TELNET(1C)																TELNET(1C)

NAME

       telnet - user interface to the TELNET protocol

SYNOPSIS

       telnet [ host [ port ] ]

DESCRIPTION

       Telnet is used to communicate with another host using the TELNET protocol.  If telnet is invoked without arguments, it enters command mode,
       indicated by its prompt ("telnet>").  In this mode, it accepts and executes the commands listed below.  If it is invoked with arguments, it
       performs an open command (see below) with those arguments.

       Once  a	connection  has been opened, telnet enters an input mode.  The input mode entered will be either "character at a time" or "line by
       line" depending on what the remote system supports.

       In "character at a time" mode, most text typed is immediately sent to the remote host for processing.

       In "line by line" mode, all text is echoed locally, and (normally) only completed lines are sent to the remote host.  The "local echo char-
       acter"  (initially  "^E")  may be used to turn off and on the local echo (this would mostly be used to enter passwords without the password
       being echoed).

       In either mode, if the localchars toggle is TRUE (the default in line mode; see below), the user's quit, intr,  and  flush  characters  are
       trapped	locally,  and  sent as TELNET protocol sequences to the remote side.  There are options (see toggle autoflush and toggle autosynch
       below) which cause this action to flush subsequent output to the terminal (until the remote host  acknowledges  the  TELNET  sequence)  and
       flush previous terminal input (in the case of quit and intr).

       While  connected  to  a	remote host, telnet command mode may be entered by typing the telnet "escape character" (initially "^]").  When in
       command mode, the normal terminal editing conventions are available.

       COMMANDS

       The following commands are available.  Only enough of each command to uniquely identify it need be typed (this is also true  for  arguments
       to the mode, set, toggle, and display commands).

       open host [ port ]
	      Open  a connection to the named host.  If no port number is specified, telnet will attempt to contact a TELNET server at the default
	      port.  The host specification may be either a host name (see hosts(5)) or an Internet address specified in the "dot  notation"  (see
	      inet(3N)).

       close
	      Close a TELNET session and return to command mode.

       quit
	      Close any open TELNET session and exit telnet.  An end of file (in command mode) will also close a session and exit.

       z
	      Suspend telnet.  This command only works when the user is using the csh(1).

       mode type
	      Type  is	either line (for "line by line" mode) or character (for "character at a time" mode).  The remote host is asked for permis-
	      sion to go into the requested mode.  If the remote host is capable of entering that mode, the requested mode will be entered.

       status
	      Show the current status of telnet.  This includes the peer one is connected to, as well as the current mode.

       display [ argument... ]
	      Displays all, or some, of the set and toggle values (see below).

       ? [ command ]
	      Get help.  With no arguments, telnet prints a help summary.  If a command is specified, telnet will print the help  information  for
	      just that command.

       send arguments
	      Sends one or more special character sequences to the remote host.  The following are the arguments which may be specified (more than
	      one argument may be specified at a time):

	      escape
		     Sends the current telnet escape character (initially "^]").

	      synch
		     Sends the TELNET SYNCH sequence.  This sequence causes the remote system to discard all previously typed (but not	yet  read)
		     input.   This sequence is sent as TCP urgent data (and may not work if the remote system is a 4.2 BSD system -- if it doesn't
		     work, a lower case "r" may be echoed on the terminal).

	      brk
		     Sends the TELNET BRK (Break) sequence, which may have significance to the remote system.

	      ip
		     Sends the TELNET IP (Interrupt Process) sequence, which should cause  the	remote	system	to  abort  the	currently  running
		     process.

	      ao
		     Sends  the TELNET AO (Abort Output) sequence, which should cause the remote system to flush all output from the remote system
		     to the user's terminal.

	      ayt
		     Sends the TELNET AYT (Are You There) sequence, to which the remote system may or may not choose to respond.

	      ec
		     Sends the TELNET EC (Erase Character) sequence, which should cause the remote system to erase the last character entered.

	      el
		     Sends the TELNET EL (Erase Line) sequence, which should cause the remote system to erase the line currently being entered.

	      ga
		     Sends the TELNET GA (Go Ahead) sequence, which likely has no significance to the remote system.

	      nop
		     Sends the TELNET NOP (No OPeration) sequence.

