Setting up a private network for migrated Cloud Servers (Ubuntu 20.04, 22.04, 24.04, and Debian 12 with Netplan)

To check whether your server is already using Netplan for the network configuration, complete the following.

• 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 of the active interface, enter the following command:
  
  IPv4:

  root@ubuntu:~# ip route show | grep 'default'

  
  IPv6:

  root@ubuntu:~# ip -6 route show | grep 'default'

• Note the IP addresses of the gateways. These are listed directly after the default via part. Example:
  
  IPv4 Gateway

  root@ubuntu:~# 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@ubuntu:~# 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 replace 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 with the vi editor. To do this, enter the following command:

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

• To be able to use a server in a private network, it's necessary to manually configure the network interface and assign a unique IP address to it. This IP address will enable communication with the server within the private network. This IP address cannot be routed to public networks. To configure the desired static IP address, add 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:
  - IP_ADDRESS_OF_NAMESERVER_1
  - IP_ADDRESS_OF_NAMESERVER_2
  routes:
  - on-link: true
  to: default
  via: STANDARD_GATEWAY_OF_THE_ACTIVE_INTERFACE
  NETWORK_INTERFACE_OF_THE_PRIVATE_NETWORK:
  dhcp4: no
  addresses:
  - IP_ADDRESS_OF_SERVER_IN_THE_PRIVATE_NETWORK/24
  nameservers:
  addresses:
  - IP_ADDRESS_OF_NAMESERVER 1
  - IP_ADDRESS_OF_NAMESERVER 2

  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 input mode.
• To exit vi and save the file, enter the command :wq and then press Enter.

• To change the permissions of the new configuration file to read/write for only the root account, edit 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 apply the configuration file, enter the following command:

  root@localhost:~# netplan --debug apply

The server is now accessible in the private network.