1.\" $NetBSD: telnet.1,v 1.33 2012/04/08 22:00:39 wiz Exp $ 2.\" 3.\" Copyright (c) 1983, 1990, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" from: @(#)telnet.1 8.4 (Berkeley) 2/3/94 31.\" 32.Dd October 28, 2003 33.Dt TELNET 1 34.Os 35.Sh NAME 36.Nm telnet 37.Nd user interface to the 38.Tn TELNET 39protocol 40.Sh SYNOPSIS 41.Nm 42.Op Fl 468acdEFfKLNrx 43.Op Fl e Ar escapechar 44.Op Fl k Ar realm 45.Op Fl l Ar user 46.Op Fl n Ar tracefile 47.Op Fl P Ar policy 48.Op Fl S Ar tos 49.Op Fl X Ar authtype 50.Oo 51.Ar host 52.Op Ar port 53.Oc 54.Sh DESCRIPTION 55The 56.Nm 57command 58is used to communicate with another host using the 59.Tn TELNET 60protocol. 61If 62.Nm 63is invoked without the 64.Ar host 65argument, it enters command mode, 66indicated by its prompt 67.Pq Nm telnet\&\*[Gt] . 68In this mode, it accepts and executes the commands listed below. 69If it is invoked with arguments, it performs an 70.Ic open 71command with those arguments. 72.Pp 73Options: 74.Bl -tag -width indent 75.It Fl 4 76Forces 77.Nm 78to use IPv4 addresses only. 79.It Fl 6 80Forces 81.Nm 82to use IPv6 addresses only. 83.It Fl 8 84Specifies an 8-bit data path. 85This causes an attempt to 86negotiate the 87.Dv TELNET BINARY 88option on both input and output. 89.It Fl E 90Stops any character from being recognized as an escape character. 91.It Fl F 92If Kerberos V5 authentication is being used, the 93.Fl F 94option allows the local credentials to be forwarded 95to the remote system, including any credentials that 96have already been forwarded into the local environment. 97.It Fl K 98Specifies no automatic login to the remote system. 99.It Fl L 100Specifies an 8-bit data path on output. 101This causes the 102BINARY option to be negotiated on output. 103.It Fl N 104Numeric host address. 105No attempt will be made to look up 106symbolic names for host addresses. 107.It Fl S Ar tos 108Sets the IP type-of-service (TOS) option for the telnet 109connection to the value 110.Ar tos , 111which can be a numeric TOS value 112or, on systems that support it, a symbolic 113TOS name found in the /etc/iptos file. 114.It Fl X Ar atype 115Disables the 116.Ar atype 117type of authentication. 118.It Fl a 119Attempt automatic login. 120Currently, this sends the user name via the 121.Ev USER 122variable 123of the 124.Ev ENVIRON 125option if supported by the remote system. 126The name used is that of the current user as returned by 127.Xr getlogin 2 128if it agrees with the current user ID, 129otherwise it is the name associated with the user ID. 130.It Fl c 131Disables the reading of the user's 132.Pa \&.telnetrc 133file. 134(See the 135.Ic toggle skiprc 136command on this man page.) 137.It Fl d 138Sets the initial value of the 139.Ic debug 140toggle to 141.Dv TRUE . 142.It Fl e Ar escape char 143Sets the initial 144.Nm 145escape character to 146.Ar escape char . 147If 148.Ar escape char 149is omitted, then 150there will be no escape character. 151.It Fl f 152If Kerberos V5 authentication is being used, the 153.Fl f 154option allows the local credentials to be forwarded to the remote system. 155.It Fl k Ar realm 156If Kerberos authentication is being used, the 157.Fl k 158option requests that telnet obtain tickets for the remote host in 159realm 160.Ar realm 161instead of the remote host's realm, as determined by 162.Xr krb_realmofhost 3 . 163.It Fl l Ar user 164When connecting to the remote system, if the remote system 165understands the 166.Ev ENVIRON 167option, then 168.Ar user 169will be sent to the remote system as the value for the variable USER. 170This option implies the 171.Fl a 172option. 173This option may also be used with the 174.Ic open 175command. 176.It Fl n Ar tracefile 177Opens 178.Ar tracefile 179for recording trace information. 180See the 181.Ic set tracefile 182command below. 183.It Fl P Ar policy 184Use IPsec policy specification string 185.Ar policy , 186for the connections. 187See 188.Xr ipsec_set_policy 3 189for details. 190.It Fl r 191Specifies a user interface similar to 192.Xr rlogin 1 . 193In this 194mode, the escape character is set to the tilde (~) character, 195unless modified by the 196.Fl e 197option. 198.It Fl x 199Turns on encryption of the data stream if possible. 