The following procedure works for Ubuntu 18.04 (Bionic Beaver)
I. Reinstall the ifupdown package:
# apt-get update # apt-get install ifupdown
II. Configure your /etc/network/interfaces file with configuration stanzas such as:
source /etc/network/interfaces.d/* # The loopback network interface auto lo iface lo inet loopback allow-hotplug enp0s3 auto enp0s3 iface enp0s3 inet static address 192.168.1.133 netmask 255.255.255.0 broadcast 192.168.1.255 gateway 192.168.1.1 # Only relevant if you make use of RESOLVCONF(8) # or similar... dns-nameservers 220.127.116.11 18.104.22.168
III. Make the configuration effective (no reboot needed):
# ifdown --force enp0s3 lo && ifup -a # systemctl unmask networking # systemctl enable networking # systemctl restart networking
IV. Disable and remove the unwanted services:
# systemctl stop systemd-networkd.socket systemd-networkd \ networkd-dispatcher systemd-networkd-wait-online # systemctl disable systemd-networkd.socket systemd-networkd \ networkd-dispatcher systemd-networkd-wait-online # systemctl mask systemd-networkd.socket systemd-networkd \ networkd-dispatcher systemd-networkd-wait-online # apt-get --assume-yes purge nplan netplan.io
Then, you’re done.
Note: You MUST, of course, adapt the values according to your system (network, interface name…).
V. DNS Resolver
Because Ubuntu Bionic Beaver (18.04) make use of the DNS stub resolver as provided by SYSTEMD-RESOLVED.SERVICE(8), you SHOULD also add the DNS to contact into the /etc/systemd/resolved.conf file. For instance:
.... DNS=22.214.171.124 126.96.36.199 ....
and then restart the systemd-resolved service once done:
# systemctl restart systemd-resolved
The DNS entries in the ifupdown INTERFACES(5) file, as shown above, are only relevant if you make use of RESOLVCONF(8) or similar.
If you copy something, it would be worth mentioning. https://askubuntu.com/questions/1031709/ubuntu-18-04-switch-back-to-etc-network-interfaces
I usually keep the content credit source if it’s collected or copied from somewhere else. If you read the other posts you should find them in usual footer credit content src link. However, sometimes the source link are a bit lost while I work multiple workstation terminal. I’m updating this particular post.