Telnet
Telnet is a simple Internet program for connecting users to remote hosts (computer systems accessible at distant locations) and servers (network devices that manage network resources). The Telnet program contains a set of procedures (commonly called a "protocol") that enables an Internet user to log on to and enter commands on a distant (remote) computer in order to simulate a user who is directly attached to the computer. Telnet, sometimes abbreviated TN, is one of the oldest activities on the Internet, being used primarily to access online databases and to read articles stored on university servers.
Telnet uses terminal emulation, a program that allows personal computers (PCs) to respond like a mainframe terminal that is connected to, and able to access, a mainframe computer or bulletin board service. (A mainframe terminal is a device consisting of a combination of keyboard and display screen that allows a user to communicate with a mainframe computer. When a user uses a personal computer in terminal emulation mode the mainframe interacts with the PC as it would with any mainframe terminal.) Transmission Control Protocol/Internet Protocol (TCP/IP), a suite of communications protocols used to connect hosts on the Internet, supports Telnet. TCP/IP is built into the UNIX operating system that is used by the Internet as a standard format for transmitting data over networks. Users enter text-based commands through the Telnet program and the commands are executed as if they were directly being entered through the server console. This enables the Telnet user to remotely manipulate the server and communicate with other servers on the network. Generally the user must possess a valid user identification (ID) and password for the remote computer. Features generally included with Telnet are electronic mail (e-mail), program downloads, and "chatrooms" with other Telnet users. Many computer systems, like those associated with libraries, allow Telnet users to access their large databases in order to perform searches and other needed activities.
It is also possible to activate Telnet within a Web browser by changing the http:// to telnet:// and entering the site's address. Normally a login prompt will appear to allow the user to enter that site; that is, if the correct login identification is provided. A better way to enter a Telnet site is to download a Telnet program onto a computer, open an Options menu on the computer's Web browser, and add it as a "helper" application or as an external "viewer." Most commercial online services do not allow users to use Telnet, but there are a few workarounds. For example, the Spry Mosaic browser that is included with the CompuServe Internet package works just like Netscape, so a Telnet helper program can be added.
Telnet originated before the Internet. However, it has been generally overshadowed by the more comprehensive and easier to use Internet so that it is now merely a component of the Internet. Today users are able to connect to web sites and other peoples' computers with other programs besides Telnet. Telnet's main advantage is that it allows users to log on to a remote system and run programs on that system just as if it were an actual connected mainframe terminal. But the main disadvantage of Telnet is that the actions available are very limited. For instance, files cannot be saved.
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