Abstract: A security system for preventing access to a computer by an unauthorized remote user is disclosed. A plurality of information transmission paths, such as telephone lines, are connected to a security computer. If a remote user provides an authorized access code to the security computer over one of the telephone lines, the line is connected through a switch unit to the main computer. If an unauthorized access code is provided the security computer, a signal is generated to the switch unit to disconnect all of the telephone lines from the main computer. A counter is connected to the telephone lines which generates a disconnect signal to the switch unit when the number of remote users utilizing or attempting to gain access to the main computer exceeds a predetermined maximum number. The security computer and the counter can also be connected to an alarm unit for generating an alarm indication that an unauthorized user has attempted to gain access to the main computer.