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telnet - user interface to the TELNET protocol

 

NAME

      telnet - user interface to the TELNET protocol
 

SYNOPSIS

      telnet [-468EFKLNacdfrux] [-S tos] [-X authtype] [-e escapechar]
             [-k realm] [-l user] [-n tracefile] [-s src_addr] [host [port]]
 

DESCRIPTION

      The telnet command is used to communicate with another host using the
      TELNET protocol.  If telnet is invoked without the host argument, 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 with those arguments.
 
      Options:
 
      -4      Forces telnet to use IPv4 addresses only.
 
      -6      Forces telnet to use IPv6 addresses only.
 
      -8      Specifies an 8-bit data path.  This causes an attempt to negoti‐
              ate the TELNET BINARY option on both input and output.
 
      -E      Stops any character from being recognized as an escape character.
 
      -F      If Kerberos V5 authentication is being used, the -F option allows
              the local credentials to be forwarded to the remote system,
              including any credentials that have already been forwarded into
              the local environment.
 
      -K      Specifies no automatic login to the remote system.
 
      -L      Specifies an 8-bit data path on output.  This causes the BINARY
              option to be negotiated on output.
 
      -N      Prevents IP address to name lookup when destination host is given
              as an IP address.
 
      -S tos  Sets the IP type-of-service (TOS) option for the telnet connec‐
              tion to the value tos, which can be a numeric TOS value or, on
              systems that support it, a symbolic TOS name found in the
              /etc/iptos file.
 
      -X atype
              Disables the atype type of authentication.
 
      -a      Attempt automatic login.  Currently, this sends the user name via
              the USER variable of the ENVIRON option if supported by the
              remote system.  The name used is that of the current user as
              returned by getlogin(2) if it agrees with the current user ID,
              otherwise it is the name associated with the user ID.
 
      -c      Disables the reading of the user’s .telnetrc file.  (See the
              toggle skiprc command on this man page.)
 
      -d      Sets the initial value of the debug toggle to TRUE.
 
      -e escapechar
              Sets the initial telnet escape character to escapechar.  If
              escapechar is omitted, then there will be no escape character.
 
      -f      If Kerberos V5 authentication is being used, the -f option allows
              the local credentials to be forwarded to the remote system.
 
      -k realm
              If Kerberos authentication is being used, the -k option requests
              that telnet obtain tickets for the remote host in realm realm
              instead of the remote host’s realm, as determined by
              krb_realmofhost(3).
 
      -l user
              When connecting to the remote system, if the remote system under‐
              stands the ENVIRON option, then user will be sent to the remote
              system as the value for the variable USER.  This option implies
              the -a option.  This option may also be used with the open com‐
              mand.
 
      -n tracefile
              Opens tracefile for recording trace information.  See the set
              tracefile command below.
 
      -r      Specifies a user interface similar to rlogin(1).  In this mode,
              the escape character is set to the tilde (~) character, unless
              modified by the -e option.
 
      -s src_addr
              Set the source IP address for the telnet connection to src_addr,
              which can be an IP address or a host name.
 
      -u      Forces telnet to use AF_UNIX addresses only (e.g., UNIX domain
              sockets, accessed with a file path).
 
      -x      Turns on encryption of the data stream if possible.
 
      host    Indicates the official name, an alias, or the Internet address of
              a remote host.  If host starts with a ‘/’, telnet establishes a
              connection to the corresponding named socket.
 
      port    Indicates a port number (address of an application).  If a number
              is not specified, the default telnet port is used.
 
      When in rlogin mode, a line of the form ~.  disconnects from the remote
      host; ~ is the telnet escape character.  Similarly, the line ~^Z suspends
      the telnet session.  The line ~^] escapes to the normal telnet escape
      prompt.
 
      Once a connection has been opened, telnet will attempt to enable the
      TELNET LINEMODE option.  If this fails, then telnet will revert to one of
      two input modes: either “character at a time” or “old line by line”
      depending on what the remote system supports.
 
      When LINEMODE is enabled, character processing is done on the local sys‐
      tem, under the control of the remote system.  When input editing or char‐
      acter echoing is to be disabled, the remote system will relay that infor‐
      mation.  The remote system will also relay changes to any special charac‐
      ters that happen on the remote system, so that they can take effect on
      the local system.
 
      In “character at a time” mode, most text typed is immediately sent to the
      remote host for processing.
 
