Gfilui

Starting sometime around Ubuntu 18.04, the Ubuntu devs stopped using the classic /etc/init.d/networking and /etc/network/interfaces method of configuring the network and switched to some thing called netplan. This has made a lot of people very angry and been widely regarded as a bad move. Is it possible to remove netplan and use the correct /etc/network/interfaces method for configuring the network?

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
 dns-nameservers 8.8.8.8 8.8.4.4

III. Make the configuration effective (no reboot needed):

# ifdown --force enp0s3 lo && ifup -a

IV. Disable and remove the unwanted services:

# systemctl stop networkd-dispatcher
# systemctl disable networkd-dispatcher
# systemctl mask networkd-dispatcher
# apt-get purge nplan netplan.io

Then, you're done.

Note: You MUST of course adapt the values according your system (network, interface name...).

Why not just configure with netplan?

Well, as it is configured in 18.04-Desktop, it is a single line handing over control to all interfaces to NetworkManager.

While that is probably suitable for 95% of users, remember that NetworkManager is only run once you are logged in to a session.

Should you want your machine to act as a server/desktop, for example start serving files to local machines, acting as VNP server, etc... or anything "fancy" before anyone is ever logged in, just by the simple fact it is on, you will have trouble with how it is configured in standard 18.04-Desktop.

Of course, the alternative would be to use the server-Netplan configuration, which, as far as I have read (not checked by myself), hands control over to systemd-networkd instead.
In this case you'd better learn how systemd does things as a replacement of the old System V init.

Should you go this path, you still have to make change to the netplan yaml, since on a desktop version the control is given to NetworkManager.

The key is knowing that cloud.init is the real control program.

That being said the line in the netplan config file "optional: true" is mandatory.

Knowing that made it easy.

I just removed 01-network-manager-all.yaml and copied it to /root/save/.
Then put a known good config in place instead of it, 50-cloud-init.yaml: its contents follow:

network:
 version: 2
 renderer: networkd
 ethernets:
 eports:
 match: 
 name: enp*
 optional: true
 bonds:
 bond0:
 interfaces: [eports]
 addresses: [192.168.2.5/24]
 gateway4: 192.168.2.1
 nameservers:
 addresses: [127.0.0.1, 8.8.4.4] 
 parameters:
 mode: 0 
 mii-monitor-interval: 100

Then reboot and it should be working fine.

The known good config came from Configure bonded 802.3ad network using netplan on Ubuntu 18.04.

According to this answer, the solution is to remove all operational .yaml files: Ubuntu 17.10 disable netplan

I wouldn’t remove anything without backing up. We can do so easily by simply moving the files aside. First, locate the files:

sudo updatedb
locate netplan | grep yaml

On my 18.04 system, it appears that the only operational file is /etc/netplan/01-network-manager-all.yaml. Let’s move it:

mkdir ~/netplan
sudo mv /etc/netplan/01-network-manager-all.yaml /home/user/netplan

...where user is your user name.

Now check to make sure the file is truly gone:

ls /etc/netplan

Now make your additions to /etc/network/interfaces as required.

Reboot.

Any improvement?

Footnote: The exact process to do this is hard to find. We may need to refine a bit as we go.