Network access control (NAC) is saving the University of North Carolina at Chapel Hill $40,000 per year by keeping students from illegally using peer-to-peer file-sharing apps. The program is called Hall Pass, and has reduced complaints that the networking staff has to deal with. Last spring, the school implemented a pop-up that simply warned students that the apps had been detected. There was no threat of being kicked off the network or disciplinary action. Even so, about 30% of students who were warned removed the applications anyway.”]