1.\" Copyright (c) 1983, 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)telnet.1 8.6 (Berkeley) 6/1/94 33.\" 34.Dd June 1, 1994 35.Dt TELNET 1 36.Os BSD 4.2 37.Sh NAME 38.Nm telnet 39.Nd user interface to the 40.Tn TELNET 41protocol 42.Sh SYNOPSIS 43.Nm telnet 44.Op Fl 78EFKLacdfrx 45.Op Fl S Ar tos 46.Op Fl X Ar authtype 47.Op Fl e Ar escapechar 48.Op Fl k Ar realm 49.Op Fl l Ar user 50.Op Fl n Ar tracefile 51.Oo 52.Ar host 53.Op port 54.Oc 55.Sh DESCRIPTION 56The 57.Nm telnet 58command 59is used to communicate with another host using the 60.Tn TELNET 61protocol. 62If 63.Nm telnet 64is invoked without the 65.Ar host 66argument, it enters command mode, 67indicated by its prompt 68.Pq Nm telnet\*[Gt] . 69In this mode, it accepts and executes the commands listed below. 70If it is invoked with arguments, it performs an 71.Ic open 72command with those arguments. 73.Pp 74Options: 75.Bl -tag -width indent 76.It Fl 8 77Specifies an 8-bit data path. This causes an attempt to 78negotiate the 79.Dv TELNET BINARY 80option on both input and output. 81.It Fl 7 82Do not try to negotiate 83.Dv TELNET BINARY 84option. 85.It Fl E 86Stops any character from being recognized as an escape character. 87.It Fl F 88If Kerberos V5 authentication is being used, the 89.Fl F 90option allows the local credentials to be forwarded 91to the remote system, including any credentials that 92have already been forwarded into the local environment. 93.It Fl K 94Specifies no automatic login to the remote system. 95.It Fl L 96Specifies an 8-bit data path on output. This causes the 97BINARY option to be negotiated on output. 98.It Fl S Ar tos 99Sets the IP type-of-service (TOS) option for the telnet 100connection to the value 101.Ar tos , 102which can be a numeric TOS value 103or, on systems that support it, a symbolic 104TOS name found in the /etc/iptos file. 105.It Fl X Ar atype 106Disables the 107.Ar atype 108type of authentication. 109.It Fl a 110Attempt automatic login. 111Currently, this sends the user name via the 112.Ev USER 113variable 114of the 115.Ev ENVIRON 116option if supported by the remote system. 117The name used is that of the current user as returned by 118.Xr getlogin 2 119if it agrees with the current user ID, 120otherwise it is the name associated with the user ID. 121.It Fl c 122Disables the reading of the user's 123.Pa \&.telnetrc 124file. (See the 125.Ic toggle skiprc 126command on this man page.) 127.It Fl d 128Sets the initial value of the 129.Ic debug 130toggle to 131.Dv TRUE 132.It Fl e Ar escape char 133Sets the initial 134.Nm 135.Nm telnet 136escape character to 137.Ar escape char . 138If 139.Ar escape char 140is omitted, then 141there will be no escape character. 142.It Fl f 143If Kerberos V5 authentication is being used, the 144.Fl f 145option allows the local credentials to be forwarded to the remote system. 146.It Fl k Ar realm 147If Kerberos authentication is being used, the 148.Fl k 149option requests that telnet obtain tickets for the remote host in 150realm realm instead of the remote host's realm, as determined 151by 152.Xr krb_realmofhost 3 . 153.It Fl l Ar user 154When connecting to the remote system, if the remote system 155understands the 156.Ev ENVIRON 157option, then 158.Ar user 159will be sent to the remote system as the value for the variable USER. 160This option implies the 161.Fl a 162option. 163This option may also be used with the 164.Ic open 165command. 166.It Fl n Ar tracefile 167Opens 168.Ar tracefile 169for recording trace information. 170See the 171.Ic set tracefile 172command below. 173.It Fl r 174Specifies a user interface similar to 175.Xr rlogin 1 . 176In this 177mode, the escape character is set to the tilde (~) character, 178unless modified by the -e option. 179.It Fl x 180Turn on encryption of the data stream. When this option is turned on, 181.B telnet 182will exit with an error if authentication cannot be negotiated or if 183encryption cannot be turned on. 184.It Ar host 185Indicates the official name, an alias, or the Internet address 186of a remote host. 187.It Ar port 188Indicates a port number (address of an application). If a number is 189not specified, the default 190.Nm telnet 191port is used. 192.El 193.Pp 194When in rlogin mode, a line of the form ~. disconnects from the 195remote host; ~ is the telnet escape character. 