200This 201option is not available outside of the United States and 202Canada. 203.It Ar host 204Indicates the official name, an alias, or the Internet address 205of a remote host. 206.It Ar port 207Indicates a port number (address of an application). 208If a number is 209not specified, the default 210.Nm 211port is used. 212.El 213.Pp 214When in rlogin mode, a line of the form ~. 215disconnects from the 216remote host; ~ is the telnet escape character. 217Similarly, the line ~^Z suspends the telnet session. 218The line ~^] escapes to the normal telnet escape prompt. 219.Pp 220Once a connection has been opened, 221.Nm 222will attempt to enable the 223.Dv TELNET LINEMODE 224option. 225If this fails, then 226.Nm 227will revert to one of two input modes: 228either \*(Lqcharacter at a time\*(Rq 229or \*(Lqold line by line\*(Rq 230depending on what the remote system supports. 231.Pp 232When 233.Dv LINEMODE 234is enabled, character processing is done on the 235local system, under the control of the remote system. 236When input 237editing or character echoing is to be disabled, the remote system 238will relay that information. 239The remote system will also relay 240changes to any special characters that happen on the remote 241system, so that they can take effect on the local system. 242.Pp 243In \*(Lqcharacter at a time\*(Rq mode, most 244text typed is immediately sent to the remote host for processing. 245.Pp 246In \*(Lqold line by line\*(Rq mode, all text is echoed locally, 247and (normally) only completed lines are sent to the remote host. 248The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used 249to turn off and on the local echo 250(this would mostly be used to enter passwords 251without the password being echoed). 252.Pp 253If the 254.Dv LINEMODE 255option is enabled, or if the 256.Ic localchars 257toggle is 258.Dv TRUE 259(the default for \*(Lqold line by line\*(Lq; see below), 260the user's 261.Ic quit , 262.Ic intr , 263and 264.Ic flush 265characters are trapped locally, and sent as 266.Tn TELNET 267protocol sequences to the remote side. 268If 269.Dv LINEMODE 270has ever been enabled, then the user's 271.Ic susp 272and 273.Ic eof 274are also sent as 275.Tn TELNET 276protocol sequences, 277and 278.Ic quit 279is sent as a 280.Dv TELNET ABORT 281instead of 282.Dv BREAK . 283There are options (see 284.Ic toggle 285.Ic autoflush 286and 287.Ic toggle 288.Ic autosynch 289below) 290which cause this action to flush subsequent output to the terminal 291(until the remote host acknowledges the 292.Tn TELNET 293sequence) and flush previous terminal input 294(in the case of 295.Ic quit 296and 297.Ic intr ) . 298.Pp 299While connected to a remote host, 300.Nm 301command mode may be entered by typing the 302.Nm 303\*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq). 304When in command mode, the normal terminal editing conventions are available. 305.Pp 306The following 307.Nm 308commands are available. 309Only enough of each command to uniquely identify it need be typed 310(this is also true for arguments to the 311.Ic mode , 312.Ic set , 313.Ic toggle , 314.Ic unset , 315.Ic slc , 316.Ic environ , 317and 318.Ic display 319commands). 320.Pp 321.Bl -tag -width "mode type" 322.It Ic auth Ar argument ... 323The auth command manipulates the information sent through the 324.Dv TELNET AUTHENTICATE 325option. 326Valid arguments for the 327auth command are as follows: 328.Bl -tag -width "disable type" 329.It Ic disable Ar type 330Disables the specified type of authentication. 331To obtain a list of available types, use the 332.Ic auth disable \&? 333command. 334.It Ic enable Ar type 335Enables the specified type of authentication. 336To obtain a list of available types, use the 337.Ic auth enable \&? 338command. 339.It Ic status 340Lists the current status of the various types of 341authentication. 342.El 343.It Ic close 344Close a 345.Tn TELNET 346session and return to command mode. 347.It Ic display Ar argument ... 348Displays all, or some, of the 349.Ic set 350and 351.Ic toggle 352values (see below). 353.It Ic encrypt Ar argument ... 354The encrypt command manipulates the information sent through the 355.Dv TELNET ENCRYPT 356option. 357.Pp 358Note: Because of export controls, the 359.Dv TELNET ENCRYPT 360option is not supported outside of the United States and Canada. 