Kea DHCP is the current Dynamic Host Configuration Protocol server of the Internet Systems Consortium (ISC).

Installation

Install the kea package. For additional documentation install kea-docs.

Optional dependencies are:

• krb5 for Kerberos support

• mariadb as database backend

• postgresql as database backend

• python to use Kea Shell

Configuration

The configuration files are located under /etc/kea. The content of the configuration files uses JSON structures. For special configurations that are not yet included in the following examples, please refer to the Kea documentation.

IPv4 DHCP

To use DHCP for IPv4, the configuration file /etc/kea/kea-dhcp4.conf must be adapted and the service kea-dhcp4.service must be activated and started.

Make sure to assign a static IP address to the interface on which Kea is listen on.

Example single subnet configuration

Assumptions for the example:

• The net is 192.168.0.0/24

• DNS server has the IP 192.168.0.1/24

• Gateway has the IP 192.168.0.254/24

• Static IP of the DHCP server network interface eth0 is 192.168.0.253/24

• Kea should provide IPs from 192.168.0.100/24 to 192.168.0.199/24

A minimal configuration file /etc/kea/kea-dhcp4.conf could look like:

{
    "Dhcp4": {
        "interfaces-config": {
            "interfaces": [ "eth0/192.168.0.253" ],
            "dhcp-socket-type": "raw"
        },

        "subnet4": [
            {
                "id": 1,
                "subnet": "192.168.0.0/24",
                "pools": [ { "pool": "192.168.0.100 - 192.168.0.199" } ],
                "option-data": [
                    {
                        "name": "routers",
                        "data": "192.168.0.254"
                    },
                    {
                        "name": "domain-name-servers",
                        "data": "192.168.0.1"
                    }
                ]
            }
        ]
    }
}

/etc/kea/kea-dhcp4.conf

Example multiple subnet configuration

Assumptions for the example:

The networks are:

• Network 1: 192.168.0.0/24 (is a standard physical network)

• Network 2: 192.168.1.0/24 (is a virtual VLAN network)

DNS servers are:

• Network 1 hosts it's own DNS server at IP: 192.168.0.1

• Network 2 uses upstream Google DNS: 8.8.8.8 & 8.8.4.4

Gateways are:

• Network 1: 192.168.0.254/24

• Network 2: 192.168.1.254/24

Static IP of the DHCP servers are:

• Network 1: network interface eth0 is 192.168.0.253

• Network 2: network interface eth0.100 is 192.168.1.253

Kea should provide IPs:

• Network 1: from 192.168.0.100/24 to 192.168.0.199/24

• Network 2: from 192.168.1.2/24 to 192.168.1.252/24

You have a couple of static IPs defined:

• Network 1: Has two special phones with static leases 192.168.0.10 && 192.168.0.11

• You want to enable maximum debug logging for IPv4 in order to troubleshoot any problems with IP reservation

A more complex configuration file /etc/kea/kea-dhcp4.conf could look like:

{
    "Dhcp4": {
        "interfaces-config": {
            "interfaces": [ "eth0/192.168.0.253", "eth0.100/192.168.1.253" ],
            "dhcp-socket-type": "raw"
        },
        "loggers": [
          {
            "name": "kea-dhcp4",
            "severity": "DEBUG",
            "debuglevel": 99,
            "output_options": [
              {
                "output": "stdout"
              }
            ]
          }
        ],
        "subnet4": [
            {
                "id": 1,
                "subnet": "192.168.0.0/24",
                "interface": "eth0",
                "pools": [ { "pool": "192.168.0.100 - 192.168.0.199" } ],
                "option-data": [
                    {
                        "name": "routers",
                        "data": "192.168.0.254"
                    },
                    {
                        "name": "domain-name-servers",
                        "data": "192.168.0.1"
                    }
                ],
                "reservations": [
                {
                    "hostname": "phone1",
                    "hw-address": "1a:1b:1c:1d:1e:1f",
                    "ip-address": "192.168.0.10"
                },
                {
                    "hostname": "phone2",
                    "client-id": "01:11:22:33:44:55:66",
                    "ip-address": "192.168.0.11"
                }
            ]
            },
            {
                "id": 2,
                "subnet": "192.168.1.0/24",
                "interface": "eth0.100",
                "pools": [ { "pool": "192.168.1.2 - 192.168.1.252" } ],
                "option-data": [
                    {
                        "name": "routers",
                        "data": "192.168.1.254"
                    },
                    {
                        "name": "domain-name-servers",
                        "data": "8.8.8.8, 8.8.4.4"
                    }
                ]
            }
        ]
    }
}

/etc/kea/kea-dhcp4.conf

Usage

Kea includes four systemd unit files:The configuration file for DHCPv4 can be checked for errors by running the command:

# kea-dhcp4 -t /etc/kea/kea-dhcp4.conf

If everything looks good, then you can enable/start kea-dhcp4.service.