1.\" $OpenBSD: telnet.1,v 1.64 2020/01/16 16:46:47 schwarze Exp $ 2.\" $NetBSD: telnet.1,v 1.5 1996/02/28 21:04:12 thorpej Exp $ 3.\" 4.\" Copyright (c) 1983, 1990, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" from: @(#)telnet.1 8.4 (Berkeley) 2/3/94 32.\" 33.Dd $Mdocdate: January 16 2020 $ 34.Dt TELNET 1 35.Os 36.Sh NAME 37.Nm telnet 38.Nd user interface to the TELNET protocol 39.Sh SYNOPSIS 40.Nm telnet 41.Bk -words 42.Op Fl 4678acDEKLr 43.Op Fl b Ar hostalias 44.Op Fl e Ar escapechar 45.Op Fl l Ar user 46.Op Fl n Ar tracefile 47.Op Fl V Ar rtable 48.Oo 49.Ar host 50.Op Ar port 51.Oc 52.Ek 53.Sh DESCRIPTION 54The 55.Nm 56command 57is used to communicate with another host using the TELNET protocol. 58If 59.Nm 60is invoked without the 61.Ar host 62argument, it enters command mode, 63indicated by its prompt 64.Pq Nm telnet\&> . 65In this mode, it accepts and executes the commands listed below. 66If it is invoked with arguments, it performs an 67.Ic open 68command with those arguments. 69.Pp 70The options are as follows: 71.Bl -tag -width Ds 72.It Fl 4 73Forces 74.Nm 75to use IPv4 addresses only. 76.It Fl 6 77Forces 78.Nm 79to use IPv6 addresses only. 80.It Fl 7 81Specifies a 7-bit data path. 82This attempts to disable the 83.Dv TELNET BINARY 84option on both input and output. 85.It Fl 8 86Specifies an 8-bit data path. 87This attempts to negotiate the 88.Dv TELNET BINARY 89option on both input and output. 90This is the default. 91.It Fl a 92Attempt automatic login. 93Currently, this sends the user name via the 94.Ev USER 95variable 96of the 97.Ev ENVIRON 98option if supported by the remote system. 99The name used is that of the current user as returned by 100.Xr getlogin 2 101if it agrees with the current user ID, 102otherwise it is the name associated with the user ID. 103.It Fl b Ar hostalias 104Uses 105.Xr bind 2 106on the local socket to bind it to an aliased address (see 107.Xr ifconfig 8 108and the 109.Cm alias 110specifier) or to the address of 111another interface than the one naturally chosen by 112.Xr connect 2 . 113This can be useful when connecting to services which use IP addresses 114for authentication and reconfiguration of the server is undesirable (or 115impossible). 116.It Fl c 117Disables the reading of the user's 118.Pa \&.telnetrc 119file. 120(See the 121.Ic toggle skiprc 122command on this man page.) 123.It Fl D 124Disables rewriting of the 125.Ev DISPLAY 126variable when it starts with 127.Sq :\& 128or 129.Sq unix: . 130By default, these are replaced with the local hostname and a colon. 131.It Fl E 132Stops any character from being recognized as an escape character. 133.It Fl e Ar escapechar 134Sets the initial 135.Nm 136escape character to 137.Ar escapechar . 138If 139.Ar escapechar 140is omitted, then 141there will be no escape character. 142.It Fl K 143Specifies no automatic login to the remote system. 144.It Fl L 145Specifies an 8-bit data path on output. 146This attempts to negotiate the 147.Dv TELNET BINARY 148option on output. 149.It Fl l Ar user 150When connecting to the remote system, if the remote system 151understands the 152.Ev ENVIRON 153option, then 154.Ar user 155will be sent to the remote system as the value for the variable USER. 156This option implies the 157.Fl a 158option. 159This option may also be used with the 160.Ic open 161command. 162.It Fl n Ar tracefile 163Opens 164.Ar tracefile 165for recording trace information. 166This is the file to which the output, caused by 167.Ic netdata 168or 169.Ic option 170tracing being 171.Dv TRUE , 172will be written. 173If it is set to 174.Dq Fl , 175then tracing information will be written to standard output (the default). 176.It Fl r 177Specifies a user interface similar to 178.Nm rlogin . 