361.Pp 362Valid arguments for the encrypt command are: 363.Bl -tag -width Ar 364.It Ic disable Ar type Ic [input|output] 365Disables the specified type of encryption. 366If you omit the input and output, both input and output 367are disabled. 368To obtain a list of available types, use the 369.Ic encrypt disable \&? 370command. 371.It Ic enable Ar type Ic [input|output] 372Enables the specified type of encryption. 373If you omit input and output, both input and output are 374enabled. 375To obtain a list of available types, use the 376.Ic encrypt enable \&? 377command. 378.It Ic input 379This is the same as the 380.Ic encrypt start input 381command. 382.It Ic -input 383This is the same as the 384.Ic encrypt stop input 385command. 386.It Ic output 387This is the same as the 388.Ic encrypt start output 389command. 390.It Ic -output 391This is the same as the 392.Ic encrypt stop output 393command. 394.It Ic start Ic [input|output] 395Attempts to start encryption. 396If you omit 397.Ic input 398and 399.Ic output , 400both input and output are enabled. 401To obtain a list of available types, use the 402.Ic encrypt enable \&? 403command. 404.It Ic status 405Lists the current status of encryption. 406.It Ic stop Ic [input|output] 407Stops encryption. 408If you omit input and output, 409encryption is on both input and output. 410.It Ic type Ar type 411Sets the default type of encryption to be used 412with later 413.Ic encrypt start 414or 415.Ic encrypt stop 416commands. 417.El 418.It Ic environ Ar arguments ... 419The 420.Ic environ 421command is used to manipulate the 422variables that may be sent through the 423.Dv TELNET ENVIRON 424option. 425The initial set of variables is taken from the users 426environment, with only the 427.Ev DISPLAY 428and 429.Ev PRINTER 430variables being exported by default. 431The 432.Ev USER 433variable is also exported if the 434.Fl a 435or 436.Fl l 437options are used. 438.Pp 439Valid arguments for the 440.Ic environ 441command are: 442.Bl -tag -width Fl 443.It Ic define Ar variable value 444Define the variable 445.Ar variable 446to have a value of 447.Ar value . 448Any variables defined by this command are automatically exported. 449The 450.Ar value 451may be enclosed in single or double quotes so 452that tabs and spaces may be included. 453.It Ic undefine Ar variable 454Remove 455.Ar variable 456from the list of environment variables. 457.It Ic export Ar variable 458Mark the variable 459.Ar variable 460to be exported to the remote side. 461.It Ic unexport Ar variable 462Mark the variable 463.Ar variable 464to not be exported unless 465explicitly asked for by the remote side. 466.It Ic list 467List the current set of environment variables. 468Those marked with a 469.Cm * 470will be sent automatically, 471other variables will only be sent if explicitly requested. 472.It Ic \&? 473Prints out help information for the 474.Ic environ 475command. 476.El 477.It Ic logout 478Sends the 479.Dv TELNET LOGOUT 480option to the remote side. 481This command is similar to a 482.Ic close 483command; however, if the remote side does not support the 484.Dv LOGOUT 485option, nothing happens. 486If, however, the remote side does support the 487.Dv LOGOUT 488option, this command should cause the remote side to close the 489.Tn TELNET 490connection. 491If the remote side also supports the concept of 492suspending a user's session for later reattachment, 493the logout argument indicates that you 494should terminate the session immediately. 495.It Ic mode Ar type 496.Ar Type 497is one of several options, depending on the state of the 498.Tn TELNET 499session. 500The remote host is asked for permission to go into the requested mode. 501If the remote host is capable of entering that mode, the requested 502mode will be entered. 503.Bl -tag -width Ar 504.It Ic character 505Disable the 506.Dv TELNET LINEMODE 507option, or, if the remote side does not understand the 508.Dv LINEMODE 509option, then enter \*(Lqcharacter at a time\*(Lq mode. 510.It Ic line 511Enable the 512.Dv TELNET LINEMODE 513option, or, if the remote side does not understand the 514.Dv LINEMODE 515option, then attempt to enter \*(Lqold-line-by-line\*(Lq mode. 516.It Ic isig Pq Ic \-isig 517Attempt to enable (disable) the 518.Dv TRAPSIG 519mode of the 520.Dv LINEMODE 521option. 