Tested on Ubuntu 16
From Ubuntu 15, network interfaces names are generated by systemd/udev using predictable names based in several policies and schemes like firmware, BIOS, interface’s MAC address, geographical location and others. Names like enp2s0 for example.
However it’s possible change the name, if you want retro-compatibility with old software or for scripting, to do it add net.ifnames=0 to the /etc/default/grub file:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash net.ifnames=0"
Now make an update-grub:
~ $ sudo update-grub
~ $ sudo reboot
Interfaces now be called eth0, wlan0, eth1 etc…