1.\" $NetBSD: telnet.1,v 1.31 2009/03/11 13:58:58 joerg 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 4 43.Op Fl 6 44.Op Fl 8 45.Op Fl E 46.Op Fl F 47.Op Fl K 48.Op Fl L 49.Op Fl N 50.Bk -words 51.Op Fl S Ar tos 52.Ek 53.Bk -words 54.Op Fl X Ar authtype 55.Ek 56.Op Fl a 57.Op Fl c 58.Op Fl d 59.Bk -words 60.Op Fl e Ar escapechar 61.Ek 62.Op Fl f 63.Bk -words 64.Op Fl k Ar realm 65.Ek 66.Bk -words 67.Op Fl l Ar user 68.Ek 69.Bk -words 70.Op Fl n Ar tracefile 71.Ek 72.Bk -words 73.Op Fl P Ar policy 74.Ek 75.Op Fl r 76.Op Fl x 77.Oo 78.Ar host 79.Op Ar port 80.Oc 81.Sh DESCRIPTION 82The 83.Nm 84command 85is used to communicate with another host using the 86.Tn TELNET 87protocol. 88If 89.Nm 90is invoked without the 91.Ar host 92argument, it enters command mode, 93indicated by its prompt 94.Pq Nm telnet\&\*[Gt] . 95In this mode, it accepts and executes the commands listed below. 96If it is invoked with arguments, it performs an 97.Ic open 98command with those arguments. 99.Pp 100Options: 101.Bl -tag -width indent 102.It Fl 4 103Forces 104.Nm 105to use IPv4 addresses only. 106.It Fl 6 107Forces 108.Nm 109to use IPv6 addresses only. 110.It Fl 8 111Specifies an 8-bit data path. 112This causes an attempt to 113negotiate the 114.Dv TELNET BINARY 115option on both input and output. 116.It Fl E 117Stops any character from being recognized as an escape character. 118.It Fl F 119If Kerberos V5 authentication is being used, the 120.Fl F 121option allows the local credentials to be forwarded 122to the remote system, including any credentials that 123have already been forwarded into the local environment. 124.It Fl K 125Specifies no automatic login to the remote system. 126.It Fl L 127Specifies an 8-bit data path on output. 128This causes the 129BINARY option to be negotiated on output. 130.It Fl N 131Numeric host address. 132No attempt will be made to look up 133symbolic names for host addresses. 134.It Fl S Ar tos 135Sets the IP type-of-service (TOS) option for the telnet 136connection to the value 137.Ar tos , 138which can be a numeric TOS value 139or, on systems that support it, a symbolic 140TOS name found in the /etc/iptos file. 141.It Fl X Ar atype 142Disables the 143.Ar atype 144type of authentication. 145.It Fl a 146Attempt automatic login. 147Currently, this sends the user name via the 148.Ev USER 149variable 150of the 151.Ev ENVIRON 152option if supported by the remote system. 153The name used is that of the current user as returned by 154.Xr getlogin 2 155if it agrees with the current user ID, 156otherwise it is the name associated with the user ID. 157.It Fl c 158Disables the reading of the user's 159.Pa \&.telnetrc 160file. 161(See the 162.Ic toggle skiprc 163command on this man page.) 164.It Fl d 165Sets the initial value of the 166.Ic debug 167toggle to 168.Dv TRUE . 169.It Fl e Ar escape char 170Sets the initial 171.Nm 172escape character to 173.Ar escape char . 174If 175.Ar escape char 176is omitted, then 177there will be no escape character. 178.It Fl f 179If Kerberos V5 authentication is being used, the 180.Fl f 181option allows the local credentials to be forwarded to the remote system. 182.It Fl k Ar realm 183If Kerberos authentication is being used, the 184.Fl k 185option requests that telnet obtain tickets for the remote host in 186realm 187.Ar realm 188instead of the remote host's realm, as determined by 189.Xr krb_realmofhost 3 . 190.It Fl l Ar user 191When connecting to the remote system, if the remote system 192understands the 193.Ev ENVIRON 194option, then 195.Ar user 196will be sent to the remote system as the value for the variable USER. 197This option implies the 198.Fl a 199option. 200This option may also be used with the 201.Ic open 202command. 203.It Fl n Ar tracefile 204Opens 205.Ar tracefile 206for recording trace information. 207See the 208.Ic set tracefile 209command below. 210.It Fl P Ar policy 211Use IPsec policy specification string 212.Ar policy , 213for the connections. 214See 215.Xr ipsec_set_policy 3 216for details. 217.It Fl r 218Specifies a user interface similar to 219.Xr rlogin 1 . 220In this 221mode, the escape character is set to the tilde (~) character, 222unless modified by the 223.Fl e 224option. 225.It Fl x 226Turns on encryption of the data stream if possible. 