Ubuntu is actually installed in a Virtualbox virtual machine on Mac OS X Yosemite 10.10 (10.10.2). Before proceeding read the important intro below from  http://www.aircrack-ng.org/doku.php?id=cracking_wpa#introduction    Install aircrack-ng suite.     $ sudo apt-get install aircrack-ng     It should install and provide the following.      # dpkg -s aircrack-ng   Package: aircrack-ng   Status: install ok installed   Priority: optional   Section: net   Installed-Size: 2167   Maintainer: Ubuntu Developers   Architecture: amd64   Version: 1:1.1-6   Depends: libc6 (>= 2.15), libgcrypt11 (>= 1.4.5), libsqlite3-0 (>= 3.5.9), zlib1g (>= 1:1.1.4), wireless-tools, iw   Recommends: wget   Description: wireless WEP/WPA cracking utilities    aircrack-ng is an 802.11a/b/g WEP/WPA cracking program that can recover a    40-bit, 104-bit, 256-bit or 512-bit WEP key once enough encrypted packets    have been gathered. Also it can attack WPA1/2 networks with some advanced ...