179In this 180mode, the escape character is set to the tilde (~) character, 181unless modified by the 182.Fl e 183option. 184.It Fl V Ar rtable 185Set the routing table to be used. 186.It Ar host 187Indicates the official name, an alias, or the Internet address 188of a remote host. 189.It Ar port 190Indicates a port number (address of an application). 191If a number is not specified, the default 192.Nm 193port is used. 194.El 195.Pp 196When in rlogin mode, a line of the form ~.\& 197disconnects from the 198remote host; ~ is the telnet escape character. 199Similarly, the line ~^Z suspends the telnet session. 200The line ~^] escapes to the normal telnet escape prompt. 201.Pp 202Once a connection has been opened, 203.Nm 204will attempt to enable the 205.Dv TELNET LINEMODE 206option. 207If this fails, 208.Nm 209will revert to one of two input modes: 210either 211.Dq character at a time 212or 213.Dq old line by line 214depending on what the remote system supports. 215.Pp 216When 217.Dv LINEMODE 218is enabled, character processing is done on the 219local system, under the control of the remote system. 220When input 221editing or character echoing is to be disabled, the remote system 222will relay that information. 223The remote system will also relay 224changes to any special characters that happen on the remote 225system, so that they can take effect on the local system. 226.Pp 227In 228.Dq character at a time 229mode, most 230text typed is immediately sent to the remote host for processing. 231.Pp 232In 233.Dq old line by line 234mode, all text is echoed locally, 235and (normally) only completed lines are sent to the remote host. 236The local echo character 237.Pq initially Sq ^E 238may be used 239to turn off and on the local echo 240(this would mostly be used to enter passwords 241without the password being echoed). 242.Pp 243If the 244.Dv LINEMODE 245option is enabled, or if the 246.Ic localchars 247toggle is 248.Dv TRUE 249(the default for 250.Dq old line by line ; 251see below), 252the user's 253.Ic quit , 254.Ic intr , 255and 256.Ic flush 257characters are trapped locally, and sent as TELNET 258protocol sequences to the remote side. 259If 260.Dv LINEMODE 261has ever been enabled, then the user's 262.Ic susp 263and 264.Ic eof 265are also sent as TELNET protocol sequences, and 266.Ic quit 267is sent as a 268.Dv TELNET ABORT 269instead of 270.Dv BREAK . 271There are options (see 272.Ic toggle 273.Ic autoflush 274and 275.Ic toggle 276.Ic autosynch 277below) 278which cause this action to flush subsequent output to the terminal 279(until the remote host acknowledges the TELNET 280sequence) and flush previous terminal input 281(in the case of 282.Ic quit 283and 284.Ic intr ) . 285.Pp 286While connected to a remote host, 287.Nm 288command mode may be entered by typing the 289.Nm 290escape character 291.Pq initially Sq ^] . 292When in command mode, the normal terminal editing conventions are available. 293Note that the escape character will return to the command mode of the initial 294invocation of 295.Nm 296that has the controlling terminal. 297Use the 298.Cm send escape 299command to switch to command mode in subsequent 300.Nm 301processes on remote hosts. 302.Pp 303The following 304.Nm 305commands are available. 306Only enough of each command to uniquely identify it need be typed 307(this is also true for arguments to the 308.Ic mode , 309.Ic set , 310.Ic toggle , 311.Ic unset , 312.Ic slc , 313.Ic environ , 314and 315.Ic display 316commands). 317.Bl -tag -width "mode type" 318.It Ic close 319Close a TELNET session and return to command mode. 320.It Ic display Ar argument ... 321Displays all, or some, of the 322.Ic set 323and 324.Ic toggle 325values (see below). 326.It Ic environ Ar argument ... 327The 328.Ic environ 329command is used to manipulate the 330variables that may be sent through the 331.Dv TELNET ENVIRON 332option. 