227This 228option is not available outside of the United States and 229Canada. 230.It Ar host 231Indicates the official name, an alias, or the Internet address 232of a remote host. 233.It Ar port 234Indicates a port number (address of an application). 235If a number is 236not specified, the default 237.Nm 238port is used. 239.El 240.Pp 241When in rlogin mode, a line of the form ~. 242disconnects from the 243remote host; ~ is the telnet escape character. 244Similarly, the line ~^Z suspends the telnet session. 245The line ~^] escapes to the normal telnet escape prompt. 246.Pp 247Once a connection has been opened, 248.Nm 249will attempt to enable the 250.Dv TELNET LINEMODE 251option. 252If this fails, then 253.Nm 254will revert to one of two input modes: 255either \*(Lqcharacter at a time\*(Rq 256or \*(Lqold line by line\*(Rq 257depending on what the remote system supports. 258.Pp 259When 260.Dv LINEMODE 261is enabled, character processing is done on the 262local system, under the control of the remote system. 263When input 264editing or character echoing is to be disabled, the remote system 265will relay that information. 266The remote system will also relay 267changes to any special characters that happen on the remote 268system, so that they can take effect on the local system. 269.Pp 270In \*(Lqcharacter at a time\*(Rq mode, most 271text typed is immediately sent to the remote host for processing. 272.Pp 273In \*(Lqold line by line\*(Rq mode, all text is echoed locally, 274and (normally) only completed lines are sent to the remote host. 275The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used 276to turn off and on the local echo 277(this would mostly be used to enter passwords 278without the password being echoed). 279.Pp 280If the 281.Dv LINEMODE 282option is enabled, or if the 283.Ic localchars 284toggle is 285.Dv TRUE 286(the default for \*(Lqold line by line\*(Lq; see below), 287the user's 288.Ic quit , 289.Ic intr , 290and 291.Ic flush 292characters are trapped locally, and sent as 293.Tn TELNET 294protocol sequences to the remote side. 295If 296.Dv LINEMODE 297has ever been enabled, then the user's 298.Ic susp 299and 300.Ic eof 301are also sent as 302.Tn TELNET 303protocol sequences, 304and 305.Ic quit 306is sent as a 307.Dv TELNET ABORT 308instead of 309.Dv BREAK . 310There are options (see 311.Ic toggle 312.Ic autoflush 313and 314.Ic toggle 315.Ic autosynch 316below) 317which cause this action to flush subsequent output to the terminal 318(until the remote host acknowledges the 319.Tn TELNET 320sequence) and flush previous terminal input 321(in the case of 322.Ic quit 323and 324.Ic intr ) . 325.Pp 326While connected to a remote host, 327.Nm 328command mode may be entered by typing the 329.Nm 330\*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq). 331When in command mode, the normal terminal editing conventions are available. 332.Pp 333The following 334.Nm 335commands are available. 336Only enough of each command to uniquely identify it need be typed 337(this is also true for arguments to the 338.Ic mode , 339.Ic set , 340.Ic toggle , 341.Ic unset , 342.Ic slc , 343.Ic environ , 344and 345.Ic display 346commands). 347.Pp 348.Bl -tag -width "mode type" 349.It Ic auth Ar argument ... 350The auth command manipulates the information sent through the 351.Dv TELNET AUTHENTICATE 352option. 353Valid arguments for the 354auth command are as follows: 355.Bl -tag -width "disable type" 356.It Ic disable Ar type 357Disables the specified type of authentication. 358To obtain a list of available types, use the 359.Ic auth disable \&? 360command. 361.It Ic enable Ar type 362Enables the specified type of authentication. 363To obtain a list of available types, use the 364.Ic auth enable \&? 365command. 366.It Ic status 367Lists the current status of the various types of 368authentication. 369.El 370.It Ic close 371Close a 372.Tn TELNET 373session and return to command mode. 374.It Ic display Ar argument ... 375Displays all, or some, of the 376.Ic set 377and 378.Ic toggle 379values (see below). 380.It Ic encrypt Ar argument ... 381The encrypt command manipulates the information sent through the 382.Dv TELNET ENCRYPT 383option. 