Configure network in Ubuntu 18

The network configuration has changed in Ubuntu 18 from all the previous versions. The new version uses Netplan and it is somewhat harder if you don't know yaml. The discussion for pros and cons of this move by Ubuntu can be infinite (why change what's working; this is a tool, I don't want to learn the new ways, etc.), but this is a quick tutorial for quickly changing the IP address. (There's lot of information on Netplan and various things one can do with it)

The network configuration files are located in /etc/netplan. Configuration file can be opened as below:

vim /etc/netplan/50-cloud-init.yaml

With comments removed, this is the configuration data for a simple DHCP setup:

network:
 ethernets:
   enp0s3:
     dhcp4: true
 version: 2

If you would like to setup a static IP, these are the options to use:

network:
 ethernets:
    enp0s3:
        addresses: [172.16.0.15/24]
        gateway4: 172.16.0.1
        dhcp4: no
        nameservers:
             addresses: [172.16.0.1,8.8.8.8]
        optional: true
 version: 2

In the above example:

IP address: 172.16.0.15

Gateway: 172.16.0.1

DNS: 172.16.0.1, 8.8.8.8

No network or broadcast address needed. Subnet address is specified in the IP itself (ie: 172.16.0.15/24)

Reboot the server or restart the network by applying the configuration:

netplan apply

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