root@ubuntu:~# ls /sys/class/net/
enp0s3 enp0s8 lo
root@ubuntu:~# vim /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
source /etc/network/interfaces.d/*
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto enp0s3
iface enp0s3 inet dhcp
auto enp0s8
iface enp0s8 inet dhcp
root@ubuntu:~# /etc/init.d/networking restart
[ok] Restarting networking (via systectl):networking.service.