384.Pp 385Note: Because of export controls, the 386.Dv TELNET ENCRYPT 387option is not supported outside of the United States and Canada. 388.Pp 389Valid arguments for the encrypt command are: 390.Bl -tag -width Ar 391.It Ic disable Ar type Ic [input|output] 392Disables the specified type of encryption. 393If you omit the input and output, both input and output 394are disabled. 395To obtain a list of available types, use the 396.Ic encrypt disable \&? 397command. 398.It Ic enable Ar type Ic [input|output] 399Enables the specified type of encryption. 400If you omit input and output, both input and output are 401enabled. 402To obtain a list of available types, use the 403.Ic encrypt enable \&? 404command. 405.It Ic input 406This is the same as the 407.Ic encrypt start input 408command. 409.It Ic -input 410This is the same as the 411.Ic encrypt stop input 412command. 413.It Ic output 414This is the same as the 415.Ic encrypt start output 416command. 417.It Ic -output 418This is the same as the 419.Ic encrypt stop output 420command. 421.It Ic start Ic [input|output] 422Attempts to start encryption. 423If you omit 424.Ic input 425and 426.Ic output , 427both input and output are enabled. 428To obtain a list of available types, use the 429.Ic encrypt enable \&? 430command. 431.It Ic status 432Lists the current status of encryption. 433.It Ic stop Ic [input|output] 434Stops encryption. 435If you omit input and output, 436encryption is on both input and output. 437.It Ic type Ar type 438Sets the default type of encryption to be used 439with later 440.Ic encrypt start 441or 442.Ic encrypt stop 443commands. 444.El 445.It Ic environ Ar arguments ... 446The 447.Ic environ 448command is used to manipulate the 449variables that may be sent through the 450.Dv TELNET ENVIRON 451option. 452The initial set of variables is taken from the users 453environment, with only the 454.Ev DISPLAY 455and 456.Ev PRINTER 457variables being exported by default. 458The 459.Ev USER 460variable is also exported if the 461.Fl a 462or 463.Fl l 464options are used. 465.Pp 466Valid arguments for the 467.Ic environ 468command are: 469.Bl -tag -width Fl 470.It Ic define Ar variable value 471Define the variable 472.Ar variable 473to have a value of 474.Ar value . 475Any variables defined by this command are automatically exported. 476The 477.Ar value 478may be enclosed in single or double quotes so 479that tabs and spaces may be included. 480.It Ic undefine Ar variable 481Remove 482.Ar variable 483from the list of environment variables. 484.It Ic export Ar variable 485Mark the variable 486.Ar variable 487to be exported to the remote side. 488.It Ic unexport Ar variable 489Mark the variable 490.Ar variable 491to not be exported unless 492explicitly asked for by the remote side. 493.It Ic list 494List the current set of environment variables. 495Those marked with a 496.Cm * 497will be sent automatically, 498other variables will only be sent if explicitly requested. 499.It Ic \&? 500Prints out help information for the 501.Ic environ 502command. 503.El 504.It Ic logout 505Sends the 506.Dv TELNET LOGOUT 507option to the remote side. 508This command is similar to a 509.Ic close 510command; however, if the remote side does not support the 511.Dv LOGOUT 512option, nothing happens. 513If, however, the remote side does support the 514.Dv LOGOUT 515option, this command should cause the remote side to close the 516.Tn TELNET 517connection. 518If the remote side also supports the concept of 519suspending a user's session for later reattachment, 520the logout argument indicates that you 521should terminate the session immediately. 522.It Ic mode Ar type 523.Ar Type 524is one of several options, depending on the state of the 525.Tn TELNET 526session. 527The remote host is asked for permission to go into the requested mode. 528If the remote host is capable of entering that mode, the requested 529mode will be entered. 530.Bl -tag -width Ar 531.It Ic character 532Disable the 533.Dv TELNET LINEMODE 534option, or, if the remote side does not understand the 535.Dv LINEMODE 536option, then enter \*(Lqcharacter at a time\*(Lq mode. 537.It Ic line 538Enable the 539.Dv TELNET LINEMODE 540option, or, if the remote side does not understand the 541.Dv LINEMODE 542option, then attempt to enter \*(Lqold-line-by-line\*(Lq mode. 543.It Ic isig Pq Ic \-isig 544Attempt to enable (disable) the 545.Dv TRAPSIG 546mode of the 547.Dv LINEMODE 548option. 