Piggybacking is the act of following an authorized person through a secured door or electronically attacking to an authorized telecommunications link to intercept and possibly alter transmission and data. More precisely, this is gaining access to a restricted communications channel by using a session established by another user without the subscriber’s explicit permission or knowledge. Piggybacking can be defeated by logging out before walking away from a workstation or terminal or by initiating a screensaver that requires re-authentication when resuming.