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The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Key Applications and Application Protocols

Gopher Protocol (Gopher) 1 Telnet Protocol

When it comes to TCP/IP applications, file and message transfer applications such as electronic mail, FTP and the World Wide Web get the most attention, because they are the ones used most often on modern internetworks. Another category of TCP/IP application protocols that is less-well-known is the group that allows users to interactively access and use other computers directly over an internetwork, such as the public Internet. These applications are not often employed by end-users today but are still important—both from a historical perspective, and because of their usefulness in certain circumstances, especially to network administrators.

In this section, I provide a brief description of the “classical” interactive and remote application protocols used in TCP/IP. The first subsection describes the Telnet Protocol, one of the earliest and most important application protocols in TCP/IP, still used today both for remote device access and as the basis of communication of many other protocols. The second describes the Berkeley remote access family, often called the “r” commands or protocols because their command names begin with that letter. Finally, I provide a brief overview of the Internet Relay Chat (IRC) protocol, the original interactive chat application of the Internet and one still used widely today.

Gopher Protocol (Gopher) 1 Telnet Protocol