549This requires that the 550.Dv LINEMODE 551option be enabled. 552.It Ic edit Pq Ic \-edit 553Attempt to enable (disable) the 554.Dv EDIT 555mode of the 556.Dv LINEMODE 557option. 558This requires that the 559.Dv LINEMODE 560option be enabled. 561.It Ic softtabs Pq Ic \-softtabs 562Attempt to enable (disable) the 563.Dv SOFT_TAB 564mode of the 565.Dv LINEMODE 566option. 567This requires that the 568.Dv LINEMODE 569option be enabled. 570.It Ic litecho Pq Ic \-litecho 571Attempt to enable (disable) the 572.Dv LIT_ECHO 573mode of the 574.Dv LINEMODE 575option. 576This requires that the 577.Dv LINEMODE 578option be enabled. 579.It Ic \&? 580Prints out help information for the 581.Ic mode 582command. 583.El 584.It Ic open Ar host Oo Fl l Ar user Oc Oo Fl a Oc Oo Oo \&- Oc Ns Ar port Oc 585Open a connection to the named host. 586If no port number 587is specified, 588.Nm 589will attempt to contact a 590.Tn TELNET 591server at the default port. 592The host specification may be either a host name (see 593.Xr hosts 5 ) 594or an Internet address specified in the \*(Lqdot notation\*(Rq (see 595.Xr inet 3 ) . 596The 597.Fl l 598option may be used to specify the user name 599to be passed to the remote system via the 600.Ev ENVIRON 601option. 602If a port is specified 603.Nm 604omits any automatic initialisation of 605.Tn TELNET 606options. 607When the port number is preceded by a minus sign, 608the initial option negotiation is done. 609.Pp 610After establishing a connection, the file 611.Pa \&.telnetrc 612in the 613user's home directory is read. 614Lines beginning with a # are 615comment lines. 616Blank lines are ignored. 617Lines that begin 618without white space are the start of a machine entry. 619The first thing on such a line is a string identifying the machine 620that is being connected to. 621It may be the hostname or numeric address specified as the argument 622.Ar host , 623the canonical name of that string as determined by 624.Xr getaddrinfo 3 , 625or the string 626.Dq DEFAULT 627indicating all hosts. 628The rest of the line, and successive 629lines that begin with white space are assumed to be 630.Nm 631commands and are processed as if they had been typed 632in manually to the 633.Nm 634command prompt. 635.It Ic quit 636Close any open 637.Tn TELNET 638session and exit 639.Nm . 640An end of file (in command mode) will also close a session and exit. 641.It Ic send Ar arguments 642Sends one or more special character sequences to the remote host. 643The following are the arguments which may be specified 644(more than one argument may be specified at a time): 645.Pp 646.Bl -tag -width escape 647.It Ic abort 648Sends the 649.Dv TELNET ABORT 650(Abort 651processes) 652sequence. 653.It Ic ao 654Sends the 655.Dv TELNET AO 656(Abort Output) sequence, which should cause the remote system to flush 657all output 658.Em from 659the remote system 660.Em to 661the user's terminal. 662.It Ic ayt 663Sends the 664.Dv TELNET AYT 665(Are You There) 666sequence, to which the remote system may or may not choose to respond. 667.It Ic brk 668Sends the 669.Dv TELNET BRK 670(Break) sequence, which may have significance to the remote 671system. 672.It Ic ec 673Sends the 674.Dv TELNET EC 675(Erase Character) 676sequence, which should cause the remote system to erase the last character 677entered. 678.It Ic el 679Sends the 680.Dv TELNET EL 681(Erase Line) 682sequence, which should cause the remote system to erase the line currently 683being entered. 684.It Ic eof 685Sends the 686.Dv TELNET EOF 687(End Of File) 688sequence. 689.It Ic eor 690Sends the 691.Dv TELNET EOR 692(End of Record) 693sequence. 694.It Ic escape 695Sends the current 696.Nm 697escape character (initially \*(Lq^\*(Rq). 698.It Ic ga 699Sends the 700.Dv TELNET GA 701(Go Ahead) 702sequence, which likely has no significance to the remote system. 703.It Ic getstatus 704If the remote side supports the 705.Dv TELNET STATUS 706command, 707.Ic getstatus 708will send the subnegotiation to request that the server send 709its current option status. 710.It Ic ip 711Sends the 712.Dv TELNET IP 713(Interrupt Process) sequence, which should cause the remote 714system to abort the currently running process. 