196Similarly, the line ~^Z suspends the telnet session. 197The line ~^] escapes to the normal telnet escape prompt. 198.Pp 199Once a connection has been opened, 200.Nm telnet 201will attempt to enable the 202.Dv TELNET LINEMODE 203option. 204If this fails, then 205.Nm telnet 206will revert to one of two input modes: 207either \*(Lqcharacter at a time\*(Rq 208or \*(Lqold line by line\*(Rq 209depending on what the remote system supports. 210.Pp 211When 212.Dv LINEMODE 213is enabled, character processing is done on the 214local system, under the control of the remote system. When input 215editing or character echoing is to be disabled, the remote system 216will relay that information. The remote system will also relay 217changes to any special characters that happen on the remote 218system, so that they can take effect on the local system. 219.Pp 220In \*(Lqcharacter at a time\*(Rq mode, most 221text typed is immediately sent to the remote host for processing. 222.Pp 223In \*(Lqold line by line\*(Rq mode, all text is echoed locally, 224and (normally) only completed lines are sent to the remote host. 225The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used 226to turn off and on the local echo 227(this would mostly be used to enter passwords 228without the password being echoed). 229.Pp 230If the 231.Dv LINEMODE 232option is enabled, or if the 233.Ic localchars 234toggle is 235.Dv TRUE 236(the default for \*(Lqold line by line\*(Lq; see below), 237the user's 238.Ic quit , 239.Ic intr , 240and 241.Ic flush 242characters are trapped locally, and sent as 243.Tn TELNET 244protocol sequences to the remote side. 245If 246.Dv LINEMODE 247has ever been enabled, then the user's 248.Ic susp 249and 250.Ic eof 251are also sent as 252.Tn TELNET 253protocol sequences, 254and 255.Ic quit 256is sent as a 257.Dv TELNET ABORT 258instead of 259.Dv BREAK 260There are options (see 261.Ic toggle 262.Ic autoflush 263and 264.Ic toggle 265.Ic autosynch 266below) 267which cause this action to flush subsequent output to the terminal 268(until the remote host acknowledges the 269.Tn TELNET 270sequence) and flush previous terminal input 271(in the case of 272.Ic quit 273and 274.Ic intr ) . 275.Pp 276While connected to a remote host, 277.Nm telnet 278command mode may be entered by typing the 279.Nm telnet 280\*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq). 281When in command mode, the normal terminal editing conventions are available. 282.Pp 283The following 284.Nm telnet 285commands are available. 286Only enough of each command to uniquely identify it need be typed 287(this is also true for arguments to the 288.Ic mode , 289.Ic set , 290.Ic toggle , 291.Ic unset , 292.Ic slc , 293.Ic environ , 294and 295.Ic display 296commands). 297.Pp 298.Bl -tag -width "mode type" 299.It Ic auth Ar argument ... 300The auth command manipulates the information sent through the 301.Dv TELNET AUTHENTICATE 302option. Valid arguments for the 303auth command are as follows: 304.Bl -tag -width "disable type" 305.It Ic disable Ar type 306Disables the specified type of authentication. To 307obtain a list of available types, use the 308.Ic auth disable ?\& 309command. 310.It Ic enable Ar type 311Enables the specified type of authentication. To 312obtain a list of available types, use the 313.Ic auth enable ?\& 314command. 315.It Ic status 316Lists the current status of the various types of 317authentication. 318.El 319.It Ic close 320Close a 321.Tn TELNET 322session and return to command mode. 323.It Ic display Ar argument ... 324Displays all, or some, of the 325.Ic set 326and 327.Ic toggle 328values (see below). 329.It Ic encrypt Ar argument ... 330The encrypt command manipulates the information sent through the 331.Dv TELNET ENCRYPT 332option. 333.Pp 334Note: Because of export controls, the 335.Dv TELNET ENCRYPT 336option is not supported outside of the United States and Canada. 337.Pp 338Valid arguments for the encrypt command are as follows: 339.Bl -tag -width Ar 340.It Ic disable Ar type Xo 341.Op Cm input | output 342.Xc 343Disables the specified type of encryption. If you 344omit the input and output, both input and output 345are disabled. To obtain a list of available 346types, use the 347.Ic encrypt disable ?