In some situations you need to fake / change / spoof a MAC address of your network interface. macchanger Linux command does this job in no time. With this tool you can change your mac address of any Ethernet network device wired or wireless. Here is a small example:

My original mac address:

# ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:16:d3:23:7c:f7
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Memory:ee000000-ee020000

Turn off your network interface:

# ifconfig eth0 down

Use macchanger to randomly generate new MAC address and assign it to eth0 network interface:

# macchanger -r eth0
Current MAC: 00:16:d3:23:7c:f7 (unknown)
Faked MAC:   32:cf:cb:6c:63:cd (unknown)

In case you see a following error message:

ERROR: Can't change MAC: interface up or not permission: Cannot assign requested address

Make sure that your interface is down and you are running macchanger as a root user.
Enable eth0 network interface and check new MAC address:

# ifconfig eth0 up
# ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 32:cf:cb:6c:63:cd
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Memory:ee000000-ee020000

If for example a specific MAC address is required, use macchanger as follows:

# macchanger -m b2:aa:0e:56:ed:f7 eth0
Current MAC: 32:cf:cb:6c:63:cd (unknown)
Faked MAC:   b2:aa:0e:56:ed:f7 (unknown)

macchanger also allows you to change mac address for a specific network card vendor. Use a -l option to print a list of all know network card vendors.

macchanger is a linux-agnostic command thus it works the same across many Linux distributions. Here is an example on how to change mac address on Kali Linux.