Setting up a private network for migrated Cloud Servers (Debian 11)

For migrated Cloud Servers

This article shows you how to configure the private network settings for migrated Cloud Servers with Debian 11.

In a private network, the servers communicate via local IPs that are not routed on the Internet. To be able to use a server in a private network, you must first assign the server in the Cloud Panel to the desired private network. As soon as the server has been assigned to the desired private network, an additional, unconfigured network interface is available on it. You must configure this network interface on the server. To do this, you must create the relevant configuration files under /etc/systemd/network/. To do this, proceed as follows:

• To determine the correct hostname, enter the following command:

  root@debian:~# hostname

• Open the hosts file with the vi editor. To do this, enter the following command:

  root@debian:~# vi /etc/hosts

• Insert the following line with the correct hostname:

  127.0.1.1 HOSTNAME

  Example:

  127.0.1.1 debian

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

• Restart the hostname service. To do this, enter the following command:

  root@debian:~# sudo systemctl restart systemd-hostnamed

To set a symbolic link from /etc/resolv.conf to the stub resolver configuration file generated by systemd-resolved, enter the following command:

root@debian:~# ln -sf /run/systemd/resolve/stub-resolv.conf /etc/resolv.conf

If the DNS servers used are not displayed after entering the previous command, enter the following command:

root@debian:~# cat /var/lib/dhcp/dhclient.NAME_OF_NETWORK_INTERFACE.leases

Example:

root@debian:~# cat /var/lib/dhcp/dhclient.ens6.leases

The DNS servers used are then displayed. Example:

root@debian:~# cat /var/lib/dhcp/dhclient.ens6.leases
default-duid "\000\001\000\001/-\016r\002\001\021\271+1";
lease {
interface "ens6";
fixed-address 212.227.52.44;
option subnet-mask 255.255.255.255;
option routers 212.227.52.1;
option dhcp-lease-time 600;
option dhcp-message-type 5;
option domain-name-servers 212.227.123.16,212.227.123.17;
option dhcp-server-identifier 169.254.0.2;
option host-name "my-server-1";
renew 4 2025/01/30 13:31:51;
rebind 4 2025/01/30 13:31:51;
expire 4 2025/01/30 13:31:51;
}

• Create a .network file with the file name 20-private.network using the vi editor. Enter the following command:

  root@debian:~# vi /etc/systemd/network/20-private.network

• Insert the following information after replacing the placeholders:

  [Match]
  Name=NETWORK_INTERFACE
  
  [Network]
  Address=IPV4_ADDRESS_OF_PRIVATE_NETWORK/24

  Example:

  [Match]
  Name=ens7
  
  [Network]
  Address=192.168.1.2/24

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

• To check whether the desired IPv4 and IPv6 addresses have been configured correctly, enter the following command:

  root@debian:~# ip addr show

• To check whether the network interface for the private network has been configured correctly, send a ping to the IP address of another server that is assigned to the private network. Example:

  root@localhost:~# ping -c 1 192.168.1.3
  PING 192.168.2.1 (192.168.2.2) 56(84) bytes of data.
  64 bytes from 192.168.2.2: icmp_seq=1 ttl=64 time=0.176 ms
  64 bytes from 192.168.2.2: icmp_seq=2 ttl=64 time=0.151 ms
  64 bytes from 192.168.2.2: icmp_seq=3 ttl=64 time=0.170 ms
  
  --- 192.168.1.3 ping statistics ---
  3 packets transmitted, 3 received, 0% packet loss, time 2050ms
  rtt min/avg/max/mdev = 0.151/0.165/0.176/0.018 ms

If the data packets are received by the server, the network interface has been properly configured for the private network.