715.It Ic nop 716Sends the 717.Dv TELNET NOP 718(No OPeration) 719sequence. 720.It Ic susp 721Sends the 722.Dv TELNET SUSP 723(SUSPend process) 724sequence. 725.It Ic synch 726Sends the 727.Dv TELNET SYNCH 728sequence. 729This sequence causes the remote system to discard all previously typed 730(but not yet read) input. 731This sequence is sent as 732.Tn TCP 733urgent 734data (and may not work if the remote system is a 735.Bx 4.2 736system -- if 737it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal). 738.It Ic do Ar cmd 739.It Ic dont Ar cmd 740.It Ic will Ar cmd 741.It Ic wont Ar cmd 742Sends the 743.Dv TELNET DO 744.Ar cmd 745sequence. 746.Ar Cmd 747can be either a decimal number between 0 and 255, 748or a symbolic name for a specific 749.Dv TELNET 750command. 751.Ar Cmd 752can also be either 753.Ic help 754or 755.Ic \&? 756to print out help information, including 757a list of known symbolic names. 758.It Ic \&? 759Prints out help information for the 760.Ic send 761command. 762.El 763.It Ic set Ar argument value 764.It Ic unset Ar argument value 765The 766.Ic set 767command will set any one of a number of 768.Nm 769variables to a specific value or to 770.Dv TRUE . 771The special value 772.Ic off 773turns off the function associated with 774the variable, this is equivalent to using the 775.Ic unset 776command. 777The 778.Ic unset 779command will disable or set to 780.Dv FALSE 781any of the specified functions. 782The values of variables may be interrogated with the 783.Ic display 784command. 785The variables which may be set or unset, but not toggled, are 786listed here. 787In addition, any of the variables for the 788.Ic toggle 789command may be explicitly set or unset using 790the 791.Ic set 792and 793.Ic unset 794commands. 795.Bl -tag -width escape 796.It Ic ayt 797If 798.Tn TELNET 799is in localchars mode, or 800.Dv LINEMODE 801is enabled, and the status character is typed, a 802.Dv TELNET AYT 803sequence (see 804.Ic send ayt 805above) is sent to the 806remote host. 807The initial value for the "Are You There" 808character is the terminal's status character. 809.It Ic echo 810This is the value (initially \*(Lq^E\*(Rq) which, when in 811\*(Lqline by line\*(Rq mode, toggles between doing local echoing 812of entered characters (for normal processing), and suppressing 813echoing of entered characters (for entering, say, a password). 814.It Ic eof 815If 816.Nm 817is operating in 818.Dv LINEMODE 819or \*(Lqold line by line\*(Rq mode, entering this character 820as the first character on a line will cause this character to be 821sent to the remote system. 822The initial value of the eof character is taken to be the terminal's 823.Ic eof 824character. 825.It Ic erase 826If 827.Nm 828is in 829.Ic localchars 830mode (see 831.Ic toggle 832.Ic localchars 833below), 834.Sy and 835if 836.Nm 837is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 838character is typed, a 839.Dv TELNET EC 840sequence (see 841.Ic send 842.Ic ec 843above) 844is sent to the remote system. 845The initial value for the erase character is taken to be 846the terminal's 847.Ic erase 848character. 849.It Ic escape 850This is the 851.Nm 852escape character (initially \*(Lq^[\*(Rq) which causes entry 853into 854.Nm 855command mode (when connected to a remote system). 856.It Ic flushoutput 857If 858.Nm 859is in 860.Ic localchars 861mode (see 862.Ic toggle 863.Ic localchars 864below) 865and the 866.Ic flushoutput 867character is typed, a 868.Dv TELNET AO 869sequence (see 870.Ic send 871.Ic ao 872above) 873is sent to the remote host. 874The initial value for the flush character is taken to be 875the terminal's 876.Ic flush 877character. 878.It Ic forw1 879.It Ic forw2 880If 881.Tn TELNET 882is operating in 883.Dv LINEMODE , 884these are the 885characters that, when typed, cause partial lines to be 886forwarded to the remote system. 887The initial value for 888the forwarding characters are taken from the terminal's 889eol and eol2 characters. 890.It Ic interrupt 891If 892.Nm 893is in 894.Ic localchars 895mode (see 896.Ic toggle 897.Ic localchars 898below) 899and the 900.Ic interrupt 901character is typed, a 902.Dv TELNET IP 903sequence (see 904.Ic send 905.Ic ip 906above) 907is sent to the remote host. 908The initial value for the interrupt character is taken to be 909the terminal's 910.Ic intr 911character. 