333The initial set of variables is taken from the users 334environment, with only the 335.Ev DISPLAY 336and 337.Ev PRINTER 338variables being exported by default. 339The 340.Ev USER 341variable is also exported if the 342.Fl a 343or 344.Fl l 345options are used. 346.Pp 347Valid arguments for the 348.Ic environ 349command are: 350.Bl -tag -width Ds 351.It Ic define Ar variable value 352Define the variable 353.Ar variable 354to have a value of 355.Ar value . 356Any variables defined by this command are automatically exported. 357The 358.Ar value 359may be enclosed in single or double quotes so 360that tabs and spaces may be included. 361.It Ic undefine Ar variable 362Remove 363.Ar variable 364from the list of environment variables. 365.It Ic export Ar variable 366Mark the variable 367.Ar variable 368to be exported to the remote side. 369.It Ic unexport Ar variable 370Mark the variable 371.Ar variable 372to not be exported unless 373explicitly asked for by the remote side. 374.It Ic list 375List the current set of environment variables. 376Those marked with a 377.Cm * 378will be sent automatically, 379other variables will only be sent if explicitly requested. 380.It Ic \&? 381Prints out help information for the 382.Ic environ 383command. 384.El 385.It Ic logout 386Sends the 387.Dv TELNET LOGOUT 388option to the remote side. 389This command is similar to a 390.Ic close 391command; however, if the remote side does not support the 392.Dv LOGOUT 393option, nothing happens. 394If, however, the remote side does support the 395.Dv LOGOUT 396option, this command should cause the remote side to close the TELNET 397connection. 398If the remote side also supports the concept of 399suspending a user's session for later reattachment, 400the logout argument indicates that you 401should terminate the session immediately. 402.It Ic mode Ar type 403.Ar type 404is one of several options, depending on the state of the TELNET 405session. 406The remote host is asked for permission to go into the requested mode. 407If the remote host is capable of entering that mode, the requested 408mode will be entered. 409.Bl -tag -width Ar 410.It Ic character 411Disable the 412.Dv TELNET LINEMODE 413option or, if the remote side does not understand the 414.Dv LINEMODE 415option, then enter 416.Dq character at a time 417mode. 418.It Ic line 419Enable the 420.Dv TELNET LINEMODE 421option or, if the remote side does not understand the 422.Dv LINEMODE 423option, then attempt to enter 424.Dq old line by line 425mode. 426.It Ic isig Pq Ic \-isig 427Attempt to enable (disable) the 428.Dv TRAPSIG 429mode of the 430.Dv LINEMODE 431option. 432This requires that the 433.Dv LINEMODE 434option be enabled. 435.It Ic edit Pq Ic \-edit 436Attempt to enable (disable) the 437.Dv EDIT 438mode of the 439.Dv LINEMODE 440option. 441This requires that the 442.Dv LINEMODE 443option be enabled. 444.It Ic softtabs Pq Ic \-softtabs 445Attempt to enable (disable) the 446.Dv SOFT_TAB 447mode of the 448.Dv LINEMODE 449option. 450This requires that the 451.Dv LINEMODE 452option be enabled. 453.It Ic litecho Pq Ic \-litecho 454Attempt to enable (disable) the 455.Dv LIT_ECHO 456mode of the 457.Dv LINEMODE 458option. 459This requires that the 460.Dv LINEMODE 461option be enabled. 462.It Ic \&? 463Prints out help information for the 464.Ic mode 465command. 466.El 467.It Xo 468.Ic open Ar host 469.Op Fl a 470.Op Fl b hostalias 471.Op Fl l Ar user 472.Oo Op Fl 473.Ar port Oc 474.Xc 475Open a connection to the named host. 476If no port number 477is specified, 478.Nm 479will attempt to contact a TELNET server at the default port. 480The host specification may be either a host name (see 481.Xr hosts 5 ) 482or an Internet address specified in the 483.Dq dot notation 484(see 485.Xr inet_ntop 3 ) . 