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TCP/IP Tutorial and Technical Overview - IBM Redbooks

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13.1 Telnet<br />

Telnet is a st<strong>and</strong>ard protocol with STD number 8. Its status is recommended. It is<br />

described in RFC 854 – Telnet Protocol Specifications <strong>and</strong> RFC 855 – Telnet<br />

Option Specifications.<br />

The Telnet protocol provides a st<strong>and</strong>ardized interface, through which a program<br />

on one host (the Telnet client) can access the resources of another host (the<br />

Telnet server) as though the client were a local terminal connected to the server.<br />

See Figure 13-1 for more details.<br />

For example, a user on a workstation on a LAN can connect to a host attached to<br />

the LAN as though the workstation were a terminal attached directly to the host.<br />

Of course, Telnet can be used across WANs as well as LANs.<br />

Figure 13-1 Telnet operation<br />

13.1.1 Telnet operation<br />

Most Telnet implementations do not provide you with graphics capabilities.<br />

Telnet protocol is based on three ideas:<br />

► The Network Virtual Terminal (NVT) concept. An NVT is an imaginary device<br />

with a basic structure common to a wide range of real terminals. Each host<br />

maps its own terminal characteristics to those of an NVT <strong>and</strong> assumes that<br />

every other host will do the same.<br />

484 <strong>TCP</strong>/<strong>IP</strong> <strong>Tutorial</strong> <strong>and</strong> <strong>Technical</strong> <strong>Overview</strong><br />

Workstation Terminal<br />

Remote<br />

Login<br />

LAN<br />

Host<br />

Local<br />

Login

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