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

Tue Jul 16 11:04:36 UTC 2024

Thanks for all of the responses on this.

The system that is the Kea DHCP server [an Ubuntu system] has one interface
that I've setup with vlan interfaces.

I can access these other interfaces and verified through nmap that port 67
is open on all interfaces.

I can't seem to find any kind of ip helper option in the Unifi Controller
[v8.2.93 running on a virtual Ubuntu system].

I've reconfigured the DHCP Relay on the pfSense to point to all of the
interfaces, and I'm now seeing the traffic I'm expecting to see, which is
fine since. understand a little better of what might be going on.

Just a little confused as to why the broadcast traffic for DHCP requests
doesn't seem to be picked up on the vlan interfaces on the server.

I do have another question, but I'll put that in a separate post since it
doesn't seem to be related to this question at hand.

-Ubence

On Mon, Jul 15, 2024 at 6:59 AM Joe Craig <JCraig at applieddigital.com> wrote:

> Question about the setup. On the network switches that the DHCP requests
> would hit first, do you have IP Helpers configured? In my experience that’s
> what I’ve had to do to ensure that the packets make it to the DHCP server
> without a DHCP Relay. I’m in an environment where I cannot deploy a DHCP
> Relay service, so I am leveraging the IP Helpers on an L3 switch to forward
> those requests. This is passing through an Cisco firewall and all that.
> Hope that helps.
>
>
>
> Thanks,
>
>
>
> *Joseph Craig*
> Systems Engineer
>
>
>
>
> *From:* Kea-users <kea-users-bounces at lists.isc.org> *On Behalf Of *DDFR |
> Ronald Blaas
> *Sent:* Monday, July 15, 2024 2:15 AM
> *To:* kea-users at lists.isc.org
> *Subject:* [EXTERNAL] Re: [Kea-users] Need to have DHCP Relay in order
> for Kea to work...?
>
>
>
> You don't often get email from ronald.blaas at ddfr.nl. Learn why this is
> important <https://aka.ms/LearnAboutSenderIdentification>
>
> Not really sure how you have your network setup.
>
>
>
> But in my belief, if you want dhcp to work without RELAY you have to make
> sure your DHCP server is directly connected to all the LANs. So your DHCP
> server will need to have multiple Nics.
>
>
>
> Is  there a particular reason you do not want to have a dhcp relay?
>
>
>
> I have a kinda similar setup and am using DHCP relay. It is operating as
> expected and without problems.
>
>
>
> It is also wise to share the output of your log file with the error you
> are receiving.
>
> Tis helps in pinpointing the problem.
>
>
>
> Regards
>
>
>
>
>
> Ronald
>
>
>
>
> ------------------------------
>
> *From:* Kea-users <kea-users-bounces at lists.isc.org> on behalf of Ubence
> Quevedo <thatrat at gmail.com>
> *Sent:* Monday, July 15, 2024 00:26
> *To:* kea-users at lists.isc.org <kea-users at lists.isc.org>
> *Subject:* [Kea-users] Need to have DHCP Relay in order for Kea to
> work...?
>
>
>
> U ontvangt niet vaak e-mail van thatrat at gmail.com. Meer informatie over
> waarom dit belangrijk is <https://aka.ms/LearnAboutSenderIdentification>
>
> Hi Everyone,
>
>
>
> I’ve been using Kea for just under a year for a home setup on a Linux
> Ubuntu server.  I switched from isc dhcp since it was end of life.  My
> setup has a lot of MAC address reservations with some general pools for
> systems that don’t have IP reservations.
>
>
>
> I also have a few vlans set up with the reservations for devices on each
> of the vlans.  I’m using pfSense as my gateway with some Unifi equipment
> that is vlan aware.
>
>
>
> I’m running into an issue and I’m not sure why and would love some advice
> on how to look into this.
>
>
>
> I have the interfaces on the system setup that is running Kea, to
> advertise on the untagged network [mostly some servers], vlan 11 [user
> systems], and vlan12 [IoT devices].
>
>
>
> I don’t have the firewall in pfSense to block traffic between these
> networks yet, so they can all freely talk to each other.
>
>
>
> Even though I have my Kea configured to advertise on all of the interfaces
> [untagged, 11, 12], I can’t seem to get anything to work unless I have the
> DHCP Relay service setup on the pfSense device to redirect all DHCP traffic
> to the Kea system’s untagged IP address [192.168.10.3].
>
>
>
> I can verify through nmap that udp port 67 is running on all three
> interfaces.
>
>
>
> If I turn off the DHCP Relay service, I was expecting the interfaces to
> pick up on the DHCP requests from devices on all of these networks.
>
>
>
> This doesn’t happen and devices don’t get addresses.  I’ve even watched
> the logs I’ve split out and nothing is written for the duration that the
> relay service is turned off.  As soon as I turn it back on, I start seeing
> traffic again.
>
>
>
> I’m running Kea 2.6.0.
>
>
>
> I’d love to turn the DHCP Relay off to then try to troubleshoot another
> issue I’m having with bridging interfaces to VMs and then having the VM
> interface assigned to a vlan other than the bridged interface.  It seems to
> work for something else I’m doing, but just trying to rule some things
> out.  Probably another post if I can figure out why the DHCP Relay seems to
> need to be on.
>
>
>
> Any ideas why I need the DHCP Relay service on another device even though
> all of the interfaces on each respective vlan are configured to listen for
> dhcp requests?
>
>
>
> -Ubence
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