Randomize MAC address (e.g. unlimited wifi access on airports)

mac-randomize.sh

#!/bin/bash
set -e

current_mac() {
  ifconfig en0 ether | awk '/ether / { print $2 }'
}

current_mac_wifi() {
  networksetup -getmacaddress Wi-Fi | awk '{ print $3 }'
}

random_mac() {
  openssl rand -hex 6 | sed "s/\(..\)/\1:/g; s/:$//"
}

assign_mac() {
  sudo ifconfig en0 ether "$1"
}

randomize() {
  old_mac="$(current_mac)"
  echo "previous MAC address: ${old_mac}"

  # The first byte of a host MAC address must be even
  while [ "$old_mac" = "$(current_mac)" ]; do
    assign_mac "$(random_mac)"
    sleep 0.1
  done

  echo "new MAC address: $(current_mac)"
}

networksetup -setairportpower en0 on
sudo /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -z

if [ -n "$1" ]; then
  assign_mac "$1"
  echo "new MAC address: $(current_mac)"
else
  randomize
fi

sudo networksetup -detectnewhardware
echo "Wi-Fi MAC address: $(current_mac_wifi)"