ifconfig is the go to command when you want to view anything related to your Internet or network connections on your Linux box. To view the details of the various network adaptors currently visible, simply run:

ifconfig

This will feed you back details about your available network adapters, MAC addresses, assigned IP, etc. Note the network adapter eth0. This is the default network adapter if you are connected via normal network cable.

Do release your currently assigned IP address, simply run:

sudo ifconfig eth0 down

This will shut down the eth0 interface and subsequently releases the IP in the process. To now renew your IP, run:

sudo ifconfig eth0 up

Done. If you re-run ifconfig you’ll see the new IP address. Useful if you want to release renew your IP without rebooting the whole machine!

Nifty.