[Kea-users] [EXTERNAL] Re: Need to have DHCP Relay in order for Kea to work...?

Sat Aug 3 14:15:57 UTC 2024

Move your reservation clauses into the proper subnets.
Here's what I do (the reservation files are the ones ending in _res.conf).
Ex:
===========================================
<snip>
"reservation-mode": "out-of-pool",
<snip>
    "subnet4": [
      {
        "id": 1,
        "subnet": "172.27.12.0/24",
        "pools": [ { "pool": "172.27.12.240 - 172.27.12.248" } ],
       "option-data": [
              {
                "name": "routers",
                "data": "172.27.12.1"
              },
              {
                "code": 121,
                "data": "24, 192, 168, 77, 172, 27, 12, 254, 24, 192,
168, 88, 172, 27, 12, 254, 24, 192, 168, 111, 172, 27, 12, 254, 24,
192, 168, 222, 172, 27, 12, 254"
              }
            ],
           <?include "/etc/kea/id1_res.conf"?>
      },
      {
        "id": 2,
        "subnet": "192.168.77.0/24",
        "pools": [ { "pool": "192.168.77.50 - 192.168.77.55" } ],
        "option-data": [
              {
                "name": "routers",
                "data": "192.168.77.254",
                "always-send": true
              }
            ],
           <?include "/etc/kea/77_id2_res.conf"?>
       },
===========================================


On Sat, Aug 3, 2024 at 6:42 AM Ubence Quevedo <thatrat at gmail.com> wrote:
>
> Looking at this further, I think my problem now has to do with the various host reservation options available.
>
> I have a few pools that are in each vlan that are available for anything that doesn't have a reservation.
>
> Most everything on my network has reservations for each of the vlans.
>
> The documentation is a little confusing on which option I should be choosing with not enough examples.
>
> What I've been looking at:
> https://kea.readthedocs.io/en/kea-2.6.1/arm/dhcp4-srv.html#fine-tuning-dhcpv4-host-reservation
>
> Since my reservations aren't defined in each of the subnets, but rather globally, I think I want this configuration:
> {
>   "Dhcp4": {
>     "reservations-global": true,
>     "reservations-in-subnet": false
>   }
> }
>
> I have the reservation files split out into json files similar to what the older dhcpd allowed to make for a cleaner configuration file:
>     "reservations": [
>         <?include "/etc/kea/01-dhcp_network.json"?>
>         <?include "/etc/kea/02-dhcp_user_systems.json"?>
>         <?include "/etc/kea/03-dhcp_ent.json"?>
>         <?include "/etc/kea/04-dhcp_servers.json"?>
>         <?include "/etc/kea/05-dhcp_iot.json"?>
>     ],
>
> Any advice on how to make it so that the host reservation works properly without relying on DHCP relay/UDP to give clients the appropriate address?
>
> Or do I already have this configured properly and I have to use a DHCP relay to make this work as I'm expecting?
>
> -Ubence
>
> On Sat, Aug 3, 2024 at 2:56 AM Ubence Quevedo <thatrat at gmail.com> wrote:
>>
>> Turning off the udp dhcp-socket-type and disabling the DHCP relay did work in that my systems were getting IP addresses assigned to them.
>>
>> However, even though I have reservations for just about everything in my network, the systems were getting IP addresses out of scope from their reservations.
>>
>> A system on vlan11 with an IP address of 192.168.11.XXX was getting assigned an address of 192.168.10.XXX.
>>
>> I'll have to dig into the logs to see why this might be, but it could also be because I don't have the firewall rules tightened between the vlans and traffic from one vlan can get to another.
>>
>> Once I set things back to the udp dhcp-socket-type and turned the DHCP relay back on, the systems got the appropriate address.
>>
>> I just assumed that since I had interfaces on each of the vlans that each system on its respective vlan would get its appropriate address.
>>
>> Unless I might have something else misconfigured?
>>
>> -Ubence
>>
>> On Fri, Aug 2, 2024 at 1:18 PM Ubence Quevedo (thatrat) <thatrat at gmail.com> wrote:
>>>
>>> Yes, here’s the interface-config section that I have defined:
>>>     "interfaces-config": {
>>>         "interfaces": [ "eno2/192.168.10.3","eno2.11/192.168.11.3","eno2.12/192.168.12.3" ],
>>>         "dhcp-socket-type": "udp",
>>>         "service-sockets-max-retries": 5,
>>>         "service-sockets-retry-wait-time": 5000
>>>     },
>>>
>>> …and from further reading on the interfaces-config section, specifically the dhcp-socket-type configuration:
>>> Using UDP sockets automatically disables the reception of broadcast packets from directly connected clients. This effectively means that UDP sockets can be used for relayed traffic only. When using raw sockets, both the traffic from the directly connected clients and the relayed traffic are handled.
>>>
>>> So…I’m doing this to myself. 😖
>>>
>>> I’m assuming I should either remove this line or set it to raw, which are effectively the same thing I believe [I like to have fully qualified configs when possible to take out the guess work].
>>>
>>> Once I do this though and restart the service, I think I can disable the relay and then the interfaces should start picking up the traffic.
>>>
>>> -Ubence
>>>
>>> On Aug 2, 2024, at 8:34 AM, Sonic <sonicsmith at gmail.com> wrote:
>>>
>>> Are you by chance using:
>>>  "dhcp-socket-type": "udp"
>>> for the interfaces in question?
>>>
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