NAME

telnet − user interface to the TELNET protocol

SYNOPSIS

telnet [ −v ] [ host_ [ port ] ]

DESCRIPTION

telnet communicates with another host using the TELNET protocol.  If telnet is invoked without arguments, it prompts for the host to which a connection is desired.  If it is invoked with arguments, it attempts to establish a connection to the host given on its command line.  In either case, if no port number is specified, telnet attempts to contact a TELNET server at the default port (port 23).  The host specification can be either a host name [see hosts(4)] or an Internet address (in “dot notation”). 

If the −v flag is given, all TELNET option negotiations are displayed.  Options sent by telnet are displayed as “SENT,” while options received from the TELNET server are displayed as “RCVD.”

Once a connection is established, telnet enters input mode.  In this mode, typed text is sent to the remote host.  This can be done in one of two ways, at the remote host’s discretion.  If the remote host volunteers to perform character echo, each character typed is sent to the remote host uninspected.  Otherwise, local line editing is performed and data are not sent until a complete line has been entered.  In either case, the line is terminated with the standard TELNET end-of-line sequence <cr><lf> when it is sent.  Similarly, in this mode incoming data are assumed to be in chunks of lines and the <cr><lf> sequence is translated into the local end-of-line marker. 

Once a connection has been established, telnet enters command mode when the telnet escape character is typed.  Initially, this character is ’^]’, but the user can change the escape character, as described below.  In command mode, telnet accepts and executes the commands listed below.  These commands are processed locally and are not seen by the remote host.  Only enough characters to uniquely identify the command need be typed. 

escape [escape-char]
Set the telnet escape character.  Single character control characters can be used, for example “control-X” is “^X”. 

quit Close any open TELNET session and exit telnet. 

status
Show the current status of telnet.  This includes the peer and debugging state and the current escape character. 

? [command]
Get help.  With no arguments, telnet prints a help summary.  If a command is specified, telnet prints the available information on it. 

BUGS

The process structure used by TELNET reflects a fundamental limitation of many versions of UNIX.  This severely restricts the number and kind of TELNET options that can be supported. 

Version 2.4  —  September 29, 2021