\& 348command. 349.It Ic enable Ar type Xo 350.Op Cm input | output 351.Xc 352Enables the specified type of encryption. If you 353omit input and output, both input and output are 354enabled. To obtain a list of available types, use the 355.Ic encrypt enable ?\& 356command. 357.It Ic input 358This is the same as the 359.Ic encrypt start input 360command. 361.It Ic -input 362This is the same as the 363.Ic encrypt stop input 364command. 365.It Ic output 366This is the same as the 367.Ic encrypt start output 368command. 369.It Ic -output 370This is the same as the 371.Ic encrypt stop output 372command. 373.It Ic start Op Cm input | output 374Attempts to start encryption. If you omit 375.Ic input 376and 377.Ic output , 378both input and output are enabled. To 379obtain a list of available types, use the 380.Ic encrypt enable ?\& 381command. 382.It Ic status 383Lists the current status of encryption. 384.It Ic stop Op Cm input | output 385Stops encryption. If you omit input and output, 386encryption is on both input and output. 387.It Ic type Ar type 388Sets the default type of encryption to be used 389with later 390.Ic encrypt start 391or 392.Ic encrypt stop 393commands. 394.El 395.It Ic environ Ar arguments ... 396The 397.Ic environ 398command is used to manipulate the 399the variables that my be sent through the 400.Dv TELNET ENVIRON 401option. 402The initial set of variables is taken from the users 403environment, with only the 404.Ev DISPLAY 405and 406.Ev PRINTER 407variables being exported by default. 408The 409.Ev USER 410variable is also exported if the 411.Fl a 412or 413.Fl l 414options are used. 415.Pp 416Valid arguments for the 417.Ic environ 418command are: 419.Bl -tag -width Fl 420.It Ic define Ar variable value 421Define the variable 422.Ar variable 423to have a value of 424.Ar value . 425Any variables defined by this command are automatically exported. 426The 427.Ar value 428may be enclosed in single or double quotes so 429that tabs and spaces may be included. 430.It Ic undefine Ar variable 431Remove 432.Ar variable 433from the list of environment variables. 434.It Ic export Ar variable 435Mark the variable 436.Ar variable 437to be exported to the remote side. 438.It Ic unexport Ar variable 439Mark the variable 440.Ar variable 441to not be exported unless 442explicitly asked for by the remote side. 443.It Ic list 444List the current set of environment variables. 445Those marked with a 446.Cm * 447will be sent automatically, 448other variables will only be sent if explicitly requested. 449.It Ic ?\& 450Prints out help information for the 451.Ic environ 452command. 453.El 454.It Ic logout 455Sends the 456.Dv TELNET LOGOUT 457option to the remote side. 458This command is similar to a 459.Ic close 460command; however, if the remote side does not support the 461.Dv LOGOUT 462option, nothing happens. 463If, however, the remote side does support the 464.Dv LOGOUT 465option, this command should cause the remote side to close the 466.Tn TELNET 467connection. 468If the remote side also supports the concept of 469suspending a user's session for later reattachment, 470the logout argument indicates that you 471should terminate the session immediately. 472.It Ic mode Ar type 473.Ar Type 474is one of several options, depending on the state of the 475.Tn TELNET 476session. 477The remote host is asked for permission to go into the requested mode. 478If the remote host is capable of entering that mode, the requested 479mode will be entered. 480.Bl -tag -width Ar 481.It Ic character 482Disable the 483.Dv TELNET LINEMODE 484option, or, if the remote side does not understand the 485.Dv LINEMODE 486option, then enter \*(Lqcharacter at a time\*(Lq mode. 487.It Ic line 488Enable the 489.Dv TELNET LINEMODE 490option, or, if the remote side does not understand the 491.Dv LINEMODE 492option, then attempt to enter \*(Lqold-line-by-line\*(Lq mode. 493.It Ic isig Pq Ic \-isig 494Attempt to enable (disable) the 495.Dv TRAPSIG 496mode of the 497.Dv LINEMODE 498option. 499This requires that the 500.Dv LINEMODE 501option be enabled. 