522This requires that the 523.Dv LINEMODE 524option be enabled. 525.It Ic edit Pq Ic \-edit 526Attempt to enable (disable) the 527.Dv EDIT 528mode of the 529.Dv LINEMODE 530option. 531This requires that the 532.Dv LINEMODE 533option be enabled. 534.It Ic softtabs Pq Ic \-softtabs 535Attempt to enable (disable) the 536.Dv SOFT_TAB 537mode of the 538.Dv LINEMODE 539option. 540This requires that the 541.Dv LINEMODE 542option be enabled. 543.It Ic litecho Pq Ic \-litecho 544Attempt to enable (disable) the 545.Dv LIT_ECHO 546mode of the 547.Dv LINEMODE 548option. 549This requires that the 550.Dv LINEMODE 551option be enabled. 552.It Ic \&? 553Prints out help information for the 554.Ic mode 555command. 556.El 557.It Ic open Ar host Oo Fl l Ar user Oc Oo Fl a Oc Oo Oo \&- Oc Ns Ar port Oc 558Open a connection to the named host. 559If no port number 560is specified, 561.Nm 562will attempt to contact a 563.Tn TELNET 564server at the default port. 565The host specification may be either a host name (see 566.Xr hosts 5 ) 567or an Internet address specified in the \*(Lqdot notation\*(Rq (see 568.Xr inet 3 ) . 569The 570.Fl l 571option may be used to specify the user name 572to be passed to the remote system via the 573.Ev ENVIRON 574option. 575If a port is specified 576.Nm 577omits any automatic initialisation of 578.Tn TELNET 579options. 580When the port number is preceded by a minus sign, 581the initial option negotiation is done. 582.Pp 583After establishing a connection, the file 584.Pa \&.telnetrc 585in the 586user's home directory is read. 587Lines beginning with a # are 588comment lines. 589Blank lines are ignored. 590Lines that begin 591without white space are the start of a machine entry. 592The first thing on such a line is a string identifying the machine 593that is being connected to. 594It may be the hostname or numeric address specified as the argument 595.Ar host , 596the canonical name of that string as determined by 597.Xr getaddrinfo 3 , 598or the string 599.Dq DEFAULT 600indicating all hosts. 601The rest of the line, and successive 602lines that begin with white space are assumed to be 603.Nm 604commands and are processed as if they had been typed 605in manually to the 606.Nm 607command prompt. 608.It Ic quit 609Close any open 610.Tn TELNET 611session and exit 612.Nm . 613An end of file (in command mode) will also close a session and exit. 614.It Ic send Ar arguments 615Sends one or more special character sequences to the remote host. 616The following are the arguments which may be specified 617(more than one argument may be specified at a time): 618.Pp 619.Bl -tag -width escape 620.It Ic abort 621Sends the 622.Dv TELNET ABORT 623(Abort 624processes) 625sequence. 626.It Ic ao 627Sends the 628.Dv TELNET AO 629(Abort Output) sequence, which should cause the remote system to flush 630all output 631.Em from 632the remote system 633.Em to 634the user's terminal. 635.It Ic ayt 636Sends the 637.Dv TELNET AYT 638(Are You There) 639sequence, to which the remote system may or may not choose to respond. 640.It Ic brk 641Sends the 642.Dv TELNET BRK 643(Break) sequence, which may have significance to the remote 644system. 645.It Ic ec 646Sends the 647.Dv TELNET EC 648(Erase Character) 649sequence, which should cause the remote system to erase the last character 650entered. 651.It Ic el 652Sends the 653.Dv TELNET EL 654(Erase Line) 655sequence, which should cause the remote system to erase the line currently 656being entered. 657.It Ic eof 658Sends the 659.Dv TELNET EOF 660(End Of File) 661sequence. 662.It Ic eor 663Sends the 664.Dv TELNET EOR 665(End of Record) 666sequence. 667.It Ic escape 668Sends the current 669.Nm 670escape character (initially \*(Lq^\*(Rq). 671.It Ic ga 672Sends the 673.Dv TELNET GA 674(Go Ahead) 675sequence, which likely has no significance to the remote system. 676.It Ic getstatus 677If the remote side supports the 678.Dv TELNET STATUS 679command, 680.Ic getstatus 681will send the subnegotiation to request that the server send 682its current option status. 683.It Ic ip 684Sends the 685.Dv TELNET IP 686(Interrupt Process) sequence, which should cause the remote 687system to abort the currently running process. 