      In “old 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).
 
      If the LINEMODE option is enabled, or if the localchars toggle is TRUE
      (the default for “old line by line”; see below), the user’s quit, intr,
      and flush characters are trapped locally, and sent as TELNET protocol
      sequences to the remote side.  If LINEMODE has ever been enabled, then
      the user’s susp and eof are also sent as TELNET protocol sequences, and
      quit is sent as a TELNET ABORT instead of BREAK.  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 acknowl‐
      edges 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.
 
      The following telnet 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, unset, slc, environ, and display commands).
 
      auth argument ...
                 The auth command manipulates the information sent through the
                 TELNET AUTHENTICATE option.  Valid arguments for the auth com‐
                 mand are:
 
                 disable type  Disables the specified type of authentication.
                               To obtain a list of available types, use the
                               auth disable ? command.
 
                 enable type   Enables the specified type of authentication.
                               To obtain a list of available types, use the
                               auth enable ? command.
 
                 status        Lists the current status of the various types of
                               authentication.
 
      close      Close a TELNET session and return to command mode.
 
      display argument ...
                 Displays all, or some, of the set and toggle values (see
                 below).
 
      encrypt argument ...
                 The encrypt command manipulates the information sent through
                 the TELNET ENCRYPT option.
 
                 Valid arguments for the encrypt command are:
 
                 disable type [input | output]
                               Disables the specified type of encryption.  If
                               you omit the input and output, both input and
                               output are disabled.  To obtain a list of avail‐
                               able types, use the encrypt disable ? command.
 
                 enable type [input | output]
                               Enables the specified type of encryption.  If
                               you omit input and output, both input and output
                               are enabled.  To obtain a list of available
                               types, use the encrypt enable ? command.
 
                 input         This is the same as the encrypt start input com‐
                               mand.
 
                 -input        This is the same as the encrypt stop input com‐
                               mand.
 
                 output        This is the same as the encrypt start output
                               command.
 
                 -output       This is the same as the encrypt stop output com‐
                               mand.
 
                 start [input | output]
                               Attempts to start encryption.  If you omit input
                               and output, both input and output are enabled.
                               To obtain a list of available types, use the
                               encrypt enable ? command.
 
                 status        Lists the current status of encryption.
 
                 stop [input | output]
                               Stops encryption.  If you omit input and output,
                               encryption is on both input and output.
 
                 type type     Sets the default type of encryption to be used
                               with later encrypt start or encrypt stop com‐
                               mands.
 
      environ arguments ...
                 The environ command is used to manipulate the variables that
                 may be sent through the TELNET ENVIRON option.  The initial
                 set of variables is taken from the users environment, with
                 only the DISPLAY and PRINTER variables being exported by
                 default.  The USER variable is also exported if the -a or -l
                 options are used.
 
                 Valid arguments for the environ command are:
 
                 define variable value
                             Define the variable variable to have a value of
                             value.  Any variables defined by this command are
                             automatically exported.  The value may be enclosed
                             in single or double quotes so that tabs and spaces
                             may be included.
 
                 undefine variable
                             Remove variable from the list of environment vari‐
                             ables.
 
                 export variable
                             Mark the variable variable to be exported to the
                             remote side.
 
                 unexport variable
                             Mark the variable variable to not be exported
                             unless explicitly asked for by the remote side.
 
                 list        List the current set of environment variables.
                             Those marked with a * will be sent automatically,
                             other variables will only be sent if explicitly
                             requested.
 
                 ?           Prints out help information for the environ com‐
                             mand.
 
      logout     Sends the TELNET LOGOUT option to the remote side.  This com‐
                 mand is similar to a close command; however, if the remote
                 side does not support the LOGOUT option, nothing happens.  If,
                 however, the remote side does support the LOGOUT option, this
                 command should cause the remote side to close the TELNET con‐
                 nection.  If the remote side also supports the concept of sus‐
                 pending a user’s session for later reattachment, the logout
                 argument indicates that you should terminate the session imme‐
                 diately.
 
      mode type  Type is one of several options, depending on the state of the
                 TELNET session.  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.
 
                 character     Disable the TELNET LINEMODE option, or, if the
                               remote side does not understand the LINEMODE
                               option, then enter “character at a time” mode.
 
                 line          Enable the TELNET LINEMODE option, or, if the
                               remote side does not understand the LINEMODE
                               option, then attempt to enter “old-line-by-line”
                               mode.
 