486The 487.Fl a , 488.Fl b , 489and 490.Fl l 491options are equivalent to the identical command line options, 492but only apply to the new telnet connection being opened. 493When connecting to a non-standard port, 494.Nm 495omits any automatic initiation of TELNET options. 496When the port number is preceded by a minus sign, 497the initial option negotiation is done. 498After establishing a connection, the file 499.Pa \&.telnetrc 500in the 501user's home directory is opened. 502Lines beginning with a 503.Sq # 504are comment lines. 505Blank lines are ignored. 506Lines that begin 507without whitespace are the start of a machine entry. 508The first thing on the line is the name of the machine that is 509being connected to. 510The rest of the line, and successive 511lines that begin with whitespace are assumed to be 512.Nm 513commands and are processed as if they had been typed 514in manually to the 515.Nm 516command prompt. 517.It Ic quit 518Close any open TELNET session and exit 519.Nm telnet . 520An end-of-file (in command mode) will also close a session and exit. 521.It Ic send Ar argument ... 522Sends one or more special character sequences to the remote host. 523The following are the arguments which may be specified 524(more than one argument may be specified at a time): 525.Bl -tag -width Ds 526.It Ic abort 527Sends the 528.Dv TELNET ABORT 529(Abort 530processes) 531sequence. 532.It Ic ao 533Sends the 534.Dv TELNET AO 535(Abort Output) sequence, which should cause the remote system to flush 536all output 537.Em from 538the remote system 539.Em to 540the user's terminal. 541.It Ic ayt 542Sends the 543.Dv TELNET AYT 544(Are You There) 545sequence, to which the remote system may or may not choose to respond. 546.It Ic brk 547Sends the 548.Dv TELNET BRK 549(Break) sequence, which may have significance to the remote 550system. 551.It Ic ec 552Sends the 553.Dv TELNET EC 554(Erase Character) 555sequence, which should cause the remote system to erase the last character 556entered. 557.It Ic el 558Sends the 559.Dv TELNET EL 560(Erase Line) 561sequence, which should cause the remote system to erase the line currently 562being entered. 563.It Ic eof 564Sends the 565.Dv TELNET EOF 566(End Of File) 567sequence. 568.It Ic eor 569Sends the 570.Dv TELNET EOR 571(End of Record) 572sequence. 573.It Ic escape 574Sends the current 575.Nm 576escape character 577.Pq initially Sq ^] . 578.It Ic ga 579Sends the 580.Dv TELNET GA 581(Go Ahead) 582sequence, which likely has no significance to the remote system. 583.It Ic getstatus 584If the remote side supports the 585.Dv TELNET STATUS 586command, 587.Ic getstatus 588will send the subnegotiation to request that the server send 589its current option status. 590.It Ic ip 591Sends the 592.Dv TELNET IP 593(Interrupt Process) sequence, which should cause the remote 594system to abort the currently running process. 595.It Ic nop 596Sends the 597.Dv TELNET NOP 598(No OPeration) 599sequence. 600.It Ic susp 601Sends the 602.Dv TELNET SUSP 603(SUSPend process) 604sequence. 605.It Ic synch 606Sends the 607.Dv TELNET SYNCH 608sequence. 609This sequence causes the remote system to discard all previously typed 610(but not yet read) input. 611This sequence is sent as TCP urgent 612data (and may not work if the remote system is a 613.Bx 4.2 614system \(em if it doesn't work, a lower case 615.Sq r 616may be echoed on the terminal). 617.It Ic do Ar cmd 618Sends the 619.Dv TELNET DO 620.Ar cmd 621sequence. 622.Ar cmd 623can be either a decimal number between 0 and 255, 624or a symbolic name for a specific TELNET command. 625.Ar cmd 626can also be either 627.Ic help 628or 629.Ic ?\& 630to print out help information, including 631a list of known symbolic names. 632.It Ic dont Ar cmd 633Sends the 634.Dv TELNET DONT 635.Ar cmd 636sequence. 