688.It Ic nop 689Sends the 690.Dv TELNET NOP 691(No OPeration) 692sequence. 693.It Ic susp 694Sends the 695.Dv TELNET SUSP 696(SUSPend process) 697sequence. 698.It Ic synch 699Sends the 700.Dv TELNET SYNCH 701sequence. 702This sequence causes the remote system to discard all previously typed 703(but not yet read) input. 704This sequence is sent as 705.Tn TCP 706urgent 707data (and may not work if the remote system is a 708.Bx 4.2 709system -- if 710it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal). 711.It Ic do Ar cmd 712.It Ic dont Ar cmd 713.It Ic will Ar cmd 714.It Ic wont Ar cmd 715Sends the 716.Dv TELNET DO 717.Ar cmd 718sequence. 719.Ar Cmd 720can be either a decimal number between 0 and 255, 721or a symbolic name for a specific 722.Dv TELNET 723command. 724.Ar Cmd 725can also be either 726.Ic help 727or 728.Ic \&? 729to print out help information, including 730a list of known symbolic names. 731.It Ic \&? 732Prints out help information for the 733.Ic send 734command. 735.El 736.It Ic set Ar argument value 737.It Ic unset Ar argument value 738The 739.Ic set 740command will set any one of a number of 741.Nm 742variables to a specific value or to 743.Dv TRUE . 744The special value 745.Ic off 746turns off the function associated with 747the variable, this is equivalent to using the 748.Ic unset 749command. 750The 751.Ic unset 752command will disable or set to 753.Dv FALSE 754any of the specified functions. 755The values of variables may be interrogated with the 756.Ic display 757command. 758The variables which may be set or unset, but not toggled, are 759listed here. 760In addition, any of the variables for the 761.Ic toggle 762command may be explicitly set or unset using 763the 764.Ic set 765and 766.Ic unset 767commands. 768.Bl -tag -width escape 769.It Ic ayt 770If 771.Tn TELNET 772is in localchars mode, or 773.Dv LINEMODE 774is enabled, and the status character is typed, a 775.Dv TELNET AYT 776sequence (see 777.Ic send ayt 778above) is sent to the 779remote host. 780The initial value for the "Are You There" 781character is the terminal's status character. 782.It Ic echo 783This is the value (initially \*(Lq^E\*(Rq) which, when in 784\*(Lqline by line\*(Rq mode, toggles between doing local echoing 785of entered characters (for normal processing), and suppressing 786echoing of entered characters (for entering, say, a password). 787.It Ic eof 788If 789.Nm 790is operating in 791.Dv LINEMODE 792or \*(Lqold line by line\*(Rq mode, entering this character 793as the first character on a line will cause this character to be 794sent to the remote system. 795The initial value of the eof character is taken to be the terminal's 796.Ic eof 797character. 798.It Ic erase 799If 800.Nm 801is in 802.Ic localchars 803mode (see 804.Ic toggle 805.Ic localchars 806below), 807.Sy and 808if 809.Nm 810is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 811character is typed, a 812.Dv TELNET EC 813sequence (see 814.Ic send 815.Ic ec 816above) 817is sent to the remote system. 818The initial value for the erase character is taken to be 819the terminal's 820.Ic erase 821character. 822.It Ic escape 823This is the 824.Nm 825escape character (initially \*(Lq^[\*(Rq) which causes entry 826into 827.Nm 828command mode (when connected to a remote system). 829.It Ic flushoutput 830If 831.Nm 832is in 833.Ic localchars 834mode (see 835.Ic toggle 836.Ic localchars 837below) 838and the 839.Ic flushoutput 840character is typed, a 841.Dv TELNET AO 842sequence (see 843.Ic send 844.Ic ao 845above) 846is sent to the remote host. 847The initial value for the flush character is taken to be 848the terminal's 849.Ic flush 850character. 851.It Ic forw1 852.It Ic forw2 853If 854.Tn TELNET 855is operating in 856.Dv LINEMODE , 857these are the 858characters that, when typed, cause partial lines to be 859forwarded to the remote system. 860The initial value for 861the forwarding characters are taken from the terminal's 862eol and eol2 characters. 863.It Ic interrupt 864If 865.Nm 866is in 867.Ic localchars 868mode (see 869.Ic toggle 870.Ic localchars 871below) 872and the 873.Ic interrupt 874character is typed, a 875.Dv TELNET IP 876sequence (see 877.Ic send 878.Ic ip 879above) 880is sent to the remote host. 881The initial value for the interrupt character is taken to be 882the terminal's 883.Ic intr 884character. 