ifconfig does not recognize eth0, only wlan0 and lo (Ubuntu 14.04, Macbrook Pro) [duplicate]
Solution 1:
Check whether your interface has the name eth0 by typing ifconfig -a.
Probably it is named something like p1p1 now. If it is and you want it to be eth0, add biosdevname=0 to the boot options in your /etc/default/grub.