import random
import os
import subprocess 

def get_rand():
    return random.choice("abcdef0123456789") 

def new_mac():
    new_ = "" 
    for i in range(0,5):
        new_ += get_rand() + get_rand() + ":"  
    new_ += get_rand() + get_rand() 
    return new_

print(os.system("ifconfig eth0 | grep ether | grep -oE [0-9abcdef:]{17}")) 
subprocess.call(["sudo","ifconfig","eth0","down"]) 
new_m = new_mac() 
subprocess.call(["sudo","ifconfig","eth0","hw","ether","%s"%new_m]) 
subprocess.call(["sudo","ifconfig","eth0","up"]) 
print(os.system("ifconfig eth0 | grep ether | grep -oE [0-9abcdef:]{17}"))