Markup for https://aebian.org/story/change-back-ens-to-eth

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
allow-hotplug eth0
allow-hotplug eth1
iface eth0 inet dhcp
iface eth1 inet dhcp                                                                                                                                                       ~