885.It Ic kill 886If 887.Nm 888is in 889.Ic localchars 890mode (see 891.Ic toggle 892.Ic localchars 893below), 894.Ic and 895if 896.Nm 897is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 898character is typed, a 899.Dv TELNET EL 900sequence (see 901.Ic send 902.Ic el 903above) 904is sent to the remote system. 905The initial value for the kill character is taken to be 906the terminal's 907.Ic kill 908character. 909.It Ic lnext 910If 911.Nm 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 lnext 917character. 918The initial value for the lnext character is taken to be 919the terminal's 920.Ic lnext 921character. 922.It Ic quit 923If 924.Nm 925is in 926.Ic localchars 927mode (see 928.Ic toggle 929.Ic localchars 930below) 931and the 932.Ic quit 933character is typed, a 934.Dv TELNET BRK 935sequence (see 936.Ic send 937.Ic brk 938above) 939is sent to the remote host. 940The initial value for the quit character is taken to be 941the terminal's 942.Ic quit 943character. 944.It Ic reprint 945If 946.Nm 947is operating in 948.Dv LINEMODE 949or \*(Lqold line by line\*(Lq mode, then this character is taken to 950be the terminal's 951.Ic reprint 952character. 953The initial value for the reprint character is taken to be 954the terminal's 955.Ic reprint 956character. 957.It Ic rlogin 958This is the rlogin escape character. 959If set, the normal 960.Tn TELNET 961escape character is ignored unless it is 962preceded by this character at the beginning of a line. 963This character, at the beginning of a line followed by 964a "." closes the connection; when followed by a ^Z it 965suspends the 966.Nm 967command. 968The initial state is to 969disable the rlogin escape character. 970.It Ic start 971If the 972.Dv TELNET TOGGLE-FLOW-CONTROL 973option has been enabled, 974then this character is taken to 975be the terminal's 976.Ic start 977character. 978The initial value for the start character is taken to be 979the terminal's 980.Ic start 981character. 982.It Ic stop 983If the 984.Dv TELNET TOGGLE-FLOW-CONTROL 985option has been enabled, 986then this character is taken to 987be the terminal's 988.Ic stop 989character. 990The initial value for the stop character is taken to be 991the terminal's 992.Ic stop 993character. 994.It Ic susp 995If 996.Nm 997is in 998.Ic localchars 999mode, or 1000.Dv LINEMODE 1001is enabled, and the 1002.Ic suspend 1003character is typed, a 1004.Dv TELNET SUSP 1005sequence (see 1006.Ic send 1007.Ic susp 1008above) 1009is sent to the remote host. 1010The initial value for the suspend character is taken to be 1011the terminal's 1012.Ic suspend 1013character. 1014.It Ic tracefile 1015This is the file to which the output, caused by 1016.Ic netdata 1017or 1018.Ic option 1019tracing being 1020.Dv TRUE , 1021will be written. 1022If it is set to 1023.Dq Fl , 1024then tracing information will be written to standard output (the default). 1025.It Ic worderase 1026If 1027.Nm 1028is operating in 1029.Dv LINEMODE 1030or \*(Lqold line by line\*(Lq mode, then this character is taken to 1031be the terminal's 1032.Ic worderase 1033character. 1034The initial value for the worderase character is taken to be 1035the terminal's 1036.Ic worderase 1037character. 1038.It Ic \&? 1039Displays the legal 1040.Ic set 1041.Pq Ic unset 1042commands. 1043.El 1044.It Ic slc Ar state 1045The 1046.Ic slc 1047command (Set Local Characters) is used to set 1048or change the state of the special 1049characters when the 1050.Dv TELNET LINEMODE 1051option has 1052been enabled. 1053Special characters are characters that get 1054mapped to 1055.Tn TELNET 1056commands sequences (like 1057.Ic ip 1058or 1059.Ic quit ) 1060or line editing characters (like 1061.Ic erase 1062and 1063.Ic kill ) . 1064By default, the local special characters are exported. 1065.Bl -tag -width Fl 1066.It Ic check 1067Verify the current settings for the current special characters. 1068The remote side is requested to send all the current special 1069character settings, and if there are any discrepancies with 1070the local side, the local side will switch to the remote value. 