637.Ar cmd 638can be either a decimal number between 0 and 255, 639or a symbolic name for a specific TELNET command. 640.Ar cmd 641can also be either 642.Ic help 643or 644.Ic ?\& 645to print out help information, including 646a list of known symbolic names. 647.It Ic will Ar cmd 648Sends the 649.Dv TELNET WILL 650.Ar cmd 651sequence. 652.Ar cmd 653can be either a decimal number between 0 and 255, 654or a symbolic name for a specific TELNET command. 655.Ar cmd 656can also be either 657.Ic help 658or 659.Ic ?\& 660to print out help information, including 661a list of known symbolic names. 662.It Ic wont Ar cmd 663Sends the 664.Dv TELNET WONT 665.Ar cmd 666sequence. 667.Ar cmd 668can be either a decimal number between 0 and 255, 669or a symbolic name for a specific TELNET command. 670.Ar cmd 671can also be either 672.Ic help 673or 674.Ic ?\& 675to print out help information, including 676a list of known symbolic names. 677.It Ic \&? 678Prints out help information for the 679.Ic send 680command. 681.El 682.It Ic set Ar argument value 683.It Ic unset Ar argument value 684The 685.Ic set 686command will set any one of a number of 687.Nm 688variables to a specific value or to 689.Dv TRUE . 690The special value 691.Ic off 692turns off the function associated with 693the variable; this is equivalent to using the 694.Ic unset 695command. 696The 697.Ic unset 698command will disable or set to 699.Dv FALSE 700any of the specified functions. 701The values of variables may be interrogated with the 702.Ic display 703command. 704The variables which may be set or unset, but not toggled, are 705listed here. 706In addition, any of the variables for the 707.Ic toggle 708command may be explicitly set or unset using 709the 710.Ic set 711and 712.Ic unset 713commands. 714.Bl -tag -width Ds 715.It Ic ayt 716If TELNET is in 717.Ic localchars 718mode, or 719.Dv LINEMODE 720is enabled, and the status character is typed, a 721.Dv TELNET AYT 722sequence (see 723.Ic send ayt 724preceding) is sent to the 725remote host. 726The initial value for the "Are You There" 727character is the terminal's status character. 728.It Ic echo 729This is the value 730.Pq initially Sq ^E 731which, when in 732.Dq line by line 733mode, toggles between doing local echoing 734of entered characters (for normal processing), and suppressing 735echoing of entered characters (for entering, say, a password). 736.It Ic eof 737If 738.Nm 739is operating in 740.Dv LINEMODE 741or 742.Dq old line by line 743mode, entering this character 744as the first character on a line will cause this character to be 745sent to the remote system. 746The initial value of the 747.Ic eof 748character is taken to be the terminal's 749.Ic eof 750character. 751.It Ic erase 752If 753.Nm 754is in 755.Ic localchars 756mode (see 757.Ic toggle 758.Ic localchars 759below), 760and if 761.Nm 762is operating in 763.Dq character at a time 764mode, then when this character is typed, a 765.Dv TELNET EC 766sequence (see 767.Ic send 768.Ic ec 769above) 770is sent to the remote system. 771The initial value for the 772.Ic erase 773character is taken to be 774the terminal's 775.Ic erase 776character. 777.It Ic escape 778This is the 779.Nm 780escape character 781.Pq initially Sq ^[ 782which causes entry into 783.Nm 784command mode (when connected to a remote system). 785.It Ic flushoutput 786If 787.Nm 788is in 789.Ic localchars 790mode (see 791.Ic toggle 792.Ic localchars 793below) 794and the 795.Ic flushoutput 796character is typed, a 797.Dv TELNET AO 798sequence (see 799.Ic send 800.Ic ao 801above) 802is sent to the remote host. 803The initial value for the 804.Ic flush 805character is taken to be 806the terminal's 807.Ic flush 808character. 