912.It Ic kill 913If 914.Nm 915is in 916.Ic localchars 917mode (see 918.Ic toggle 919.Ic localchars 920below), 921.Ic and 922if 923.Nm 924is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 925character is typed, a 926.Dv TELNET EL 927sequence (see 928.Ic send 929.Ic el 930above) 931is sent to the remote system. 932The initial value for the kill character is taken to be 933the terminal's 934.Ic kill 935character. 936.It Ic lnext 937If 938.Nm 939is operating in 940.Dv LINEMODE 941or \*(Lqold line by line\*(Lq mode, then this character is taken to 942be the terminal's 943.Ic lnext 944character. 945The initial value for the lnext character is taken to be 946the terminal's 947.Ic lnext 948character. 949.It Ic quit 950If 951.Nm 952is in 953.Ic localchars 954mode (see 955.Ic toggle 956.Ic localchars 957below) 958and the 959.Ic quit 960character is typed, a 961.Dv TELNET BRK 962sequence (see 963.Ic send 964.Ic brk 965above) 966is sent to the remote host. 967The initial value for the quit character is taken to be 968the terminal's 969.Ic quit 970character. 971.It Ic reprint 972If 973.Nm 974is operating in 975.Dv LINEMODE 976or \*(Lqold line by line\*(Lq mode, then this character is taken to 977be the terminal's 978.Ic reprint 979character. 980The initial value for the reprint character is taken to be 981the terminal's 982.Ic reprint 983character. 984.It Ic rlogin 985This is the rlogin escape character. 986If set, the normal 987.Tn TELNET 988escape character is ignored unless it is 989preceded by this character at the beginning of a line. 990This character, at the beginning of a line followed by 991a "." closes the connection; when followed by a ^Z it 992suspends the 993.Nm 994command. 995The initial state is to 996disable the rlogin escape character. 997.It Ic start 998If the 999.Dv TELNET TOGGLE-FLOW-CONTROL 1000option has been enabled, 1001then this character is taken to 1002be the terminal's 1003.Ic start 1004character. 1005The initial value for the start character is taken to be 1006the terminal's 1007.Ic start 1008character. 1009.It Ic stop 1010If the 1011.Dv TELNET TOGGLE-FLOW-CONTROL 1012option has been enabled, 1013then this character is taken to 1014be the terminal's 1015.Ic stop 1016character. 1017The initial value for the stop character is taken to be 1018the terminal's 1019.Ic stop 1020character. 1021.It Ic susp 1022If 1023.Nm 1024is in 1025.Ic localchars 1026mode, or 1027.Dv LINEMODE 1028is enabled, and the 1029.Ic suspend 1030character is typed, a 1031.Dv TELNET SUSP 1032sequence (see 1033.Ic send 1034.Ic susp 1035above) 1036is sent to the remote host. 1037The initial value for the suspend character is taken to be 1038the terminal's 1039.Ic suspend 1040character. 1041.It Ic tracefile 1042This is the file to which the output, caused by 1043.Ic netdata 1044or 1045.Ic option 1046tracing being 1047.Dv TRUE , 1048will be written. 1049If it is set to 1050.Dq Fl , 1051then tracing information will be written to standard output (the default). 1052.It Ic worderase 1053If 1054.Nm 1055is operating in 1056.Dv LINEMODE 1057or \*(Lqold line by line\*(Lq mode, then this character is taken to 1058be the terminal's 1059.Ic worderase 1060character. 1061The initial value for the worderase character is taken to be 1062the terminal's 1063.Ic worderase 1064character. 1065.It Ic \&? 1066Displays the legal 1067.Ic set 1068.Pq Ic unset 1069commands. 1070.El 1071.It Ic slc Ar state 1072The 1073.Ic slc 1074command (Set Local Characters) is used to set 1075or change the state of the special 1076characters when the 1077.Dv TELNET LINEMODE 1078option has 1079been enabled. 1080Special characters are characters that get 1081mapped to 1082.Tn TELNET 1083commands sequences (like 1084.Ic ip 1085or 1086.Ic quit ) 1087or line editing characters (like 1088.Ic erase 1089and 1090.Ic kill ) . 1091By default, the local special characters are exported. 1092.Bl -tag -width Fl 1093.It Ic check 1094Verify the current settings for the current special characters. 1095The remote side is requested to send all the current special 1096character settings, and if there are any discrepancies with 1097the local side, the local side will switch to the remote value. 