Lan not working if cable not inside while booting

Question

I have an annoying problem. Every time the LAN cable is not in while booting, I cannot get any connection to the internet, network, router, etc. I tried to plug in and out the cable several times - but nothing happened, besides that I always shows that LAN is disconnected. The same happens after sleeping mode.

I am new to Ubuntu (12.04) and hoping for a hint!

Thanks in advance!

Answer 1

DHCP protocol can not assign your NIC an IP address without a cable connected. Obtain root acces in a console and execute dhclient eth0 where eth0 is the name of your NIC.

Answer 2

Try opening a terminal and use this command:

sudo /etc/init.d/networking restart

if this does not work, try stopping and starting the connection:

sudo /etc/init.d/networking stop
sudo /etc/init.d/networking start