot-file is either MAC/Serial/other dynamic string so there must be easy way to set this up :)
>
> However all my attempts to make it for filename field failed.
> Any idea how to achieve this without writing own hook ?
>
> Thanks in advance.
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