As of 17.10, a new network configuration called netplan has been created. It looks more concise than the existing interface configuration (/etc/network/interfaces).

The files to change are as follows.

sudo vi /etc/netplan/50-cloud-init.yaml

Basically, when installed with dhcp, the following is displayed.

network:
    ethernets:
        enp4s0f2:
        addresses: []
            dhcp4: true
   version: 2

You can set the contents by entering ip and information as below.

network:
    ethernets:
        enp4s0f2:
            dhcp4: no
            addresses: [192.168.1.200/24]
            gateway4: 192.168.1.1
            nameservers:
                    addresses: [1.1.1.1,8.8.8.8,8.8.4.4]
    version: 2

And the changed contents are applied as below.

sudo netplan apply

You can check the changed contents with ifconfig.

$ifconfig
enp4s0f2: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
        inet 192.168.1.200 netmask 255.255.255.0 broadcast 192.168.1.255
        inet6 fe80::290:f5ff:fee7:6e10 prefixlen 64 scopeid 0x20<link>
        ether 00:90:f5:e7:6e:10 txqueuelen 1000 (Ethernet)
        RX packets 89208 bytes 132983451 (132.9 MB)
        RX errors 0 dropped 9 overruns 0 frame 0
        TX packets 55318 bytes 4234704 (4.2 MB)
        TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
        inet 127.0.0.1 netmask 255.0.0.0
        inet6 ::1 prefixlen 128 scopeid 0x10<host>
        loop txqueuelen 1000 (Local Loopback)
        RX packets 252 bytes 19812 (19.8 KB)
        RX errors 0 dropped 0 overruns 0 frame 0
        TX packets 252 bytes 19812 (19.8 KB)
        TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

By the way, dhcp4 is true, but when it is turned off, it is changed to no.

Everyone is using it like that… Hmm…

Strange but works well. -_-;;;