I have not put in the rest of the code to make it change your mac address but here is a simple mac address generator.
Code
@ECHO OFF
setlocal
:loop
set /a n1=%random% %% 16
set /a n2=%random% %% 16
set /a n3=%random% %% 16
set /a n4=%random% %% 16
set /a n5=%random% %% 16
set /a n6=%random% %% 16
set /a n7=%random% %% 16
set /a n8=%random% %% 16
set /a n9=%random% %% 16
set /a n10=%random% %% 16
set /a n11=%random% %% 16
set /a n12=%random% %% 16
for %%a in ("10=a" "11=b" "12=c" "13=d" "14=e" "15=f") do (
call set n1=%%n1:%%~a%%
call set n2=%%n2:%%~a%%
call set n3=%%n3:%%~a%%
call set n4=%%n4:%%~a%%
call set n5=%%n5:%%~a%%
call set n6=%%n6:%%~a%%
call set n7=%%n7:%%~a%%
call set n8=%%n8:%%~a%%
call set n9=%%n9:%%~a%%
call set n10=%%n10:%%~a%%
call set n11=%%n11:%%~a%%
call set n12=%%n12:%%~a%%
)
if %n1%==%n2% goto loop
if %n3%==%n4% goto loop
if %n5%==%n6% goto loop
if %n7%==%n8% goto loop
if %n9%==%n10% goto loop
if %n11%==%n12% goto loop
CLS
echo %n1%%n2%%n3%%n4%%n5%%n6%%n7%%n8%%n9%%n10%%n11%%n12%
pause
goto loop