Null Modem

A null modem directly connects two devices using a RS-232 serial cable. It is widely used for transferring files between computers or remote operations. In the Microsoft Windows operating system, the direct cable connection may be used over a null modem connection. Later versions of MS-DOS came included with the InterLnk software as an alternative to the process. It allowed the mapping of a hard drive on one computer to act as a network drive on another computer. This required no modem or internal hardware such as a network card. The growing popularity and availability of faster data exchange systems such as Ethernet connections, have made the use of null modems far less common. On the other hand, a null cable modem can still be rather useful to kernel hackers. This is because it allows a user to debug a system with minimum codes and device drivers. A hacker can use this exploit to cause a user’s keyboard and monitor to become unusable.