809.It Ic forw1 810.It Ic forw2 811If TELNET is operating in 812.Dv LINEMODE , 813these are the 814characters that, when typed, cause partial lines to be 815forwarded to the remote system. 816The initial value for 817the forwarding characters are taken from the terminal's 818eol and eol2 characters. 819.It Ic interrupt 820If 821.Nm 822is in 823.Ic localchars 824mode (see 825.Ic toggle 826.Ic localchars 827below) 828and the 829.Ic interrupt 830character is typed, a 831.Dv TELNET IP 832sequence (see 833.Ic send 834.Ic ip 835above) 836is sent to the remote host. 837The initial value for the 838.Ic interrupt 839character is taken to be 840the terminal's 841.Ic intr 842character. 843.It Ic kill 844If 845.Nm 846is in 847.Ic localchars 848mode (see 849.Ic toggle 850.Ic localchars 851below), 852and if 853.Nm 854is operating in 855.Dq character at a time 856mode, then when this character is typed, a 857.Dv TELNET EL 858sequence (see 859.Ic send 860.Ic el 861above) 862is sent to the remote system. 863The initial value for the 864.Ic kill 865character is taken to be 866the terminal's 867.Ic kill 868character. 869.It Ic lnext 870If 871.Nm 872is operating in 873.Dv LINEMODE 874or 875.Dq old line by line 876mode, then this character is taken to be the terminal's 877.Ic lnext 878character. 879The initial value for the 880.Ic lnext 881character is taken to be 882the terminal's 883.Ic lnext 884character. 885.It Ic quit 886If 887.Nm 888is in 889.Ic localchars 890mode (see 891.Ic toggle 892.Ic localchars 893below) 894and the 895.Ic quit 896character is typed, a 897.Dv TELNET BRK 898sequence (see 899.Ic send 900.Ic brk 901above) 902is sent to the remote host. 903The initial value for the 904.Ic quit 905character is taken to be 906the terminal's 907.Ic quit 908character. 909.It Ic reprint 910If 911.Nm 912is operating in 913.Dv LINEMODE 914or 915.Dq old line by line 916mode, then this character is taken to be the terminal's 917.Ic reprint 918character. 919The initial value for the 920.Ic reprint 921character is taken to be 922the terminal's 923.Ic reprint 924character. 925.It Ic rlogin 926This is the rlogin escape character. 927If set, the normal TELNET 928escape character is ignored unless it is 929preceded by this character at the beginning of a line. 930This character, at the beginning of a line, followed by 931a "." closes the connection; when followed by a ^Z it 932suspends the 933.Nm 934command. 935The initial state is to 936disable the 937.Ic rlogin 938escape character. 939.It Ic start 940If the 941.Dv TELNET TOGGLE-FLOW-CONTROL 942option has been enabled, 943then this character is taken to 944be the terminal's 945.Ic start 946character. 947The initial value for the 948.Ic start 949character is taken to be 950the terminal's 951.Ic start 952character. 953.It Ic stop 954If the 955.Dv TELNET TOGGLE-FLOW-CONTROL 956option has been enabled, 957then this character is taken to 958be the terminal's 959.Ic stop 960character. 961The initial value for the 962.Ic stop 963character is taken to be 964the terminal's 965.Ic stop 966character. 967.It Ic susp 968If 969.Nm 970is in 971.Ic localchars 972mode, or 973.Dv LINEMODE 974is enabled, and the 975.Ic suspend 976character is typed, a 977.Dv TELNET SUSP 978sequence (see 979.Ic send 980.Ic susp 981above) 982is sent to the remote host. 983The initial value for the 984.Ic suspend 985character is taken to be 986the terminal's 987.Ic suspend 988character. 989.It Ic worderase 990If 991.Nm 992is operating in 993.Dv LINEMODE 994or 995.Dq old line by line 996mode, then this character is taken to be the terminal's 997.Ic worderase 998character. 999The initial value for the 1000.Ic worderase 1001character is taken to be 1002the terminal's 1003.Ic worderase 1004character. 1005.It Ic \&? 1006Displays the legal 1007.Ic set 1008.Pq Ic unset 1009commands. 