1.\" $NetBSD: telnet.1,v 1.36 2018/12/15 22:17:02 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 December 16, 2018 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\&> . 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. 162.It Fl l Ar user 163When connecting to the remote system, if the remote system 164understands the 165.Ev ENVIRON 166option, then 167.Ar user 168will be sent to the remote system as the value for the variable USER. 169This option implies the 170.Fl a 171option. 172This option may also be used with the 173.Ic open 174command. 175.It Fl n Ar tracefile 176Opens 177.Ar tracefile 178for recording trace information. 179See the 180.Ic set tracefile 181command below. 182.It Fl P Ar policy 183Use IPsec policy specification string 184.Ar policy , 185for the connections. 186See 187.Xr ipsec_set_policy 3 188for details. 189.It Fl r 190Specifies a user interface similar to 191.Xr rlogin 1 . 192In this 193mode, the escape character is set to the tilde (~) character, 194unless modified by the 195.Fl e 196option. 197.It Fl x 198Turns on encryption of the data stream if possible. 199.It Ar host 200Indicates the official name, an alias, or the Internet address 201of a remote host. 202.It Ar port 203Indicates a port number (address of an application). 204If a number is 205not specified, the default 206.Nm 207port is used. 208.El 209.Pp 210When in rlogin mode, a line of the form ~. 211disconnects from the 212remote host; ~ is the telnet escape character. 213Similarly, the line ~^Z suspends the telnet session. 214The line ~^] escapes to the normal telnet escape prompt. 215.Pp 216Once a connection has been opened, 217.Nm 218will attempt to enable the 219.Dv TELNET LINEMODE 220option. 221If this fails, then 222.Nm 223will revert to one of two input modes: 224either \*(Lqcharacter at a time\*(Rq 225or \*(Lqold line by line\*(Rq 226depending on what the remote system supports. 227.Pp 228When 229.Dv LINEMODE 230is enabled, character processing is done on the 231local system, under the control of the remote system. 232When input 233editing or character echoing is to be disabled, the remote system 234will relay that information. 235The remote system will also relay 236changes to any special characters that happen on the remote 237system, so that they can take effect on the local system. 238.Pp 239In \*(Lqcharacter at a time\*(Rq mode, most 240text typed is immediately sent to the remote host for processing. 241.Pp 242In \*(Lqold line by line\*(Rq mode, all text is echoed locally, 243and (normally) only completed lines are sent to the remote host. 244The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used 245to turn off and on the local echo 246(this would mostly be used to enter passwords 247without the password being echoed). 248.Pp 249If the 250.Dv LINEMODE 251option is enabled, or if the 252.Ic localchars 253toggle is 254.Dv TRUE 255(the default for \*(Lqold line by line\*(Lq; see below), 256the user's 257.Ic quit , 258.Ic intr , 259and 260.Ic flush 261characters are trapped locally, and sent as 262.Tn TELNET 263protocol sequences to the remote side. 264If 265.Dv LINEMODE 266has ever been enabled, then the user's 267.Ic susp 268and 269.Ic eof 270are also sent as 271.Tn TELNET 272protocol sequences, 273and 274.Ic quit 275is sent as a 276.Dv TELNET ABORT 277instead of 278.Dv BREAK . 279There are options (see 280.Ic toggle 281.Ic autoflush 282and 283.Ic toggle 284.Ic autosynch 285below) 286which cause this action to flush subsequent output to the terminal 287(until the remote host acknowledges the 288.Tn TELNET 289sequence) and flush previous terminal input 290(in the case of 291.Ic quit 292and 293.Ic intr ) . 294.Pp 295While connected to a remote host, 296.Nm 297command mode may be entered by typing the 298.Nm 299\*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq). 300When in command mode, the normal terminal editing conventions are available. 301.Pp 302The following 303.Nm 304commands are available. 305Only enough of each command to uniquely identify it need be typed 306(this is also true for arguments to the 307.Ic mode , 308.Ic set , 309.Ic toggle , 310.Ic unset , 311.Ic slc , 312.Ic environ , 313and 314.Ic display 315commands). 316.Bl -tag -width "mode type" 317.It Ic auth Ar argument ... 318The auth command manipulates the information sent through the 319.Dv TELNET AUTHENTICATE 320option. 321Valid arguments for the 322auth command are as follows: 323.Bl -tag -width "disable type" 324.It Ic disable Ar type 325Disables the specified type of authentication. 326To obtain a list of available types, use the 327.Ic auth disable \&? 328command. 329.It Ic enable Ar type 330Enables the specified type of authentication. 331To obtain a list of available types, use the 332.Ic auth enable \&? 333command. 334.It Ic status 335Lists the current status of the various types of 336authentication. 337.El 338.It Ic close 339Close a 340.Tn TELNET 341session and return to command mode. 342.It Ic display Ar argument ... 343Displays all, or some, of the 344.Ic set 345and 346.Ic toggle 347values (see below). 348.It Ic encrypt Ar argument ... 349The encrypt command manipulates the information sent through the 350.Dv TELNET ENCRYPT 351option. 352.Pp 353Note: Because of export controls, the 354.Dv TELNET ENCRYPT 355option is not supported outside of the United States and Canada. 356.Pp 357Valid arguments for the encrypt command are: 358.Bl -tag -width Ar 359.It Ic disable Ar type Ic [input|output] 360Disables the specified type of encryption. 361If you omit the input and output, both input and output 362are disabled. 363To obtain a list of available types, use the 364.Ic encrypt disable \&? 365command. 366.It Ic enable Ar type Ic [input|output] 367Enables the specified type of encryption. 