Ethernet interface eth0 not detected in Ubuntu 12.04
Check that the led's flicker when you plugin the Ethernet cable, if not check in your bios and enable Ethernet there.
Here is what I had to do to make it work.
Run the following command in your terminal.
You should see the following in the list of devices to confirm this is the Ethernet interface you have.
Ethernet controller: Atheros Communications Inc. AR8161 Gigabit Ethernet (rev 10)
Then install the driver from Ubuntu
Don't get the drivers released after 2012-05-10 it will not work
wget -O- http://linuxwireless.org/download/compat-wireless-2.6/compat-wireless-2012-05-09-p.tar.bz2 | tar -xj cd compat-wireless-2012-05-09-p
sudo Make install
Then load the new driver module.
If your network cable is connected with your router on DHCP.
sudo modprobe alx
run ifconfig and you should see your interface eth0
ifconfig to see your new ethernet ports.
and it should work now.