1071.It Ic export 1072Switch to the local defaults for the special characters. 1073The 1074local default characters are those of the local terminal at 1075the time when 1076.Nm 1077was started. 1078.It Ic import 1079Switch to the remote defaults for the special characters. 1080The remote default characters are those of the remote system 1081at the time when the 1082.Tn TELNET 1083connection was established. 1084.It Ic \&? 1085Prints out help information for the 1086.Ic slc 1087command. 1088.El 1089.It Ic status 1090Show the current status of 1091.Nm . 1092This includes the peer one is connected to, as well 1093as the current mode. 1094.It Ic toggle Ar arguments ... 1095Toggle (between 1096.Dv TRUE 1097and 1098.Dv FALSE ) 1099various flags that control how 1100.Nm 1101responds to events. 1102These flags may be set explicitly to 1103.Dv TRUE 1104or 1105.Dv FALSE 1106using the 1107.Ic set 1108and 1109.Ic unset 1110commands listed above. 1111More than one argument may be specified. 1112The state of these flags may be interrogated with the 1113.Ic display 1114command. 1115Valid arguments are: 1116.Bl -tag -width Ar 1117.It Ic authdebug 1118Turns on debugging information for the authentication code. 1119.It Ic autoflush 1120If 1121.Ic autoflush 1122and 1123.Ic localchars 1124are both 1125.Dv TRUE , 1126then when the 1127.Ic ao , 1128or 1129.Ic quit 1130characters are recognized (and transformed into 1131.Tn TELNET 1132sequences; see 1133.Ic set 1134above for details), 1135.Nm 1136refuses to display any data on the user's terminal 1137until the remote system acknowledges (via a 1138.Dv TELNET TIMING MARK 1139option) 1140that it has processed those 1141.Tn TELNET 1142sequences. 1143The initial value for this toggle is 1144.Dv TRUE 1145if the terminal user had not 1146done an "stty noflsh", otherwise 1147.Dv FALSE 1148(see 1149.Xr stty 1 ) . 1150.It Ic autodecrypt 1151When the 1152.Dv TELNET ENCRYPT 1153option is negotiated, by 1154default the actual encryption (decryption) of the data 1155stream does not start automatically. 1156The autoencrypt 1157(autodecrypt) command states that encryption of the 1158output (input) stream should be enabled as soon as 1159possible. 1160.Pp 1161Note: Because of export controls, the 1162.Dv TELNET ENCRYPT 1163option is not supported outside the United States and Canada. 1164.It Ic autologin 1165If the remote side supports the 1166.Dv TELNET AUTHENTICATION 1167option 1168.Tn TELNET 1169attempts to use it to perform automatic authentication. 1170If the 1171.Dv AUTHENTICATION 1172option is not supported, the user's login 1173name are propagated through the 1174.Dv TELNET ENVIRON 1175option. 1176This command is the same as specifying the 1177.Fl a 1178option on the 1179.Ic open 1180command. 1181.It Ic autosynch 1182If 1183.Ic autosynch 1184and 1185.Ic localchars 1186are both 1187.Dv TRUE , 1188then when either the 1189.Ic intr 1190or 1191.Ic quit 1192characters is typed (see 1193.Ic set 1194above for descriptions of the 1195.Ic intr 1196and 1197.Ic quit 1198characters), the resulting 1199.Tn TELNET 1200sequence sent is followed by the 1201.Dv TELNET SYNCH 1202sequence. 1203This procedure 1204.Ic should 1205cause the remote system to begin throwing away all previously 1206typed input until both of the 1207.Tn TELNET 1208sequences have been read and acted upon. 1209The initial value of this toggle is 1210.Dv FALSE . 1211.It Ic binary 1212Enable or disable the 1213.Dv TELNET BINARY 1214option on both input and output. 1215.It Ic inbinary 1216Enable or disable the 1217.Dv TELNET BINARY 1218option on input. 1219.It Ic outbinary 1220Enable or disable the 1221.Dv TELNET BINARY 1222option on output. 1223.It Ic crlf 1224If this is 1225.Dv TRUE , 1226then carriage returns will be sent as 1227.Li \*[Lt]CR\*[Gt]\*[Lt]LF\*[Gt] . 1228If this is 1229.Dv FALSE , 1230then carriage returns will be send as 1231.Li \*[Lt]CR\*[Gt]\*[Lt]NUL\*[Gt] . 1232The initial value for this toggle is 1233.Dv FALSE . 1234.It Ic crmod 1235Toggle carriage return mode. 1236When this mode is enabled, most carriage return characters received from 1237the remote host will be mapped into a carriage return followed by 1238a line feed. 1239This mode does not affect those characters typed by the user, only 1240those received from the remote host. 1241This mode is not very useful unless the remote host 1242only sends carriage return, but never line feed. 1243The initial value for this toggle is 1244.Dv FALSE . 