[Kea-users] Missing features from dhcp-eval

[Vladimir Nikolic]

Thanks Darren.

I'm trying to set up custom next-server and boot-file-name by setting up 
options 66 in 67 through the flex option hook, everything based on 
relaying router ip.
I can see that KEA server sends both these options properly.
But PXE (VMware) client properly picks the filename (option 67) but 
wrongly picks the SIADDR ip instead of TFTP server name (option 66).
I presume flex option hook can't rewrite the next-server (SIADDR) value?

Regards,
Vladimir

On 2023-10-15 21:35, Darren Ankney wrote:
> Hi Vladimir,
> 
> You should be able to do something like this with the flex option
> hook:
> https://kea.readthedocs.io/en/kea-2.4.0/arm/hooks.html#libdhcp-flex-option-so-flexible-option-actions-for-option-value-settings
> 
> Just need to find out what can be tested for.  Is the traffic relayed?
>  Will there be a specific giaddr for the client in the subnet that you
> want to set the custom options?  You can test for a specific relay
> agent IP (giaddr) with pkt4.giaddr == 192.0.2.1, for example.  You can
> test if a client is a member of the PXEClients class with
> member('PXEClients').
> 
> Hope this helps!
> 
> Thank you,
> 
> Darren Ankney
> 
> On Sun, Oct 15, 2023 at 11:40 AM Vladimir Nikolic <vladimir at nikolic.si> 
> wrote:
>> 
>> Let's say I want to send custom next-server and filename to PXE 
>> clients,
>> depending on subnet in which they are located.
>> 
>> In dhcpd, I define a new option, e.g.:
>> option something-new code 250 = string;
>> 
>> Then I set its value in some of the subnets:
>> subnet xyz {
>>      option something-new "my-value";
>> ...
>> 
>> And within a class definition, I can set up options (e.g. next-server
>> and filename) based on the value of something-new option (defined 
>> within
>> subnets):
>> class "PXEClients" {
>>      match if substring(option vendor-class-identifier, 0, 9) =
>> "PXEClient";
>>      if config-option something-new = "my-value"
>>          next-server my-new-server;
>>          filename "my-new-filename";
>>      } else {
>>          next-server my-old-server;
>>          filename "my-old-filename";
>>      }
>> ...
>> 
>> So it's one class with different next-server/filename options, based 
>> on
>> the subnet in which clients live.
>> 
>>  From what I've seen so far, you can't do something similar in KEA.
>> You have to define next-server and filename in every of those subnets,
>> and that will apply to all the clients in that subnet (not just to 
>> those
>> belonging to PXEClients class).
>> 
>> Thanks
>> 
>> 
>> On 2023-10-15 17:18, Darren Ankney wrote:
>> > Hi,
>> >
>> > I'm not entirely sure what you are asking here.  Do you mean that you
>> > need to add a client to a class based on what subnet was selected?
>> >
>> > Thank you,
>> >
>> > Darren Ankney
>> >
>> > On Fri, Oct 13, 2023 at 12:36 PM Vladimir Nikolic via Kea-users
>> > <kea-users at lists.isc.org> wrote:
>> >>
>> >> Hi,
>> >>
>> >> We are struggling with the migration from DHCPD to KEA.
>> >> Is there any easy alternative to this dhcp-eval feature:
>> >>
>> >> config-option option-name
>> >>       The config-option operator returns the value for the specified
>> >> option that the DHCP client or server has been configured to send.
>> >>
>> >> In DHCPD, we define an option, and then set it up on particular
>> >> subnets.
>> >> It can then be used during class evaluation, by config-option feature.
>> >> In that way, different classes (with e.g. different next-server and/or
>> >> filename defined) can be assigned to similar clients, just based on
>> >> the
>> >> option value set in a subnet definition.
>> >>
>> >>  From what we've seen so far, something like that is not possible with
>> >> KEA.
>> >> Looks like we'll have to find an alternative solution.
>> >>
>> >> Thanks
>> >> --
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