Before you start, you maybe want to install and configure neovim that will help you write the kea json based configuration files: NeoVIM Configuration

Migrate from ISC-DHCP Server

Install the migration tool with:

pkg install keame

To migrate your old IPv4 configuration do:

cd /usr/local/etc/kea
keama -4 -i ../dhcpd.conf -o kea-dhcp4.conf

The migration tool does not add an interface definition, that is something you need to do manually. To find the interface isc-dhpcd is using do:

cat /etc/rc.conf | grep dhcpd_ifaces

In my case it is em0 so add to your config:

{
  "Dhcp4": {
    // Add names of your network interfaces to listen on.
    "interfaces-config": {
      "interfaces": [ "em0" ]
    },
    //...
  }
}

Compare the file now with the kea-dhcp4.conf.sample you maybe want to transform some comments into user-context:

...
"user-context": {
  "comment": "comment",
  "room": "Roomname"
}
...

so this information is attached to the record and can be displayed all other connected systems.

Check config

kea-dhcp4 -t kea-dhcp4.conf