function remac() {
  local progress='.oO°Oo'
  local airport=/System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/airport
  local ssid=$($airport -I|awk '/^ *SSID/ {print $2}')
  local iface=$(networksetup -listallhardwareports|grep -A1 Wi-Fi|awk '/Device:/ {print $2}')
  local mac=${1:-00$(openssl rand -hex 5|sed 's/\(..\)/:\1/g')}

  echo Disconnecting Wi-Fi $iface from SSID $ssid to set new mac address $mac...
  sudo $airport -z
  local i n=0
  until ifconfig $iface ether | grep -q $mac ; do
    sudo ifconfig $iface ether $mac
    sleep .1
    i=$[++n % $#progress + 1]
    echo -n "$progress[$i]\r"
  done

  networksetup -setairportnetwork $iface $ssid \
  && echo mac is $mac \
  || echo failed $mac && false
}