1010.El 1011.It Ic slc Ar state 1012The 1013.Ic slc 1014command (Set Local Characters) is used to set 1015or change the state of the special 1016characters when the 1017.Dv TELNET LINEMODE 1018option has 1019been enabled. 1020Special characters are characters that get mapped to TELNET 1021commands sequences (like 1022.Ic ip 1023or 1024.Ic quit ) 1025or line editing characters (like 1026.Ic erase 1027and 1028.Ic kill ) . 1029By default, the local special characters are exported. 1030.Bl -tag -width Ds 1031.It Ic check 1032Verify the current settings for the current special characters. 1033The remote side is requested to send all the current special 1034character settings, and if there are any discrepancies with 1035the local side, the local side will switch to the remote value. 1036.It Ic export 1037Switch to the local defaults for the special characters. 1038The local default characters are those of the local terminal at 1039the time when 1040.Nm 1041was started. 1042.It Ic import 1043Switch to the remote defaults for the special characters. 1044The remote default characters are those of the remote system 1045at the time when the TELNET connection was established. 1046.It Ic \&? 1047Prints out help information for the 1048.Ic slc 1049command. 1050.El 1051.It Ic status 1052Show the current status of 1053.Nm telnet . 1054This includes the peer one is connected to, as well 1055as the current mode. 1056.It Ic toggle Ar argument ... 1057Toggle (between 1058.Dv TRUE 1059and 1060.Dv FALSE ) 1061various flags that control how 1062.Nm 1063responds to events. 1064These flags may be set explicitly to 1065.Dv TRUE 1066or 1067.Dv FALSE 1068using the 1069.Ic set 1070and 1071.Ic unset 1072commands listed above. 1073More than one argument may be specified. 1074The state of these flags may be interrogated with the 1075.Ic display 1076command. 1077Valid arguments are: 1078.Bl -tag -width Ar 1079.It Ic autoflush 1080If 1081.Ic autoflush 1082and 1083.Ic localchars 1084are both 1085.Dv TRUE , 1086then when the 1087.Ic ao 1088or 1089.Ic quit 1090characters are recognized (and transformed into TELNET sequences; see 1091.Ic set 1092above for details), 1093.Nm 1094refuses to display any data on the user's terminal 1095until the remote system acknowledges (via a 1096.Dv TELNET TIMING MARK 1097option) 1098that it has processed those TELNET sequences. 1099The initial value for this toggle is 1100.Dv TRUE 1101if the terminal user had not 1102done an "stty noflsh", otherwise 1103.Dv FALSE 1104(see 1105.Xr stty 1 ) . 1106.It Ic autologin 1107The user's login 1108name is propagated through the 1109.Dv TELNET ENVIRON 1110option. 1111This command is the same as specifying 1112.Ar a 1113option on the 1114.Ic open 1115command. 1116.It Ic autosynch 1117If 1118.Ic autosynch 1119and 1120.Ic localchars 1121are both 1122.Dv TRUE , 1123then when either the 1124.Ic intr 1125or 1126.Ic quit 1127character is typed (see 1128.Ic set 1129above for descriptions of the 1130.Ic intr 1131and 1132.Ic quit 1133characters), the resulting TELNET sequence sent is followed by the 1134.Dv TELNET SYNCH 1135sequence. 1136This procedure 1137.Em should 1138cause the remote system to begin throwing away all previously 1139typed input until both of the TELNET 1140sequences have been read and acted upon. 1141The initial value of this toggle is 1142.Dv FALSE . 1143.It Ic binary 1144Enable or disable the 1145.Dv TELNET BINARY 1146option on both input and output. 1147.It Ic inbinary 1148Enable or disable the 1149.Dv TELNET BINARY 1150option on input. 1151.It Ic outbinary 1152Enable or disable the 1153.Dv TELNET BINARY 1154option on output. 1155.It Ic crlf 1156If this is 1157.Dv TRUE , 1158then carriage returns will be sent as 1159.Li <CR><LF> . 1160If this is 1161.Dv FALSE , 1162then carriage returns will be sent as 1163.Li <CR><NUL> . 