1245.It Ic debug 1246Toggles socket level debugging (useful only to the 1247.Ic super user ) . 1248The initial value for this toggle is 1249.Dv FALSE . 1250.It Ic encdebug 1251Turns on debugging information for the encryption code. 1252.It Ic localchars 1253If this is 1254.Dv TRUE , 1255then the 1256.Ic flush , 1257.Ic interrupt , 1258.Ic quit , 1259.Ic erase , 1260and 1261.Ic kill 1262characters (see 1263.Ic set 1264above) are recognized locally, and transformed into (hopefully) appropriate 1265.Tn TELNET 1266control sequences 1267(respectively 1268.Ic ao , 1269.Ic ip , 1270.Ic brk , 1271.Ic ec , 1272and 1273.Ic el ; 1274see 1275.Ic send 1276above). 1277The initial value for this toggle is 1278.Dv TRUE 1279in \*(Lqold line by line\*(Rq mode, 1280and 1281.Dv FALSE 1282in \*(Lqcharacter at a time\*(Rq mode. 1283When the 1284.Dv LINEMODE 1285option is enabled, the value of 1286.Ic localchars 1287is ignored, and assumed to always be 1288.Dv TRUE . 1289If 1290.Dv LINEMODE 1291has ever been enabled, then 1292.Ic quit 1293is sent as 1294.Ic abort , 1295and 1296.Ic eof and 1297.Ic suspend 1298are sent as 1299.Ic eof and 1300.Ic susp 1301(see 1302.Ic send 1303above). 1304.It Ic netdata 1305Toggles the display of all network data (in hexadecimal format). 1306The initial value for this toggle is 1307.Dv FALSE . 1308.It Ic options 1309Toggles the display of some internal 1310.Nm 1311protocol processing (having to do with 1312.Tn TELNET 1313options). 1314The initial value for this toggle is 1315.Dv FALSE . 1316.It Ic prettydump 1317When the 1318.Ic netdata 1319toggle is enabled, if 1320.Ic prettydump 1321is enabled the output from the 1322.Ic netdata 1323command will be formatted in a more user readable format. 1324Spaces are put between each character in the output, and the 1325beginning of any 1326.Tn TELNET 1327escape sequence is preceded by a '*' to aid in locating them. 1328.It Ic skiprc 1329When the skiprc toggle is 1330.Dv TRUE , 1331.Tn TELNET 1332skips the reading of the 1333.Pa \&.telnetrc 1334file in the users home 1335directory when connections are opened. 1336The initial 1337value for this toggle is 1338.Dv FALSE . 1339.It Ic termdata 1340Toggles the display of all terminal data (in hexadecimal format). 1341The initial value for this toggle is 1342.Dv FALSE . 1343.It Ic verbose_encrypt 1344When the 1345.Ic verbose_encrypt 1346toggle is 1347.Dv TRUE , 1348.Nm 1349prints out a message each time encryption is enabled or 1350disabled. 1351The initial value for this toggle is 1352.Dv FALSE . 1353Note: Because of export controls, data encryption 1354is not supported outside of the United States and Canada. 1355.It Ic \&? 1356Displays the legal 1357.Ic toggle 1358commands. 1359.El 1360.It Ic z 1361Suspend 1362.Nm . 1363This command only works when the user is using the 1364.Xr csh 1 . 1365.It Ic \&! Op Ar command 1366Execute a single command in a subshell on the local 1367system. 1368If 1369.Ar command 1370is omitted, then an interactive 1371subshell is invoked. 1372.It Ic \&? Op Ar command 1373Get help. 1374With no arguments, 1375.Nm 1376prints a help summary. 1377If a command is specified, 1378.Nm 1379will print the help information for just that command. 1380.El 1381.Sh ENVIRONMENT 1382.Nm 1383uses at least the 1384.Ev HOME , 1385.Ev SHELL , 1386.Ev DISPLAY , 1387and 1388.Ev TERM 1389environment variables. 1390Other environment variables may be propagated 1391to the other side via the 1392.Dv TELNET ENVIRON 1393option. 1394.Sh FILES 1395.Bl -tag -width ~/.telnetrc -compact 1396.It Pa ~/.telnetrc 1397user customized telnet startup values 1398.El 1399.Sh HISTORY 1400The 1401.Nm 1402command appeared in 1403.Bx 4.2 . 1404IPsec support was added by WIDE/KAME project, in 1999. 1405.Sh NOTES 1406On some remote systems, echo has to be turned off manually when in 1407\*(Lqold line by line\*(Rq mode. 1408.Pp 1409In \*(Lqold line by line\*(Rq mode or 1410.Dv LINEMODE 1411the terminal's 1412.Ic eof 1413character is only recognized (and sent to the remote system) 1414when it is the first character on a line. 1415