For various reasons you might want to manually change your MAC address for your network card.

There’s an easy way that you just need to edit /etc/network/interfaces file on your ubuntu.

Run following command in terminal

sudo gedit /etc/network/interfaces

File will be opened up,add this line at the end.Close and save it.

hwaddress ether 01:02:03:04:05:06

Change the address to what you want,the random number is hex.

At last restart networking:

sudo /etc/init.d/networking restart