====== Ubuntu Desktop - Network - Use /etc/network/interfaces instead of netplan ======

Ubuntu 18.04 stopped using the classic /etc/init.d/networking and /etc/network/interfaces method of configuring the network and switched to some thing called [[https://netplan.io/|netplan]]. 

----

===== Reinstall the ifupdown package =====

<code bash>
sudo apt update
sudo apt install ifupdown
</code>

----

===== Configure your /etc/network/interfaces file with configuration stanzas =====

Example:


source /etc/network/interfaces.d/*

<file bash>
# 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 1.1.1.1 1.0.0.1
</file>

----

===== Make the configuration effective (no reboot needed) =====

<code bash>
sudo ifdown --force enp0s3 lo && ifup -a
sudo systemctl unmask networking
sudo systemctl enable networking
sudo systemctl restart networking
</code>

----

===== Disable and remove the unwanted services =====

<code bash>
sudo systemctl stop systemd-networkd.socket systemd-networkd \
networkd-dispatcher systemd-networkd-wait-online

sudo systemctl disable systemd-networkd.socket systemd-networkd \
networkd-dispatcher systemd-networkd-wait-online

sudo systemctl mask systemd-networkd.socket systemd-networkd \
networkd-dispatcher systemd-networkd-wait-online

sudo apt --assume-yes purge nplan netplan.io
</code>

Adjust the values according to your system (network, interface name...).

----

===== 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:

<file bash /etc/systemd/resolved.conf>
....
DNS=1.1.1.1 1.0.0.1
....
</file>

and then restart the systemd-resolved service once done:

<code bash>
sudo systemctl restart systemd-resolved
</code>

The DNS entries in the ifupdown INTERFACES(5) file, as shown above, are only relevant if you make use of RESOLVCONF(8) or similar.

----

===== References =====

https://netplan.io/

https://netplan.io/faq#how-to-go-back-to-ifupdown