502.It Ic edit Pq Ic \-edit 503Attempt to enable (disable) the 504.Dv EDIT 505mode of the 506.Dv LINEMODE 507option. 508This requires that the 509.Dv LINEMODE 510option be enabled. 511.It Ic softtabs Pq Ic \-softtabs 512Attempt to enable (disable) the 513.Dv SOFT_TAB 514mode of the 515.Dv LINEMODE 516option. 517This requires that the 518.Dv LINEMODE 519option be enabled. 520.It Ic litecho Pq Ic \-litecho 521Attempt to enable (disable) the 522.Dv LIT_ECHO 523mode of the 524.Dv LINEMODE 525option. 526This requires that the 527.Dv LINEMODE 528option be enabled. 529.It Ic ?\& 530Prints out help information for the 531.Ic mode 532command. 533.El 534.It Xo 535.Ic open Ar host 536.Op Fl l Ar user 537.Op Oo Fl Oc Ns Ar port 538.Xc 539Open a connection to the named host. 540If no port number 541is specified, 542.Nm telnet 543will attempt to contact a 544.Tn TELNET 545server at the default port. 546The host specification may be either a host name (see 547.Xr hosts 5 ) 548or an Internet address specified in the \*(Lqdot notation\*(Rq (see 549.Xr inet 3 ) . 550The 551.Op Fl l 552option may be used to specify the user name 553to be passed to the remote system via the 554.Ev ENVIRON 555option. 556When connecting to a non-standard port, 557.Nm telnet 558omits any automatic initiation of 559.Tn TELNET 560options. When the port number is preceded by a minus sign, 561the initial option negotiation is done. 562After establishing a connection, the file 563.Pa \&.telnetrc 564in the 565users home directory is opened. Lines beginning with a # are 566comment lines. Blank lines are ignored. Lines that begin 567without white space are the start of a machine entry. The 568first thing on the line is the name of the machine that is 569being connected to. The rest of the line, and successive 570lines that begin with white space are assumed to be 571.Nm telnet 572commands and are processed as if they had been typed 573in manually to the 574.Nm telnet 575command prompt. 576.It Ic quit 577Close any open 578.Tn TELNET 579session and exit 580.Nm telnet . 581An end of file (in command mode) will also close a session and exit. 582.It Ic send Ar arguments 583Sends one or more special character sequences to the remote host. 584The following are the arguments which may be specified 585(more than one argument may be specified at a time): 586.Pp 587.Bl -tag -width escape 588.It Ic abort 589Sends the 590.Dv TELNET ABORT 591(Abort 592processes) 593sequence. 594.It Ic ao 595Sends the 596.Dv TELNET AO 597(Abort Output) sequence, which should cause the remote system to flush 598all output 599.Em from 600the remote system 601.Em to 602the user's terminal. 603.It Ic ayt 604Sends the 605.Dv TELNET AYT 606(Are You There) 607sequence, to which the remote system may or may not choose to respond. 608.It Ic brk 609Sends the 610.Dv TELNET BRK 611(Break) sequence, which may have significance to the remote 612system. 613.It Ic ec 614Sends the 615.Dv TELNET EC 616(Erase Character) 617sequence, which should cause the remote system to erase the last character 618entered. 619.It Ic el 620Sends the 621.Dv TELNET EL 622(Erase Line) 623sequence, which should cause the remote system to erase the line currently 624being entered. 625.It Ic eof 626Sends the 627.Dv TELNET EOF 628(End Of File) 629sequence. 630.It Ic eor 631Sends the 632.Dv TELNET EOR 633(End of Record) 634sequence. 635.It Ic escape 636Sends the current 637.Nm telnet 638escape character (initially \*(Lq^\*(Rq). 639.It Ic ga 640Sends the 641.Dv TELNET GA 642(Go Ahead) 643sequence, which likely has no significance to the remote system. 644.It Ic getstatus 645If the remote side supports the 646.Dv TELNET STATUS 647command, 648.Ic getstatus 649will send the subnegotiation to request that the server send 650its current option status. 651.It Ic ip 652Sends the 653.Dv TELNET IP 654(Interrupt Process) sequence, which should cause the remote 655system to abort the currently running process. 656.It Ic nop 657Sends the 658.Dv TELNET NOP 659(No OPeration) 660sequence. 661.It Ic susp 662Sends the 663.Dv TELNET SUSP 664(SUSPend process) 665sequence. 666.It Ic synch 667Sends the 668.Dv TELNET SYNCH 669sequence. 