Change the mac address of a device (useful for various spoofing, e.g. for extending limited access on public wifi networks). Tested in OSX

change_mac_address.bash

#!/bin/bash

# Author: Stein Fletcher <steinfletcher@gmail.com>
# Purpose: Changes the mac address for the en0 device

# get the current mac address
old_addr=`/sbin/ifconfig en0 | awk '/ether/ {print $2}'`

# Generates a random new mac address using openssl
new_addr=`openssl rand -hex 6 | sed 's/\(..\)/\1:/g; s/.$//'`

# change the actual address
sudo /sbin/ifconfig en0 ether $new_addr

timestamp=`date`
echo "$timestamp: Changed mac address from $old_addr to $new_addr"