ubuntu從17.10開始，已放棄在/etc/network/interfaces里固定IP的配置，而是改成netplan方式了

配置如下：

network:
    ethernets:
        enp4s0:
            addresses: [192.168.0.20/24]  //IP址
            gateway4: 192.168.0.1  // 網(wǎng)關(guān)
            nameservers:
             addresses: [114.114.114.114, 192.168.0.1] //DNS
            dhcp4: no
            optional: no
    version: 2

啟用生效

sudo netplan apply