How to configure the dhclient

Reviewed on 20 May 2024 • Published on 03 August 2021

dhcpv6
duid
autostart
dhcp
dhclient

Important

It is now recommended to use the systemd-networkd DHCP client as the one provided by the internet Systems Consortium, dhclient, has reached its End of Life (EOL) on 5th October 2022.

Before you start

To complete the actions presented below, you must have:

A Dedibox account logged into the console
A Dedibox dedicated server
Requested a /48 IPv6 prefix

Important

For servers supporting IPv6 SLAAC, it is important to enable SLAAC to ensure the proper functioning of DHCPv6. If SLAAC is disabled, the server won’t be able to learn its IPv6 default route.

How to set the DUID of your subnet

Log into your server using SSH.

Open the file /etc/dhcp/dhclient6.conf in a text editor, for example: nano, and edit it as shown below:

interface "eno1" {
    send dhcp6.client-id DUID;
}

Make sure to adapt the interface name (eno1) to the internet interface name of your system, and replace DUID with the DUID of your prefix.

How to autostart the DHCPv6 client during system boot

To enable the automatic start of the DHCPv6 client during system boot, a systemd service is required.

Log into your server using SSH.

Open the file /etc/systemd/system/dhclient.service in a text editor, for example: nano, and edit it as shown below:

[Unit]
Description=dhclient for sending DUID IPv6
After=network-online.target
Wants=network-online.target
[Service]
Restart=always
RestartSec=10
Type=forking
ExecStart=/sbin/dhclient -cf /etc/dhcp/dhclient6.conf -6 -P -v eno1
ExecStop=/sbin/dhclient -x -pf /var/run/dhclient6.pid
[Install]
WantedBy=network.target

Tip

The path to the dhclient binary may vary depending on your OS. To see the exact path for your system, use the following command: which dhclient.

Enable the service so it will start automatically at each reboot of the machine:

sudo systemctl enable dhclient.service