670This sequence causes the remote system to discard all previously typed 671(but not yet read) input. 672This sequence is sent as 673.Tn TCP 674urgent 675data (and may not work if the remote system is a 676.Bx 4.2 677system -- if 678it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal). 679.It Ic do Ar cmd 680.It Ic dont Ar cmd 681.It Ic will Ar cmd 682.It Ic wont Ar cmd 683Sends the 684.Dv TELNET DO 685.Ar cmd 686sequence. 687.Ar Cmd 688can be either a decimal number between 0 and 255, 689or a symbolic name for a specific 690.Dv TELNET 691command. 692.Ar Cmd 693can also be either 694.Ic help 695or 696.Ic ?\& 697to print out help information, including 698a list of known symbolic names. 699.It Ic ?\& 700Prints out help information for the 701.Ic send 702command. 703.El 704.It Ic set Ar argument value 705.It Ic unset Ar argument value 706The 707.Ic set 708command will set any one of a number of 709.Nm telnet 710variables to a specific value or to 711.Dv TRUE . 712The special value 713.Ic off 714turns off the function associated with 715the variable, this is equivalent to using the 716.Ic unset 717command. 718The 719.Ic unset 720command will disable or set to 721.Dv FALSE 722any of the specified functions. 723The values of variables may be interrogated with the 724.Ic display 725command. 726The variables which may be set or unset, but not toggled, are 727listed here. In addition, any of the variables for the 728.Ic toggle 729command may be explicitly set or unset using 730the 731.Ic set 732and 733.Ic unset 734commands. 735.Bl -tag -width escape 736.It Ic ayt 737If 738.Tn TELNET 739is in localchars mode, or 740.Dv LINEMODE 741is enabled, and the status character is typed, a 742.Dv TELNET AYT 743sequence (see 744.Ic send ayt 745preceding) is sent to the 746remote host. The initial value for the "Are You There" 747character is the terminal's status character. 748.It Ic echo 749This is the value (initially \*(Lq^E\*(Rq) which, when in 750\*(Lqline by line\*(Rq mode, toggles between doing local echoing 751of entered characters (for normal processing), and suppressing 752echoing of entered characters (for entering, say, a password). 753.It Ic eof 754If 755.Nm telnet 756is operating in 757.Dv LINEMODE 758or \*(Lqold line by line\*(Rq mode, entering this character 759as the first character on a line will cause this character to be 760sent to the remote system. 761The initial value of the eof character is taken to be the terminal's 762.Ic eof 763character. 764.It Ic erase 765If 766.Nm telnet 767is in 768.Ic localchars 769mode (see 770.Ic toggle 771.Ic localchars 772below), 773.Sy and 774if 775.Nm telnet 776is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 777character is typed, a 778.Dv TELNET EC 779sequence (see 780.Ic send 781.Ic ec 782above) 783is sent to the remote system. 784The initial value for the erase character is taken to be 785the terminal's 786.Ic erase 787character. 788.It Ic escape 789This is the 790.Nm telnet 791escape character (initially \*(Lq^[\*(Rq) which causes entry 792into 793.Nm telnet 794command mode (when connected to a remote system). 795.It Ic flushoutput 796If 797.Nm telnet 798is in 799.Ic localchars 800mode (see 801.Ic toggle 802.Ic localchars 803below) 804and the 805.Ic flushoutput 806character is typed, a 807.Dv TELNET AO 808sequence (see 809.Ic send 810.Ic ao 811above) 812is sent to the remote host. 813The initial value for the flush character is taken to be 814the terminal's 815.Ic flush 816character. 817.It Ic forw1 818.It Ic forw2 819If 820.Tn TELNET 821is operating in 822.Dv LINEMODE , 823these are the 824characters that, when typed, cause partial lines to be 825forwarded to the remote system. The initial value for 826the forwarding characters are taken from the terminal's 827eol and eol2 characters. 828.It Ic interrupt 829If 830.Nm telnet 831is in 832.Ic localchars 833mode (see 834.Ic toggle 835.Ic localchars 836below) 837and the 838.Ic interrupt 839character is typed, a 840.Dv TELNET IP 841sequence (see 842.Ic send 843.Ic ip 844above) 845is sent to the remote host. 846The initial value for the interrupt character is taken to be 847the terminal's 848.Ic intr 849character. 