Network configuration with Netplan on Ubuntu on a Scaleway Dedibox

Reviewed on 26 August 2024 • Published on 20 August 2021

Since the release of its version 18.04, Bionic Beaver, Ubuntu has switched to Netplan for the network interface configuration. It is a YAML based configuration system, which simplifies the configuration process.

Before you start

To complete the actions presented below, you must have:

A Dedibox account logged into the console
Created and installed a dedicated server

Configuration files

This tool replaces the /etc/network/interfaces configuration file previously used to configure the network interfaces on Ubuntu.

The configuration files are now YAML files located in /etc/netplan/*.yaml.

Important

Make sure you respect the YAML standards when you edit the file, as syntax errors might cause errors in your configuration.

The 01-netcfg.yaml file is used to configure the first interface. Below, you can find the default configuration for an interface using DHCP:

# This file describes the network interfaces available on your system
# For more information, see netplan(5).
network:
  version: 2
  renderer: networkd
  ethernets:
    enp1s0f0:
      dhcp4: yes

Following, you can see a list of the most common configuration options and a description of how they are used.

Option	Example	Description
addresses	192.168.1.2/24, 62.210.123.123/32	A list of IP addresses to be assigned to an interface. The format uses CIDR notation.
gateway4	192.168.1.1	The IP address of your local IPv4 gateway.
dhcp4	true	Set whether DHCP is enabled for IPv4 – true of false
dhcp6	true	Set whether DHCP is enabled for IPv6 – true or false

Configuring a failover IP with Netplan

To configure a failover IP, you must edit the file /etc/netplan/01-netcfg.yaml and configure static networking for your server. The IP addresses have to be written with their CIDR notation. The netmask is /24 for the principal IP of the server and /32 for each failover IP. Your configuration file should look like in the following example:

network:
  version: 2
  renderer: networkd
  ethernets:
    enp1s0f0:
      addresses: [163.172.123.123/24, 212.83.123.123/32]
      gateway4: 163.172.123.1
      nameservers:
        addresses: [ "51.159.47.28", "51.159.47.26" ]

Tip

Replace the DNS cache servers in the example above (51.159.47.28 and 51.159.47.26) with the nameservers available in the same datacenter as your server for optimal latency.

Once you have edited and saved the file, you can reload the configuration with the following command:

sudo netplan apply

Configuring a failover IP for virtual machines

When configuring a failover IP in a virtual machine, you must specify which route will be used by the VM. Your configuration file should look like the following example:

    network:
    ethernets:
        ens18:
            addresses:
            - [ "fail.over.ip.address/32" ]
            nameservers:
                addresses: [ "51.159.47.28", "51.159.47.26" ] # Replace the IP of the DNS cache server with the one located in the same physical location as your machine for optimal performances (https://www.scaleway.com/en/docs/console/account/reference-content/scaleway-network-information/#dns-cache-servers/)
            routes:
            -   to: default
                via: 62.210.0.1
            -   to: 62.210.0.1/32
                via: fail.over.ip.address
                scope: link
    version: 2

Tip

Replace the DNS cache servers in the example above (51.159.47.28 and 51.159.47.26) with the nameservers available in the same datacenter as your server for optimal latency.