My ethernet controller is eth0 and has MAC address (or Hardware Address) is 00:0f:1f:f7:b1:64 . I know that there are no MACs with HWaddr 00:0f:1f:f7:b1:65 on the network. Let's change that MAC address.
# ifconfig eth0 down # ifconfig eth0 hw ether 00:0f:1f:f7:b1:65 # ifconfig eth0 upTake that! Now, you can very very easily have a little tee script and substitute away every time you're disallowed. But, come on, what tomfoolery are you up to that'd make you programatically denied network access?