	      ?
		     Prints out help information for the send command.

       set argument value
	      Set any one of a number of telnet variables to a specific value.	The special value "off" turns off the function associated with the
	      variable.  The values of variables may be interrogated with the display command.	The variables which may be specified are:

	      echo
		     This is the value (initially "^E") which, when in "line by line" mode, toggles between doing local echoing of entered charac-
		     ters (for normal processing), and suppressing echoing of entered characters (for entering, say, a password).

	      escape
		     This is the telnet escape character (initially "^[") which causes entry into telnet command mode (when connected to a  remote
		     system).

	      interrupt
		     If telnet is in localchars mode (see toggle localchars below) and the interrupt character is typed, a TELNET IP sequence (see
		     send ip above) is sent to the remote host.  The initial value for the interrupt character is taken to be the terminal's  intr
		     character.

	      quit
		     If  telnet  is  in  localchars mode (see toggle localchars below) and the quit character is typed, a TELNET BRK sequence (see
		     send brk above) is sent to the remote host.  The initial value for the quit character is taken  to  be  the  terminal's  quit
		     character.

	      flushoutput
		     If  telnet  is  in localchars mode (see toggle localchars below) and the flushoutput character is typed, a TELNET AO sequence
		     (see send ao above) is sent to the remote host.  The initial value for the flush character is  taken  to  be  the	terminal's
		     flush character.

	      erase
		     If telnet is in localchars mode (see toggle localchars below), and if telnet is operating in "character at a time" mode, then
		     when this character is typed, a TELNET EC sequence (see send ec above) is sent to the remote system.  The initial	value  for
		     the erase character is taken to be the terminal's erase character.

	      kill
		     If telnet is in localchars mode (see toggle localchars below), and if telnet is operating in "character at a time" mode, then
		     when this character is typed, a TELNET EL sequence (see send el above) is sent to the remote system.  The initial	value  for
		     the kill character is taken to be the terminal's kill character.

	      eof
		     If telnet is operating in "line by line" mode, entering this character as the first character on a line will cause this char-
		     acter to be sent to the remote system.  The initial value of the eof character is taken to be the terminal's eof character.

       toggle arguments...
	      Toggle (between TRUE and FALSE) various flags that control how telnet responds to events.  More than one argument may be	specified.
	      The state of these flags may be interrogated with the display command.  Valid arguments are:

	      localchars
		     If  this  is  TRUE,  then	the flush, interrupt, quit, erase, and kill characters (see set above) are recognized locally, and
		     transformed into (hopefully) appropriate TELNET control sequences (respectively ao, ip, brk, ec, and  el;	see  send  above).
		     The initial value for this toggle is TRUE in "line by line" mode, and FALSE in "character at a time" mode.

	      autoflush
		     If  autoflush  and  localchars are both TRUE, then when the ao, intr, or quit characters are recognized (and transformed into
		     TELNET sequences; see set above for details), telnet refuses to display any data on the user's terminal until the remote sys-
		     tem  acknowledges (via a TELNET Timing Mark option) that it has processed those TELNET sequences.	The initial value for this
		     toggle is TRUE if the terminal user had not done an "stty noflsh", otherwise FALSE (see stty(1)).

	      autosynch
		     If autosynch and localchars are both TRUE, then when either the intr or quit characters is typed (see set above for  descrip-
		     tions  of	the  intr and quit characters), the resulting TELNET sequence sent is followed by the TELNET SYNCH sequence.  This
		     procedure should cause the remote system to begin throwing away all previously typed input until both of the TELNET sequences
		     have been read and acted upon.  The initial value of this toggle is FALSE.

	      crmod
		     Toggle  carriage  return mode.  When this mode is enabled, most carriage return characters received from the remote host will
		     be mapped into a carriage return followed by a line feed.	This mode does not affect those characters typed by the user, only
		     those  received  from  the  remote host.  This mode is not very useful unless the remote host only sends carriage return, but
		     never line feed.  The initial value for this toggle is FALSE.

	      debug
		     Toggles socket level debugging (useful only to the superuser).  The initial value for this toggle is FALSE.

	      options
		     Toggles the display of some internal telnet protocol processing (having to do with TELNET options).  The  initial	value  for
		     this toggle is FALSE.

	      netdata
		     Toggles the display of all network data (in hexadecimal format).  The initial value for this toggle is FALSE.

	      ?
		     Displays the legal toggle commands.

BUGS

       There is no adequate way for dealing with flow control.

       On some remote systems, echo has to be turned off manually when in "line by line" mode.

       There is enough settable state to justify a .telnetrc file.

       No capability for a .telnetrc file is provided.

       In "line by line" mode, the terminal's eof character is only recognized (and sent to the remote system) when it is the first character on a
       line.

4.2 Berkeley Distribution					   May 10, 1986 							TELNET(1C)