                 isig (-isig)  Attempt to enable (disable) the TRAPSIG mode of
                               the LINEMODE option.  This requires that the
                               LINEMODE option be enabled.
 
                 edit (-edit)  Attempt to enable (disable) the EDIT mode of the
                               LINEMODE option.  This requires that the
                               LINEMODE option be enabled.
 
                 softtabs (-softtabs)
                               Attempt to enable (disable) the SOFT_TAB mode of
                               the LINEMODE option.  This requires that the
                               LINEMODE option be enabled.
 
                 litecho (-litecho)
                               Attempt to enable (disable) the LIT_ECHO mode of
                               the LINEMODE option.  This requires that the
                               LINEMODE option be enabled.
 
                 ?             Prints out help information for the mode com‐
                               mand.
 
      open host [-l user] [[-]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)), an Internet address specified in the “dot
                 notation” (see inet(3)), or IPv6 host name or IPv6 coloned-
                 hexadecimal address.  The -l option may be used to specify the
                 user name to be passed to the remote system via the ENVIRON
                 option.  When connecting to a non-standard port, telnet omits
                 any automatic initiation of TELNET options.  When the port
                 number is preceded by a minus sign, the initial option negoti‐
                 ation is done.  After establishing a connection, the file
                 .telnetrc in the users home directory is opened.  Lines begin‐
                 ning with a # are comment lines.  Blank lines are ignored.
                 Lines that begin without white space are the start of a
                 machine entry.  The first thing on the line is the name of the
                 machine that is being connected to.  The rest of the line, and
                 successive lines that begin with white space are assumed to be
                 telnet commands and are processed as if they had been typed in
                 manually to the telnet command prompt.
 
      quit       Close any open TELNET session and exit telnet.  An end of file
                 (in command mode) will also close a session and exit.
 
      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):
 
                 abort   Sends the TELNET ABORT (Abort processes) sequence.
 
                 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.
 
                 brk     Sends the TELNET BRK (Break) sequence, which may have
                         significance to the remote system.
 
                 ec      Sends the TELNET EC (Erase Character) sequence, which
                         should cause the remote system to erase the last char‐
                         acter entered.
 
                 el      Sends the TELNET EL (Erase Line) sequence, which
                         should cause the remote system to erase the line cur‐
                         rently being entered.
 
                 eof     Sends the TELNET EOF (End Of File) sequence.
 
                 eor     Sends the TELNET EOR (End of Record) sequence.
 
                 escape  Sends the current telnet escape character (initially
                         “^”).
 
                 ga      Sends the TELNET GA (Go Ahead) sequence, which likely
                         has no significance to the remote system.
 
                 getstatus
                         If the remote side supports the TELNET STATUS command,
                         getstatus will send the subnegotiation to request that
                         the server send its current option status.
 
                 ip      Sends the TELNET IP (Interrupt Process) sequence,
                         which should cause the remote system to abort the cur‐
                         rently running process.
 
                 nop     Sends the TELNET NOP (No OPeration) sequence.
 
                 susp    Sends the TELNET SUSP (SUSPend process) sequence.
 
                 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 4.2BSD system -- if it doesn’t work, a lower case
                         “r” may be echoed on the terminal).
 
                 do cmd
 
                 dont cmd
 
                 will cmd
 
                 wont cmd
                         Sends the TELNET DO cmd sequence.  Cmd can be either a
                         decimal number between 0 and 255, or a symbolic name
                         for a specific TELNET command.  Cmd can also be either
                         help or ? to print out help information, including a
                         list of known symbolic names.
 
                 ?       Prints out help information for the send command.
 
      set argument value
 
      unset argument value
                 The set command will set any one of a number of telnet vari‐
                 ables to a specific value or to TRUE.  The special value off
                 turns off the function associated with the variable, this is
                 equivalent to using the unset command.  The unset command will
                 disable or set to FALSE any of the specified functions.  The
                 values of variables may be interrogated with the display com‐
                 mand.  The variables which may be set or unset, but not tog‐
                 gled, are listed here.  In addition, any of the variables for
                 the toggle command may be explicitly set or unset using the
                 set and unset commands.
 
                 ayt     If TELNET is in localchars mode, or LINEMODE is
                         enabled, and the status character is typed, a TELNET
                         AYT sequence (see send ayt preceding) is sent to the
                         remote host.  The initial value for the “Are You
                         There” character is the terminal’s status character.
 
                 echo    This is the value (initially “^E”) which, when in
                         “line by line” mode, toggles between doing local echo‐
                         ing of entered characters (for normal processing), and
                         suppressing echoing of entered characters (for enter‐
                         ing, say, a password).
 
                 eof     If telnet is operating in LINEMODE or “old line by
                         line” mode, entering this character as the first char‐
                         acter 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.
 
