[Kea-users] Missing features from dhcp-eval

[Vladimir Nikolic]

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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