850.It Ic kill 851If 852.Nm telnet 853is in 854.Ic localchars 855mode (see 856.Ic toggle 857.Ic localchars 858below), 859.Ic and 860if 861.Nm telnet 862is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 863character is typed, a 864.Dv TELNET EL 865sequence (see 866.Ic send 867.Ic el 868above) 869is sent to the remote system. 870The initial value for the kill character is taken to be 871the terminal's 872.Ic kill 873character. 874.It Ic lnext 875If 876.Nm telnet 877is operating in 878.Dv LINEMODE 879or \*(Lqold line by line\*(Lq mode, then this character is taken to 880be the terminal's 881.Ic lnext 882character. 883The initial value for the lnext character is taken to be 884the terminal's 885.Ic lnext 886character. 887.It Ic quit 888If 889.Nm telnet 890is in 891.Ic localchars 892mode (see 893.Ic toggle 894.Ic localchars 895below) 896and the 897.Ic quit 898character is typed, a 899.Dv TELNET BRK 900sequence (see 901.Ic send 902.Ic brk 903above) 904is sent to the remote host. 905The initial value for the quit character is taken to be 906the terminal's 907.Ic quit 908character. 909.It Ic reprint 910If 911.Nm telnet 912is operating in 913.Dv LINEMODE 914or \*(Lqold line by line\*(Lq mode, then this character is taken to 915be the terminal's 916.Ic reprint 917character. 918The initial value for the reprint character is taken to be 919the terminal's 920.Ic reprint 921character. 922.It Ic rlogin 923This is the rlogin escape character. 924If set, the normal 925.Tn TELNET 926escape character is ignored unless it is 927preceded by this character at the beginning of a line. 928This character, at the beginning of a line followed by 929a "." closes the connection; when followed by a ^Z it 930suspends the telnet command. The initial state is to 931disable the rlogin escape character. 932.It Ic start 933If the 934.Dv TELNET TOGGLE-FLOW-CONTROL 935option has been enabled, 936then this character is taken to 937be the terminal's 938.Ic start 939character. 940The initial value for the kill character is taken to be 941the terminal's 942.Ic start 943character. 944.It Ic stop 945If the 946.Dv TELNET TOGGLE-FLOW-CONTROL 947option has been enabled, 948then this character is taken to 949be the terminal's 950.Ic stop 951character. 952The initial value for the kill character is taken to be 953the terminal's 954.Ic stop 955character. 956.It Ic susp 957If 958.Nm telnet 959is in 960.Ic localchars 961mode, or 962.Dv LINEMODE 963is enabled, and the 964.Ic suspend 965character is typed, a 966.Dv TELNET SUSP 967sequence (see 968.Ic send 969.Ic susp 970above) 971is sent to the remote host. 972The initial value for the suspend character is taken to be 973the terminal's 974.Ic suspend 975character. 976.It Ic tracefile 977This is the file to which the output, caused by 978.Ic netdata 979or 980.Ic option 981tracing being 982.Dv TRUE , 983will be written. If it is set to 984.Dq Fl , 985then tracing information will be written to standard output (the default). 986.It Ic worderase 987If 988.Nm telnet 989is operating in 990.Dv LINEMODE 991or \*(Lqold line by line\*(Lq mode, then this character is taken to 992be the terminal's 993.Ic worderase 994character. 995The initial value for the worderase character is taken to be 996the terminal's 997.Ic worderase 998character. 999.It Ic ?\& 1000Displays the legal 1001.Ic set 1002.Pq Ic unset 1003commands. 1004.El 1005.It Ic slc Ar state 1006The 1007.Ic slc 1008command (Set Local Characters) is used to set 1009or change the state of the the special 1010characters when the 1011.Dv TELNET LINEMODE 1012option has 1013been enabled. Special characters are characters that get 1014mapped to 1015.Tn TELNET 1016commands sequences (like 1017.Ic ip 1018or 1019.Ic quit ) 1020or line editing characters (like 1021.Ic erase 1022and 1023.Ic kill ) . 1024By default, the local special characters are exported. 1025.Bl -tag -width Fl 1026.It Ic check 1027Verify the current settings for the current special characters. 1028The remote side is requested to send all the current special 1029character settings, and if there are any discrepancies with 1030the local side, the local side will switch to the remote value. 1031.It Ic export 1032Switch to the local defaults for the special characters. The 1033local default characters are those of the local terminal at 1034the time when 1035.Nm telnet 1036was started. 