Tonight, I replaced one of my network interfaces in my computer. I changed the old one, which is Fast Ethernet type, with the new one, which is Gigabit type. I was working in my Ubuntu server 11.04. When I finished replacing the interface. I turned my computer on to see will it work. I found that the new interface didn”t work. When I plugged the cable in, the LED indicator simply didn”t light.

After that I tried to see whether the problem is within the device or the Operating System. I run

user@ubuntu:~$ ifconfig

and I got the list of my interfaces, but the new one wasn”t there (I knew because the total of my interfaces decreased) then I knew the problem lies within the Operating System. After spending a few minute searching for the answer using Google finally I found it here.

We can re-enable our interfaces by deleting one file.

user@ubuntu:~$ sudo rm /etc/udev/rules.d/70-persistent-net.rules/

After that, just reboot the computer and all will work well as expected.