There are a lot of reasons you might want to manually set your MAC address for your network card. I won’t ask you what your reason is.

To change this setting, we’ll need to edit the /etc/network/interfaces file. You can choose to use a different editor if you’d like.

sudo gedit /etc/network/interfaces

You should see the line for your network interface, which is usually eth0. If you have dhcp enabled, it will look like this:

auto eth0
iface eth0 inet dhcp

Just add another line below it to make it look something like this:

auto eth0
iface eth0 inet dhcp
       hwaddress ether 01:02:03:04:05:06

Obviously you would want to choose something else for the MAC address, but it needs to be in the same format.

sudo /etc/init.d/networking restart

You will need to restart networking or reboot to take effect.