1164The initial value for this toggle is 1165.Dv FALSE . 1166.It Ic crmod 1167Toggle carriage return mode. 1168When this mode is enabled, most carriage return characters received from 1169the remote host will be mapped into a carriage return followed by 1170a line feed. 1171This mode does not affect those characters typed by the user, only 1172those received from the remote host. 1173This mode is not very useful unless the remote host 1174only sends carriage return, but never line feeds. 1175The initial value for this toggle is 1176.Dv FALSE . 1177.It Ic localchars 1178If this is 1179.Dv TRUE , 1180then the 1181.Ic flush , 1182.Ic interrupt , 1183.Ic quit , 1184.Ic erase , 1185and 1186.Ic kill 1187characters (see 1188.Ic set 1189above) are recognized locally, and transformed into (hopefully) appropriate 1190TELNET control sequences 1191(respectively 1192.Ic ao , 1193.Ic ip , 1194.Ic brk , 1195.Ic ec , 1196and 1197.Ic el ; 1198see 1199.Ic send 1200above). 1201The initial value for this toggle is 1202.Dv TRUE 1203in 1204.Dq old line by line 1205mode, and 1206.Dv FALSE 1207in 1208.Dq character at a time 1209mode. 1210When the 1211.Dv LINEMODE 1212option is enabled, the value of 1213.Ic localchars 1214is ignored, and assumed to always be 1215.Dv TRUE . 1216If 1217.Dv LINEMODE 1218has ever been enabled, then 1219.Ic quit 1220is sent as 1221.Ic abort , 1222and 1223.Ic eof 1224and 1225.Ic suspend 1226are sent as 1227.Ic eof 1228and 1229.Ic susp 1230(see 1231.Ic send 1232above). 1233.It Ic netdata 1234Toggles the display of all network data (in hexadecimal format). 1235The initial value for this toggle is 1236.Dv FALSE . 1237.It Ic options 1238Toggles the display of some internal 1239.Nm 1240protocol processing (having to do with TELNET options). 1241The initial value for this toggle is 1242.Dv FALSE . 1243.It Ic prettydump 1244When the 1245.Ic netdata 1246toggle is enabled, if 1247.Ic prettydump 1248is enabled the output from the 1249.Ic netdata 1250command will be formatted in a more user readable format. 1251Spaces are put between each character in the output, and the 1252beginning of any TELNET 1253escape sequence is preceded by a '*' to aid in locating them. 1254.It Ic skiprc 1255When the skiprc toggle is 1256.Dv TRUE , 1257TELNET skips the reading of the 1258.Pa \&.telnetrc 1259file in the user's home 1260directory when connections are opened. 1261The initial value for this toggle is 1262.Dv FALSE . 1263.It Ic termdata 1264Toggles the display of all terminal data (in hexadecimal format). 1265The initial value for this toggle is 1266.Dv FALSE . 1267.It Ic \&? 1268Displays the legal 1269.Ic toggle 1270commands. 1271.El 1272.It Ic z 1273Suspend 1274.Nm telnet . 1275This command only works when the user is using a shell with 1276job control enabled. 1277.It Ic \&? Op Ar command 1278Get help. 1279With no arguments, 1280.Nm 1281prints a help summary. 1282If a command is specified, 1283.Nm 1284will print the help information for just that command. 1285.El 1286.Sh ENVIRONMENT 1287.Nm 1288uses at least the 1289.Ev HOME , 1290.Ev DISPLAY , 1291and 1292.Ev TERM 1293environment variables. 1294Other environment variables may be propagated 1295to the other side via the 1296.Dv TELNET ENVIRON 1297option. 1298.Sh FILES 1299.Bl -tag -width ~/.telnetrc -compact 1300.It Pa ~/.telnetrc 1301user customized telnet startup values 1302.El 1303.Sh SEE ALSO 1304.Xr ssh 1 , 1305.Xr stty 1 1306.Sh HISTORY 1307The 1308.Nm 1309command appeared in 1310.Bx 4.2 . 1311.Sh NOTES 1312On some remote systems, echo has to be turned off manually when in 1313.Dq old line by line 1314mode. 1315.Pp 1316In 1317.Dq old line by line 1318mode or 1319.Dv LINEMODE 1320the terminal's 1321.Ic eof 1322character is only recognized (and sent to the remote system) 1323when it is the first character on a line. 1324