Setting up a private network for VPS+ or migrated Cloud Servers (Ubuntu 24.04, Ubuntu 26.04, Debian 12 with Netplan, and Debian 13)

This step is only required for Debian 12: To check whether your server is already using Netplan for network configuration, enter the following commands:

• Change to the /etc/netplan directory.

  [root@localhost ~]# cd /etc/netplan

• Check whether there is already a configuration file in this directory. To do this, enter the following command:

  [root@localhost ~]# ls

• Make a note of the name of the configuration file.

• To display the default gateway for the active interface, enter the following command:
  
  IPv4:

  [root@localhost ~]# ip route show | grep 'default'

  
  IPv6:

  [root@localhost ~]# ip -6 route show | grep 'default'

• Make a note of the IP addresses of the gateways. These are listed immediately after the ‘default via’ section. Example:
  
  IPv4 gateway

  [root@localhost ~]# ip route show | grep ‘default’ default via 195.20.234.1 dev ens6 proto dhcp src 195.20.234.94 metric 100

  
  IPv6 gateway

  [root@localhost ~]# ip -6 route show | grep 'default' default via fe80::1 dev ens192 proto ra metric 100 expires 4sec pref high

  In this example, fe80::1 is the IPv6 gateway.

• Check whether there is already a configuration file in this directory. To do this, enter the following commands:

  [root@localhost ~]# cd /etc/netplan

  [root@localhost ~]# ls /etc/netplan

• If there is a configuration file in this directory, rename it. To do this, enter the following command and adapt the placeholders.

  [root@localhost ~]# mv OLD_CONFIGURATION_FILE.yaml OLD_CONFIGURATION_FILE.yaml.old

  Example:

  [root@localhost ~]# mv 50-cloud-init.yaml 50-cloud-init.yaml.old

• Create the file /etc/netplan/01-netcfg.yaml using the vi editor. To do this, enter the following command:

  [root@localhost ~]# vi /etc/netplan/01-netcfg.yaml

• To use a server on a private network, you must manually assign an IP address during the manual configuration of the network interface, so that the server can be accessed on the private network. This IP address cannot be routed to public networks. To configure the desired static IP address, enter the following information:

  network:
  version: 2
  renderer: networkd
  ethernets:
     NETWORK_INTERFACE:
      addresses:
        - MAIN_IPV4_ADDRESS/32
        - ADDITIONAL_IPV4_ADDRESS/32
        - MAIN_IPV6_ADDRESS/64
        - ADDITIONAL_IPV6_ADDRESS_1/64
      nameservers:
        addresses:
          - NAMESERVER_1_IP_ADDRESS
          - NAMESERVER_2_IP_ADDRESS
      routes:
        - on-link: true
          to: default
          via: DEFAULT_GATEWAY_OF_THE_ACTIVE_INTERFACE
     PRIVATE_NETWORK_INTERFACE:
      dhcp4: no
      addresses:
        - SERVER_IP_ADDRESS_IN_PRIVATE_NETWORK/24
      nameservers:
        addresses:
          - NAMESERVER_1_IP_ADDRESS
          - NAMESERVER_2_IP_ADDRESS

  Example:

  network:
  version: 2
  renderer: networkd
  ethernets:
    ens6:
      addresses:
        - 85.215.124.167/32
        - 212.227.250.35/32
        - 2a02:2479:7:e00::1/64
        - 2a02:2479:7:e00::/64
      nameservers:
        addresses:
          - 212.227.123.16
          - 212.227.123.17
      routes:
        - on-link: true
          to: default
          via: 10.255.255.1
    ens7:
      dhcp4: no
      addresses:
        - 192.168.1.2/24
      nameservers:
        addresses:
          - 212.227.123.16
          - 212.227.123.17

• Press the [ESC] key to exit edit mode.
• To exit vi and save the file, type the command :wq and then press the Enter key.

• To change the permissions of the new configuration file so that it can only be read and modified by the root account, adapt the following command and then enter it:

  [root@localhost ~]# sudo chmod 600 /etc/netplan/CONFIGURATION_FILE.yaml

  Example:

  [root@localhost ~]# sudo chmod 600 /etc/netplan/01-netcfg.yaml

• To check the configuration file, enter the following command:

  [root@localhost ~]# netplan --debug apply

The server can now be accessed via the private network.