1098.It Ic export 1099Switch to the local defaults for the special characters. 1100The 1101local default characters are those of the local terminal at 1102the time when 1103.Nm 1104was started. 1105.It Ic import 1106Switch to the remote defaults for the special characters. 1107The remote default characters are those of the remote system 1108at the time when the 1109.Tn TELNET 1110connection was established. 1111.It Ic \&? 1112Prints out help information for the 1113.Ic slc 1114command. 1115.El 1116.It Ic status 1117Show the current status of 1118.Nm . 1119This includes the peer one is connected to, as well 1120as the current mode. 1121.It Ic toggle Ar arguments ... 1122Toggle (between 1123.Dv TRUE 1124and 1125.Dv FALSE ) 1126various flags that control how 1127.Nm 1128responds to events. 1129These flags may be set explicitly to 1130.Dv TRUE 1131or 1132.Dv FALSE 1133using the 1134.Ic set 1135and 1136.Ic unset 1137commands listed above. 1138More than one argument may be specified. 1139The state of these flags may be interrogated with the 1140.Ic display 1141command. 1142Valid arguments are: 1143.Bl -tag -width Ar 1144.It Ic authdebug 1145Turns on debugging information for the authentication code. 1146.It Ic autoflush 1147If 1148.Ic autoflush 1149and 1150.Ic localchars 1151are both 1152.Dv TRUE , 1153then when the 1154.Ic ao , 1155or 1156.Ic quit 1157characters are recognized (and transformed into 1158.Tn TELNET 1159sequences; see 1160.Ic set 1161above for details), 1162.Nm 1163refuses to display any data on the user's terminal 1164until the remote system acknowledges (via a 1165.Dv TELNET TIMING MARK 1166option) 1167that it has processed those 1168.Tn TELNET 1169sequences. 1170The initial value for this toggle is 1171.Dv TRUE 1172if the terminal user had not 1173done an "stty noflsh", otherwise 1174.Dv FALSE 1175(see 1176.Xr stty 1 ) . 1177.It Ic autodecrypt 1178When the 1179.Dv TELNET ENCRYPT 1180option is negotiated, by 1181default the actual encryption (decryption) of the data 1182stream does not start automatically. 1183The autoencrypt 1184(autodecrypt) command states that encryption of the 1185output (input) stream should be enabled as soon as 1186possible. 1187.Pp 1188Note: Because of export controls, the 1189.Dv TELNET ENCRYPT 1190option is not supported outside the United States and Canada. 1191.It Ic autologin 1192If the remote side supports the 1193.Dv TELNET AUTHENTICATION 1194option 1195.Tn TELNET 1196attempts to use it to perform automatic authentication. 1197If the 1198.Dv AUTHENTICATION 1199option is not supported, the user's login 1200name are propagated through the 1201.Dv TELNET ENVIRON 1202option. 1203This command is the same as specifying the 1204.Fl a 1205option on the 1206.Ic open 1207command. 1208.It Ic autosynch 1209If 1210.Ic autosynch 1211and 1212.Ic localchars 1213are both 1214.Dv TRUE , 1215then when either the 1216.Ic intr 1217or 1218.Ic quit 1219characters is typed (see 1220.Ic set 1221above for descriptions of the 1222.Ic intr 1223and 1224.Ic quit 1225characters), the resulting 1226.Tn TELNET 1227sequence sent is followed by the 1228.Dv TELNET SYNCH 1229sequence. 1230This procedure 1231.Ic should 1232cause the remote system to begin throwing away all previously 1233typed input until both of the 1234.Tn TELNET 1235sequences have been read and acted upon. 1236The initial value of this toggle is 1237.Dv FALSE . 1238.It Ic binary 1239Enable or disable the 1240.Dv TELNET BINARY 1241option on both input and output. 1242.It Ic inbinary 1243Enable or disable the 1244.Dv TELNET BINARY 1245option on input. 1246.It Ic outbinary 1247Enable or disable the 1248.Dv TELNET BINARY 1249option on output. 1250.It Ic crlf 1251If this is 1252.Dv TRUE , 1253then carriage returns will be sent as 1254.Li \*[Lt]CR\*[Gt]\*[Lt]LF\*[Gt] . 1255If this is 1256.Dv FALSE , 1257then carriage returns will be send as 1258.Li \*[Lt]CR\*[Gt]\*[Lt]NUL\*[Gt] . 1259The initial value for this toggle is 1260.Dv FALSE . 1261.It Ic crmod 1262Toggle carriage return mode. 1263When this mode is enabled, most carriage return characters received from 1264the remote host will be mapped into a carriage return followed by 1265a line feed. 1266This mode does not affect those characters typed by the user, only 1267those received from the remote host. 1268This mode is not very useful unless the remote host 1269only sends carriage return, but never line feed. 1270The initial value for this toggle is 1271.Dv FALSE . 