1037.It Ic import 1038Switch to the remote defaults for the special characters. 1039The remote default characters are those of the remote system 1040at the time when the 1041.Tn TELNET 1042connection was established. 1043.It Ic ?\& 1044Prints out help information for the 1045.Ic slc 1046command. 1047.El 1048.It Ic status 1049Show the current status of 1050.Nm telnet . 1051This includes the peer one is connected to, as well 1052as the current mode. 1053.It Ic toggle Ar arguments ... 1054Toggle (between 1055.Dv TRUE 1056and 1057.Dv FALSE ) 1058various flags that control how 1059.Nm telnet 1060responds to events. 1061These flags may be set explicitly to 1062.Dv TRUE 1063or 1064.Dv FALSE 1065using the 1066.Ic set 1067and 1068.Ic unset 1069commands listed above. 1070More than one argument may be specified. 1071The state of these flags may be interrogated with the 1072.Ic display 1073command. 1074Valid arguments are: 1075.Bl -tag -width Ar 1076.It Ic authdebug 1077Turns on debugging information for the authentication code. 1078.It Ic autoflush 1079If 1080.Ic autoflush 1081and 1082.Ic localchars 1083are both 1084.Dv TRUE , 1085then when the 1086.Ic ao , 1087or 1088.Ic quit 1089characters are recognized (and transformed into 1090.Tn TELNET 1091sequences; see 1092.Ic set 1093above for details), 1094.Nm telnet 1095refuses to display any data on the user's terminal 1096until the remote system acknowledges (via a 1097.Dv TELNET TIMING MARK 1098option) 1099that it has processed those 1100.Tn TELNET 1101sequences. 1102The initial value for this toggle is 1103.Dv TRUE 1104if the terminal user had not 1105done an "stty noflsh", otherwise 1106.Dv FALSE 1107(see 1108.Xr stty 1 ) . 1109.It Ic autodecrypt 1110When the 1111.Dv TELNET ENCRYPT 1112option is negotiated, by 1113default the actual encryption (decryption) of the data 1114stream does not start automatically. The autoencrypt 1115(autodecrypt) command states that encryption of the 1116output (input) stream should be enabled as soon as 1117possible. 1118.Pp 1119Note: Because of export controls, the 1120.Dv TELNET ENCRYPT 1121option is not supported outside the United States and Canada. 1122.It Ic autologin 1123If the remote side supports the 1124.Dv TELNET AUTHENTICATION 1125option 1126.Tn TELNET 1127attempts to use it to perform automatic authentication. If the 1128.Dv AUTHENTICATION 1129option is not supported, the user's login 1130name are propagated through the 1131.Dv TELNET ENVIRON 1132option. 1133This command is the same as specifying 1134.Ar a 1135option on the 1136.Ic open 1137command. 1138.It Ic autosynch 1139If 1140.Ic autosynch 1141and 1142.Ic localchars 1143are both 1144.Dv TRUE , 1145then when either the 1146.Ic intr 1147or 1148.Ic quit 1149characters is typed (see 1150.Ic set 1151above for descriptions of the 1152.Ic intr 1153and 1154.Ic quit 1155characters), the resulting 1156.Tn TELNET 1157sequence sent is followed by the 1158.Dv TELNET SYNCH 1159sequence. 1160This procedure 1161.Ic should 1162cause the remote system to begin throwing away all previously 1163typed input until both of the 1164.Tn TELNET 1165sequences have been read and acted upon. 1166The initial value of this toggle is 1167.Dv FALSE . 1168.It Ic binary 1169Enable or disable the 1170.Dv TELNET BINARY 1171option on both input and output. 1172.It Ic inbinary 1173Enable or disable the 1174.Dv TELNET BINARY 1175option on input. 1176.It Ic outbinary 1177Enable or disable the 1178.Dv TELNET BINARY 1179option on output. 1180.It Ic crlf 1181If this is 1182.Dv TRUE , 1183then carriage returns will be sent as 1184.Li \*[Lt]CR\*[Gt]\*[Lt]LF\*[Gt] . 1185If this is 1186.Dv FALSE , 1187then carriage returns will be send as 1188.Li \*[Lt]CR\*[Gt]\*[Lt]NUL\*[Gt] . 1189The initial value for this toggle is 1190.Dv FALSE . 1191.It Ic crmod 1192Toggle carriage return mode. 1193When this mode is enabled, most carriage return characters received from 1194the remote host will be mapped into a carriage return followed by 1195a line feed. 1196This mode does not affect those characters typed by the user, only 1197those received from the remote host. 1198This mode is not very useful unless the remote host 1199only sends carriage return, but never line feed. 1200The initial value for this toggle is 1201.Dv FALSE . 