Bushel: Secure Your Apple ID With 2 Factor Authentication

Two-factor verification on your AppleID helps to keep everything nice and secure. Once enabled, you will need any two  of the following to access your iCloud account: The password to your Apple ID, a device trusted in the portal (we’ll trust devices during this process) or a recovery key (which we’ll create during this process). In other words, don’t loose your recovery key! Learn To Enable Two-Factor Verification to Secure your AppleID On The Bushel Blog

Mac OS X: 2 Factor Authentication

CryptoCARD can be used to provide 2 factor authentication.  This can easily be integrated into the VPN server for Mac OS X, although it will take a little while to get integrated into Open Directory.  However, it’s cost effective and available for OS X.