1272.It Ic debug 1273Toggles socket level debugging (useful only to the 1274.Ic super user ) . 1275The initial value for this toggle is 1276.Dv FALSE . 1277.It Ic encdebug 1278Turns on debugging information for the encryption code. 1279.It Ic localchars 1280If this is 1281.Dv TRUE , 1282then the 1283.Ic flush , 1284.Ic interrupt , 1285.Ic quit , 1286.Ic erase , 1287and 1288.Ic kill 1289characters (see 1290.Ic set 1291above) are recognized locally, and transformed into (hopefully) appropriate 1292.Tn TELNET 1293control sequences 1294(respectively 1295.Ic ao , 1296.Ic ip , 1297.Ic brk , 1298.Ic ec , 1299and 1300.Ic el ; 1301see 1302.Ic send 1303above). 1304The initial value for this toggle is 1305.Dv TRUE 1306in \*(Lqold line by line\*(Rq mode, 1307and 1308.Dv FALSE 1309in \*(Lqcharacter at a time\*(Rq mode. 1310When the 1311.Dv LINEMODE 1312option is enabled, the value of 1313.Ic localchars 1314is ignored, and assumed to always be 1315.Dv TRUE . 1316If 1317.Dv LINEMODE 1318has ever been enabled, then 1319.Ic quit 1320is sent as 1321.Ic abort , 1322and 1323.Ic eof and 1324.Ic suspend 1325are sent as 1326.Ic eof and 1327.Ic susp 1328(see 1329.Ic send 1330above). 1331.It Ic netdata 1332Toggles the display of all network data (in hexadecimal format). 1333The initial value for this toggle is 1334.Dv FALSE . 1335.It Ic options 1336Toggles the display of some internal 1337.Nm 1338protocol processing (having to do with 1339.Tn TELNET 1340options). 1341The initial value for this toggle is 1342.Dv FALSE . 1343.It Ic prettydump 1344When the 1345.Ic netdata 1346toggle is enabled, if 1347.Ic prettydump 1348is enabled the output from the 1349.Ic netdata 1350command will be formatted in a more user readable format. 1351Spaces are put between each character in the output, and the 1352beginning of any 1353.Tn TELNET 1354escape sequence is preceded by a '*' to aid in locating them. 1355.It Ic skiprc 1356When the skiprc toggle is 1357.Dv TRUE , 1358.Tn TELNET 1359skips the reading of the 1360.Pa \&.telnetrc 1361file in the users home 1362directory when connections are opened. 1363The initial 1364value for this toggle is 1365.Dv FALSE . 1366.It Ic termdata 1367Toggles the display of all terminal data (in hexadecimal format). 1368The initial value for this toggle is 1369.Dv FALSE . 1370.It Ic verbose_encrypt 1371When the 1372.Ic verbose_encrypt 1373toggle is 1374.Dv TRUE , 1375.Nm 1376prints out a message each time encryption is enabled or 1377disabled. 1378The initial value for this toggle is 1379.Dv FALSE . 1380Note: Because of export controls, data encryption 1381is not supported outside of the United States and Canada. 1382.It Ic \&? 1383Displays the legal 1384.Ic toggle 1385commands. 1386.El 1387.It Ic z 1388Suspend 1389.Nm . 1390This command only works when the user is using the 1391.Xr csh 1 . 1392.It Ic \&! Op Ar command 1393Execute a single command in a subshell on the local 1394system. 1395If 1396.Ar command 1397is omitted, then an interactive 1398subshell is invoked. 1399.It Ic \&? Op Ar command 1400Get help. 1401With no arguments, 1402.Nm 1403prints a help summary. 1404If a command is specified, 1405.Nm 1406will print the help information for just that command. 1407.El 1408.Sh ENVIRONMENT 1409.Nm 1410uses at least the 1411.Ev HOME , 1412.Ev SHELL , 1413.Ev DISPLAY , 1414and 1415.Ev TERM 1416environment variables. 1417Other environment variables may be propagated 1418to the other side via the 1419.Dv TELNET ENVIRON 1420option. 1421.Sh FILES 1422.Bl -tag -width ~/.telnetrc -compact 1423.It Pa ~/.telnetrc 1424user customized telnet startup values 1425.El 1426.Sh HISTORY 1427The 1428.Nm 1429command appeared in 1430.Bx 4.2 . 1431IPsec support was added by WIDE/KAME project, in 1999. 1432.Sh NOTES 1433On some remote systems, echo has to be turned off manually when in 1434\*(Lqold line by line\*(Rq mode. 1435.Pp 1436In \*(Lqold line by line\*(Rq mode or 1437.Dv LINEMODE 1438the terminal's 1439.Ic eof 1440character is only recognized (and sent to the remote system) 1441when it is the first character on a line. 1442