1202.It Ic debug 1203Toggles socket level debugging (useful only to the 1204.Ic super user ) . 1205The initial value for this toggle is 1206.Dv FALSE . 1207.It Ic encdebug 1208Turns on debugging information for the encryption code. 1209.It Ic localchars 1210If this is 1211.Dv TRUE , 1212then the 1213.Ic flush , 1214.Ic interrupt , 1215.Ic quit , 1216.Ic erase , 1217and 1218.Ic kill 1219characters (see 1220.Ic set 1221above) are recognized locally, and transformed into (hopefully) appropriate 1222.Tn TELNET 1223control sequences 1224(respectively 1225.Ic ao , 1226.Ic ip , 1227.Ic brk , 1228.Ic ec , 1229and 1230.Ic el ; 1231see 1232.Ic send 1233above). 1234The initial value for this toggle is 1235.Dv TRUE 1236in \*(Lqold line by line\*(Rq mode, 1237and 1238.Dv FALSE 1239in \*(Lqcharacter at a time\*(Rq mode. 1240When the 1241.Dv LINEMODE 1242option is enabled, the value of 1243.Ic localchars 1244is ignored, and assumed to always be 1245.Dv TRUE . 1246If 1247.Dv LINEMODE 1248has ever been enabled, then 1249.Ic quit 1250is sent as 1251.Ic abort , 1252and 1253.Ic eof 1254and 1255.Ic suspend 1256are sent as 1257.Ic eof 1258and 1259.Ic susp , 1260see 1261.Ic send 1262above). 1263.It Ic netdata 1264Toggles the display of all network data (in hexadecimal format). 1265The initial value for this toggle is 1266.Dv FALSE . 1267.It Ic options 1268Toggles the display of some internal 1269.Nm telnet 1270protocol processing (having to do with 1271.Tn TELNET 1272options). 1273The initial value for this toggle is 1274.Dv FALSE . 1275.It Ic prettydump 1276When the 1277.Ic netdata 1278toggle is enabled, if 1279.Ic prettydump 1280is enabled the output from the 1281.Ic netdata 1282command will be formatted in a more user readable format. 1283Spaces are put between each character in the output, and the 1284beginning of any 1285.Tn TELNET 1286escape sequence is preceded by a '*' to aid in locating them. 1287.It Ic skiprc 1288When the skiprc toggle is 1289.Dv TRUE , 1290.Tn TELNET 1291skips the reading of the 1292.Pa \&.telnetrc 1293file in the users home 1294directory when connections are opened. The initial 1295value for this toggle is 1296.Dv FALSE . 1297.It Ic termdata 1298Toggles the display of all terminal data (in hexadecimal format). 1299The initial value for this toggle is 1300.Dv FALSE . 1301.It Ic verbose_encrypt 1302When the 1303.Ic verbose_encrypt 1304toggle is 1305.Dv TRUE , 1306.Tn TELNET 1307prints out a message each time encryption is enabled or 1308disabled. The initial value for this toggle is 1309.Dv FALSE . 1310Note: Because of export controls, data encryption 1311is not supported outside of the United States and Canada. 1312.It Ic \&? 1313Displays the legal 1314.Ic toggle 1315commands. 1316.El 1317.It Ic z 1318Suspend 1319.Nm telnet . 1320This command only works when the user is using the 1321.Xr csh 1 . 1322.It Ic \&! Op Ar command 1323Execute a single command in a subshell on the local 1324system. If 1325.Ic command 1326is omitted, then an interactive 1327subshell is invoked. 1328.It Ic ?\& Op Ar command 1329Get help. With no arguments, 1330.Nm telnet 1331prints a help summary. 1332If a command is specified, 1333.Nm telnet 1334will print the help information for just that command. 1335.El 1336.Sh ENVIRONMENT 1337.Nm Telnet 1338uses at least the 1339.Ev HOME , 1340.Ev SHELL , 1341.Ev DISPLAY , 1342and 1343.Ev TERM 1344environment variables. 1345Other environment variables may be propagated 1346to the other side via the 1347.Dv TELNET ENVIRON 1348option. 1349.Sh FILES 1350.Bl -tag -width ~/.telnetrc -compact 1351.It Pa ~/.telnetrc 1352user customized telnet startup values 1353.El 1354.Sh HISTORY 1355The 1356.Nm Telnet 1357command appeared in 1358.Bx 4.2 . 1359.Sh NOTES 1360.Pp 1361On some remote systems, echo has to be turned off manually when in 1362\*(Lqold line by line\*(Rq mode. 1363.Pp 1364In \*(Lqold line by line\*(Rq mode or 1365.Dv LINEMODE 1366the terminal's 1367.Ic eof 1368character is only recognized (and sent to the remote system) 1369when it is the first character on a line. 1370