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Configure a Failover IP

This guide explains how to configure a Failover IP on your Linux VPS. Choose the section matching your distribution and its network manager.

Prerequisites​

  • SSH root or sudo access
  • A Failover IP assigned to your VPS
  • Linux system (Debian, Ubuntu, AlmaLinux, Rocky Linux, Fedora…)

Configuration with ifupdown (/etc/network/interfaces)​

Legacy method used on Debian and older Ubuntu versions. If your system uses Netplan (Ubuntu 18.04+), refer to the next section.

  1. Disable automatic network configuration:

    sudo nano /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg

    Add this line:

    network: {config: disabled}

  2. Configure the virtual interface:

    sudo nano /etc/network/interfaces.d/50-cloud-init

    Add these lines:

    # Failover IP interface
    auto eth0:1
    iface eth0:1 inet static
        address YOUR_FAILOVER_IP
        netmask 255.255.255.255

  3. Restart the network service:

    sudo systemctl restart networking

Configuration with Netplan (Ubuntu 18.04+)​

On recent Ubuntu-based systems, the network is managed by Netplan rather than by /etc/network/interfaces. Use this method instead of the previous section.

  1. Identify your network interface name:

    ip a

    (for example eth0, ens3 or enp1s0)

  2. Edit the Netplan configuration file:

    sudo nano /etc/netplan/50-cloud-init.yaml

    Add the Failover IP to your interface, keeping the existing configuration (mind the YAML indentation, 2 spaces):

    network:
      version: 2
      ethernets:
        eth0:
          addresses:
            - YOUR_FAILOVER_IP/32

  3. Apply the configuration:

    sudo netplan apply

Tip: use sudo netplan try instead of netplan apply to test; the configuration is automatically rolled back after 120 seconds if you don't confirm it, which prevents losing SSH access in case of an error.

Configuration with network-scripts (AlmaLinux / Rocky Linux 8 and 9)​

On RHEL-based distributions (AlmaLinux, Rocky Linux 8 and 9), create a dedicated configuration file for the virtual interface.

  1. Identify your network interface name:

    ip a

    (for example eth0 or ens3)

  2. Create the alias configuration file:

    sudo nano /etc/sysconfig/network-scripts/ifcfg-eth0:1

    Add these lines:

    DEVICE=eth0:1
    BOOTPROTO=static
    IPADDR=YOUR_FAILOVER_IP
    NETMASK=255.255.255.255
    ONBOOT=yes

  3. Restart the network service:

    sudo systemctl restart NetworkManager

Configuration with NetworkManager (Fedora, AlmaLinux, Rocky Linux)​

On Fedora and recent versions of AlmaLinux and Rocky Linux, the network is managed directly through NetworkManager connection files.

  1. Identify your interface connection file:

    ls /etc/NetworkManager/system-connections/

  2. Edit the matching connection file (for example cloud-init-eth0.nmconnection):

    sudo nano /etc/NetworkManager/system-connections/cloud-init-eth0.nmconnection

    In the [ipv4] section, add the Failover IP:

    [ipv4]
    method=auto
    address1=YOUR_FAILOVER_IP/32

  3. Restart NetworkManager:

    sudo systemctl restart NetworkManager

Verification​

  1. Verify that the IP is properly configured:

    ip addr show

  2. Test connectivity:

    ping -I YOUR_FAILOVER_IP 8.8.8.8

Best practices​

  • Document your network configurations
  • Test the configuration before any production deployment
  • Keep a backup of configuration files
  • Configure alerts in case of connectivity loss

Troubleshooting​

  • Check system logs: sudo journalctl -xe
  • Check network configuration: sudo networkctl status
  • Make sure the IP is properly assigned to your VPS
  • Verify there is no IP conflict
  • As a last resort, boot your server in rescue mode and add the IP on the fly: ip addr add YOUR_FAILOVER_IP/32 dev eth0

Important notes​

  • The Failover IP must be configured with a network mask 255.255.255.255
  • Some services may require reconfiguration to use the new IP
  • Configuration may vary depending on your Linux distribution