

TELNET(1)                 Minix Programmer's Manual                  TELNET(1)


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 character"
     (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)).


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     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
          permission 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.





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     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 characters (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


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          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 character
          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.




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     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 system 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 descriptions 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.





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TELNET(1)                 Minix Programmer's Manual                  TELNET(1)


     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.











































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