                 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 char‐
                         acter is taken to be the terminal’s erase character.
 
                 escape  This is the telnet escape character (initially “^[”)
                         which causes entry into telnet command mode (when con‐
                         nected to a remote system).
 
                 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 charac‐
                         ter is taken to be the terminal’s flush character.
 
                 forw1
 
                 forw2   If telnet is operating in LINEMODE, these are the
                         characters that, when typed, cause partial lines to be
                         forwarded to the remote system.  The initial value for
                         the forwarding characters are taken from the termi‐
                         nal’s eol and eol2 characters.
 
                 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.
 
                 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 charac‐
                         ter is taken to be the terminal’s kill character.
 
                 lnext   If telnet is operating in LINEMODE or “old line by
                         line” mode, then this character is taken to be the
                         terminal’s lnext character.  The initial value for the
                         lnext character is taken to be the terminal’s lnext
                         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.
 
                 reprint
                         If telnet is operating in LINEMODE or “old line by
                         line” mode, then this character is taken to be the
                         terminal’s reprint character.  The initial value for
                         the reprint character is taken to be the terminal’s
                         reprint character.
 
                 rlogin  This is the rlogin escape character.  If set, the nor‐
                         mal telnet escape character is ignored unless it is
                         preceded by this character at the beginning of a line.
                         This character, at the beginning of a line followed by
                         a "."  closes the connection; when followed by a ^Z it
                         suspends the telnet command.  The initial state is to
                         disable the rlogin escape character.
 
                 start   If the TELNET TOGGLE-FLOW-CONTROL option has been
                         enabled, then this character is taken to be the termi‐
                         nal’s start character.  The initial value for the
                         start character is taken to be the terminal’s start
                         character.
 
                 stop    If the TELNET TOGGLE-FLOW-CONTROL option has been
                         enabled, then this character is taken to be the termi‐
                         nal’s stop character.  The initial value for the stop
                         character is taken to be the terminal’s stop charac‐
                         ter.
 
                 susp    If telnet is in localchars mode, or LINEMODE is
                         enabled, and the suspend character is typed, a TELNET
                         SUSP sequence (see send susp above) is sent to the
                         remote host.  The initial value for the suspend char‐
                         acter is taken to be the terminal’s suspend character.
 
                 tracefile
                         This is the file to which the output, caused by
                         netdata or option tracing being TRUE, will be written.
                         If it is set to “-”, then tracing information will be
                         written to standard output (the default).
 
                 worderase
                         If telnet is operating in LINEMODE or “old line by
                         line” mode, then this character is taken to be the
                         terminal’s worderase character.  The initial value for
                         the worderase character is taken to be the terminal’s
                         worderase character.
 
                 ?       Displays the legal set (unset) commands.
 
      skey sequence challenge
                 The skey command computes a response to the S/Key challenge.
 
      slc state  The slc command (Set Local Characters) is used to set or
                 change the state of the special characters when the TELNET
                 LINEMODE option has been enabled.  Special characters are
                 characters that get mapped to TELNET commands sequences (like
                 ip or quit) or line editing characters (like erase and kill).
                 By default, the local special characters are exported.
 
                 check       Verify the current settings for the current spe‐
                             cial characters.  The remote side is requested to
                             send all the current special character settings,
                             and if there are any discrepancies with the local
                             side, the local side will switch to the remote
                             value.
 
                 export      Switch to the local defaults for the special char‐
                             acters.  The local default characters are those of
                             the local terminal at the time when telnet was
                             started.
 
                 import      Switch to the remote defaults for the special
                             characters.  The remote default characters are
                             those of the remote system at the time when the
                             TELNET connection was established.
 
