How to configure a Dedibox failover IP on Debian and Ubuntu

Reviewed on February 13, 2025

This guide provides step-by-step instructions for configuring a Dedibox failover IP on Debian and Ubuntu Linux. A failover IP is a secondary IP address that can be assigned to your server.

Before you start

To complete the actions presented below, you must have:

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

Failover IP configuration on Debian

Connect to your server using SSH and open the network configuration file /etc/network/interfaces in a text editor, such as nano:
```
nano /etc/network/interfaces
```

Add the failover IP to the configuration as shown in the following example:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
iface eth0 inet static
    address 195.154.123.123
    netmask 255.255.255.0
    gateway 195.154.123.1
auto eth0:0
iface eth0:0 inet static
    address ip_failover
    netmask 255.255.255.255

Note

The interface name (eth0 in this example) may vary depending on your OS version and system configuration. Use the ifconfig command to determine the name of your primary network interface.

Save the file and exit the editor. Bring up the interface using the following command:
```
ifup eth0:0
```

Failover IP configuration on Ubuntu (Netplan)

Since Ubuntu 18.04, Netplan has been the default network configuration system.

Disable cloud-init network configuration to prevent conflicts with Netplan:
```
sudo mkdir -p /etc/cloud/cloud.cfg.d
echo 'network: {config: disabled}' | sudo tee /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg
```
Important
This step is necessary to prevent cloud-init from overriding the Netplan configuration.

Backup the existing Netplan configuration and create a new file:

sudo cp /etc/netplan/50-cloud-init.yaml /etc/netplan/01-myplan.yaml
sudo mv /etc/netplan/50-cloud-init.yaml /etc/netplan/50-cloud-init.yaml-backup

Edit the new Netplan configuration file /etc/netplan/01-myplan.yaml using nano:

network:
  renderer: networkd
  ethernets:
    enp5s0:
      critical: true
      dhcp-identifier: mac
      dhcp4: false
      dhcp6: false
      addresses:
        - 51.111.222.333/24  # Server main IP (/24)
        - 212.111.222.333/32  # Alternate IPs / IP redirects (/32)
        - 212.111.222.334/32
        - 212.111.222.335/32
      routes:
        - to: 0.0.0.0/0
          via: 62.210.0.1
          metric: 1
          on-link: true
      nameservers:
        addresses:
          - 51.159.69.156
          - 51.159.69.162
    enp6s0:
      dhcp4: true
      dhcp4-overrides:
        use-routes: false
      routes:
        - to: 10.88.0.0/13  # Use appropriate IP/gateway from DHCP
          via: 10.89.23.129
version: 2

Tip

Ensure that indentation and formatting are correct to avoid YAML syntax errors.

Run the following command to test the configuration:
```
sudo netplan try
```
If everything works as expected, apply the configuration:
```
sudo netplan apply
```
Important
If there is an error in your configuration, it might render your network inaccessible. You may need to revert changes using KVM/IPMI access.

Troubleshooting

If you encounter issues with your network configuration, check the logs using:

sudo journalctl -u systemd-networkd --no-pager

You can also refer to the official Canonical repository for more Netplan examples and troubleshooting guides.