[Kea-users] dhcp6 and ntp-server, version 3.0.3

[Darren Ankney]

Hi again Charly,

Just looked at the title more closely and saw that you were asking
about dhcp6.  Same two files may be of interest (different directory):

- https://gitlab.isc.org/isc-projects/kea/-/blob/master/doc/examples/kea6/all-keys.json
- https://gitlab.isc.org/isc-projects/kea/-/blob/master/doc/examples/kea6/all-options.json

Option 56 (ntp-server) isn't shown there.  It is a bit more
complicated as it has three possible types of sub-options (see
https://datatracker.ietf.org/doc/html/rfc5908) which are Server
Address Suboption (can only contain one IP), NTP Multicast Address
Suboption (may contain one multicast group address),  and NTP Server
FQDN Suboption (may contain one FQDN).  In which one were you
interested?  The option can only convey one sub-option.  According to
the RFC, each sub-option can only contain one value, and the ARM
(https://kea.readthedocs.io/en/kea-3.0.3/arm/dhcp6-srv.html#ntp-server-suboptions)
says that only one sub-option can be included: "Each option instance
carries one and only one suboption as required by RFC 5908.".
However, this seems to be at odds with the option format shown in the
RFC: https://datatracker.ietf.org/doc/html/rfc5908#section-4 which
shows multiple sub-options.

Can you share what you have tried already?

Thank you,
Darren Ankney

On Fri, May 1, 2026 at 5:13 AM Darren Ankney <darren.ankney at gmail.com> wrote:
>
> Hi Charly,
>
> You can find an example of how to configure time-servers here:
> https://gitlab.isc.org/isc-projects/kea/-/blob/master/doc/examples/kea4/all-options.json?ref_type=heads#L47-58
>
> In fact there are two files there in which you may be interested:
> - https://gitlab.isc.org/isc-projects/kea/-/blob/master/doc/examples/kea4/all-keys.json
> - https://gitlab.isc.org/isc-projects/kea/-/blob/master/doc/examples/kea4/all-options.json
>
> Perhaps others in that directory may interest you as well.
>
> Have a great weekend!
>
> Thank you,
> Darren Ankney
>
> On Sat, Apr 18, 2026 at 2:16 AM Karl Gaissmaier
> <karl.gaissmaier at uni-ulm.de> wrote:
> >
> > Hello everyone,
> >
> > I'm still pretty new to KEA-DHCP.
> > I've set up a test environment and read a lot on ARM and elsewhere, and
> > everything is going according to plan.
> >
> > However, I can't seem to get more than one IPv6 address for the NTP
> > server sent to the client.
> >
> > Could someone please post a short code snippet showing how to configure
> > this so it works?
> > It would also be helpful if this basic information were included in the
> > examples in the KEA repository.
> >
> > Thanks in advance,
> >   Charly
> > --
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