                 ?           Prints out help information for the slc command.
 
      status     Show the current status of telnet.  This includes the peer one
                 is connected to, as well as the current mode.
 
      toggle arguments ...
                 Toggle (between TRUE and FALSE) various flags that control how
                 telnet responds to events.  These flags may be set explicitly
                 to TRUE or FALSE using the set and unset commands listed
                 above.  More than one argument may be specified.  The state of
                 these flags may be interrogated with the display command.
                 Valid arguments are:
 
                 authdebug     Turns on debugging information for the authenti‐
                               cation code.
 
                 autoflush     If autoflush and localchars are both TRUE, then
                               when the ao, 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)).
 
                 autodecrypt   When the TELNET ENCRYPT option is negotiated, by
                               default the actual encryption (decryption) of
                               the data stream does not start automatically.
                               The autoencrypt (autodecrypt) command states
                               that encryption of the output (input) stream
                               should be enabled as soon as possible.
 
                 autologin     If the remote side supports the TELNET
                               AUTHENTICATION option telnet attempts to use it
                               to perform automatic authentication.  If the
                               AUTHENTICATION option is not supported, the
                               user’s login name are propagated through the
                               TELNET ENVIRON option.  This command is the same
                               as specifying -a option on the open command.
 
                 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.
 
                 binary        Enable or disable the TELNET BINARY option on
                               both input and output.
 
                 inbinary      Enable or disable the TELNET BINARY option on
                               input.
 
                 outbinary     Enable or disable the TELNET BINARY option on
                               output.
 
                 crlf          If this is TRUE, then carriage returns will be
                               sent as <CR><LF>.  If this is FALSE, then car‐
                               riage returns will be send as <CR><NUL>.  The
                               initial value for 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 super user).  The initial value for this
                               toggle is FALSE.
 
                 encdebug      Turns on debugging information for the encryp‐
                               tion code.
 
                 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 “old line by line” mode, and FALSE in
                               “character at a time” mode.  When the LINEMODE
                               option is enabled, the value of localchars is
                               ignored, and assumed to always be TRUE.  If
                               LINEMODE has ever been enabled, then quit is
                               sent as abort, and eof and suspend are sent as
                               eof and susp (see send above).
 
                 netdata       Toggles the display of all network data (in hex‐
                               adecimal format).  The initial value for this
                               toggle is FALSE.
 
                 options       Toggles the display of some internal telnet pro‐
                               tocol processing (having to do with TELNET
                               options).  The initial value for this toggle is
                               FALSE.
 
                 prettydump    When the netdata toggle is enabled, if
                               prettydump is enabled the output from the
                               netdata command will be formatted in a more user
                               readable format.  Spaces are put between each
                               character in the output, and the beginning of
                               any telnet escape sequence is preceded by a ’*’
                               to aid in locating them.
 
                 skiprc        When the skiprc toggle is TRUE, telnet skips the
                               reading of the .telnetrc file in the users home
                               directory when connections are opened.  The ini‐
                               tial value for this toggle is FALSE.
 
                 termdata      Toggles the display of all terminal data (in
                               hexadecimal format).  The initial value for this
                               toggle is FALSE.
 
                 verbose_encrypt
                               When the verbose_encrypt toggle is TRUE, telnet
                               prints out a message each time encryption is
                               enabled or disabled.  The initial value for this
                               toggle is FALSE.
 
                 ?             Displays the legal toggle commands.
 
      z          Suspend telnet.  This command only works when the user is
                 using the csh(1).
 
      ! [command]
                 Execute a single command in a subshell on the local system.
                 If command is omitted, then an interactive subshell is
                 invoked.
 
      ? [command]
                 Get help.  With no arguments, telnet prints a help summary.
                 If command is specified, telnet will print the help informa‐
                 tion for just that command.
 

ENVIRONMENT

      The telnet utility uses at least the HOME, SHELL, DISPLAY, and TERM envi‐
      ronment variables.  Other environment variables may be propagated to the
      other side via the TELNET ENVIRON option.
      rlogin(1), rsh(1), hosts(5), nologin(5), telnetd(8)
 

FILES

      ~/.telnetrc  user customized telnet startup values
 

HISTORY

      The telnet command appeared in 4.2BSD.
 
      IPv6 support was added by WIDE/KAME project.
 

NOTES

      On some remote systems, echo has to be turned off manually when in “old
      line by line” mode.
 
      In “old line by line” mode or LINEMODE the terminal’s eof character is
      only recognized (and sent to the remote system) when it is the first
      character on a line.
 

Sections

Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon), amd64 compatible (including Opteron, Athlon64, and EM64T), UltraSPARC, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.