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List:       dhcp-users
Subject:    Re: kea-dhcp4 behaviour question client-class vs reservations
From:       Darren Ankney <darren.ankney () gmail ! com>
Date:       2024-04-27 15:35:10
Message-ID: CAKabWHhxz1zrByopsKs6_a-LJS-3fzfgcwW8XWGzF=veJ_1A1w () mail ! gmail ! com
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Hi Philipp,

The keyword "client-class" restricts access to the pool to members of
the class.  It does not assign members of a class to a pool.  See
here: https://kea.readthedocs.io/en/kea-2.4.1/arm/classify.html#configuring-pools-with-class-information
 where it says "Similar to subnets, in certain cases access to certain
address or prefix pools must be restricted to only clients that belong
to a given class, using the client-class when defining the pool.".

Thank you,
Darren Ankney

On Fri, Apr 26, 2024 at 5:05 AM Jan-Philipp Snizek
<jan-philipp.snizek@business.uzh.ch> wrote:
> 
> Hi
> 
> I would like to ask a question regarding precedence behavior of kea-dhcp4.
> 
> Let's take this working config:
> 
> "client-classes": [
> {
> "name": "pxeclientx64",
> "test": "option[60].text == 'PXEClient:Arch:00007:UNDI:003016'",
> "option-data": [
> { "name": "vendor-encapsulated-options", "always-send": false },
> { "name": "boot-file-name", "data": "SMSBoot\\x64\\wdsmgfw.efi" },
> { "name": "tftp-server-name", "code": 66, "data": "my-tftp-server.domain.local" }
> ]
> }
> ],
> "subnet4": [
> {
> "id": 1,
> "subnet": "172.20.19.0/24",
> "next-server": "172.20.19.1",
> "pools": [
> { "pool": "172.20.19.120 - 172.20.19.129" },
> { "pool": "172.20.19.130 - 172.20.19.139", "client-class": "pxeclientx64" }
> ],
> "reservation-mode": "out-of-pool",
> "reservations": [
> { "hostname": "pxeboot1", "hw-address": "00:e0:4c:68:0a:f1", "ip-address": \
> "172.20.19.150" } ],
> "option-data": [
> { "name": "routers", "data": "172.20.19.1" }
> ]
> }
> ],
> 
> If the client with the reservation executes a PXE boot it gets the reserved IP \
> .19.150 and successfully boots PXE. The kea-dhcp4 log looks like this:
> Apr 25 13:53:17 hellbox kea-dhcp4[16858]: INFO  EVAL_RESULT Expression pxeclientx64 \
>                 evaluated to 1
> Apr 25 13:53:17 hellbox kea-dhcp4[16858]: INFO  DHCP4_LEASE_ADVERT [hwtype=1 \
> 00:e0:4c:68:0a:c1], cid=[no info], tid=0x2223e0e3: lease 172.20.19.150 will be \
>                 advertised
> Apr 25 13:53:20 hellbox kea-dhcp4[16858]: INFO  EVAL_RESULT Expression pxeclientx64 \
>                 evaluated to 1
> Apr 25 13:53:20 hellbox kea-dhcp4[16858]: INFO  DHCP4_LEASE_ALLOC [hwtype=1 \
> 00:e0:4c:68:0a:c1], cid=[no info], tid=0x2223e0e3: lease 172.20.19.150 has been \
> allocated for 3600 seconds As we can see both matches: pxeclientx64 and the \
> reservation. The client successfully boots pxe. I don't understand why the client \
> successfully pxe boots. The client-class "pxeclientx64" is assigned to a pool. It \
> is neither assigned to the subnet4 { id: 1 } subnet declaration nor to the \
> reservation. What has precedence over what? How does inheritance work in kea?
> 
> Thanks,
> 
> --
> 
> Philipp
> 
> --
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