You are responsible for network security at a defense contractor. You are very concerned about sensitive data not getting out of your network. You have specific concerns about employees or contractors sending out files via FTP, or even spyware sending out data. You have blocked and monitored ports (as many as you can) on your firewall, and of course, run an anti spyware package.

Which of the following is another step you should take in preventing sensitive data from being sent out of your network without authorization?