368If you omit input and output, both input and output are 369enabled. 370To obtain a list of available types, use the 371.Ic encrypt enable \&? 372command. 373.It Ic input 374This is the same as the 375.Ic encrypt start input 376command. 377.It Ic -input 378This is the same as the 379.Ic encrypt stop input 380command. 381.It Ic output 382This is the same as the 383.Ic encrypt start output 384command. 385.It Ic -output 386This is the same as the 387.Ic encrypt stop output 388command. 389.It Ic start Ic [input|output] 390Attempts to start encryption. 391If you omit 392.Ic input 393and 394.Ic output , 395both input and output are enabled. 396To obtain a list of available types, use the 397.Ic encrypt enable \&? 398command. 399.It Ic status 400Lists the current status of encryption. 401.It Ic stop Ic [input|output] 402Stops encryption. 403If you omit input and output, 404encryption is on both input and output. 405.It Ic type Ar type 406Sets the default type of encryption to be used 407with later 408.Ic encrypt start 409or 410.Ic encrypt stop 411commands. 412.El 413.It Ic environ Ar arguments ... 414The 415.Ic environ 416command is used to manipulate the 417variables that may be sent through the 418.Dv TELNET ENVIRON 419option. 420The initial set of variables is taken from the users 421environment, with only the 422.Ev DISPLAY 423and 424.Ev PRINTER 425variables being exported by default. 426The 427.Ev USER 428variable is also exported if the 429.Fl a 430or 431.Fl l 432options are used. 433.Pp 434Valid arguments for the 435.Ic environ 436command are: 437.Bl -tag -width Fl 438.It Ic define Ar variable value 439Define the variable 440.Ar variable 441to have a value of 442.Ar value . 443Any variables defined by this command are automatically exported. 444The 445.Ar value 446may be enclosed in single or double quotes so 447that tabs and spaces may be included. 448.It Ic undefine Ar variable 449Remove 450.Ar variable 451from the list of environment variables. 452.It Ic export Ar variable 453Mark the variable 454.Ar variable 455to be exported to the remote side. 456.It Ic unexport Ar variable 457Mark the variable 458.Ar variable 459to not be exported unless 460explicitly asked for by the remote side. 461.It Ic list 462List the current set of environment variables. 463Those marked with a 464.Cm * 465will be sent automatically, 466other variables will only be sent if explicitly requested. 467.It Ic \&? 468Prints out help information for the 469.Ic environ 470command. 471.El 472.It Ic logout 473Sends the 474.Dv TELNET LOGOUT 475option to the remote side. 476This command is similar to a 477.Ic close 478command; however, if the remote side does not support the 479.Dv LOGOUT 480option, nothing happens. 481If, however, the remote side does support the 482.Dv LOGOUT 483option, this command should cause the remote side to close the 484.Tn TELNET 485connection. 486If the remote side also supports the concept of 487suspending a user's session for later reattachment, 488the logout argument indicates that you 489should terminate the session immediately. 490.It Ic mode Ar type 491.Ar Type 492is one of several options, depending on the state of the 493.Tn TELNET 494session. 495The remote host is asked for permission to go into the requested mode. 496If the remote host is capable of entering that mode, the requested 497mode will be entered. 498.Bl -tag -width Ar 499.It Ic character 500Disable the 501.Dv TELNET LINEMODE 502option, or, if the remote side does not understand the 503.Dv LINEMODE 504option, then enter \*(Lqcharacter at a time\*(Lq mode. 505.It Ic line 506Enable the 507.Dv TELNET LINEMODE 508option, or, if the remote side does not understand the 509.Dv LINEMODE 510option, then attempt to enter \*(Lqold-line-by-line\*(Lq mode. 511.It Ic isig Pq Ic \-isig 512Attempt to enable (disable) the 513.Dv TRAPSIG 514mode of the 515.Dv LINEMODE 516option. 517This requires that the 518.Dv LINEMODE 519option be enabled. 520.It Ic edit Pq Ic \-edit 521Attempt to enable (disable) the 522.Dv EDIT 523mode of the 524.Dv LINEMODE 525option. 526This requires that the 527.Dv LINEMODE 528option be enabled. 529.It Ic softtabs Pq Ic \-softtabs 530Attempt to enable (disable) the 531.Dv SOFT_TAB 532mode of the 533.Dv LINEMODE 534option. 535This requires that the 536.Dv LINEMODE 537option be enabled. 538.It Ic litecho Pq Ic \-litecho 539Attempt to enable (disable) the 540.Dv LIT_ECHO 541mode of the 542.Dv LINEMODE 543option. 544This requires that the 545.Dv LINEMODE 546option be enabled. 547.It Ic \&? 548Prints out help information for the 549.Ic mode 550command. 551.El 552.It Ic open Ar host Oo Fl l Ar user Oc Oo Fl a Oc Oo Oo \&- Oc Ns Ar port Oc 553Open a connection to the named host. 554If no port number 555is specified, 556.Nm 557will attempt to contact a 558.Tn TELNET 559server at the default port. 560The host specification may be either a host name (see 561.Xr hosts 5 ) 562or an Internet address specified in the \*(Lqdot notation\*(Rq (see 563.Xr inet 3 ) . 564The 565.Fl l 566option may be used to specify the user name 567to be passed to the remote system via the 568.Ev ENVIRON 569option. 570If a port is specified 571.Nm 572omits any automatic initialisation of 573.Tn TELNET 574options. 575When the port number is preceded by a minus sign, 576the initial option negotiation is done. 577.Pp 578After establishing a connection, the file 579.Pa \&.telnetrc 580in the 581user's home directory is read. 582Lines beginning with a # are 583comment lines. 584Blank lines are ignored. 585Lines that begin 586without white space are the start of a machine entry. 587The first thing on such a line is a string identifying the machine 588that is being connected to. 589It may be the hostname or numeric address specified as the argument 590.Ar host , 591the canonical name of that string as determined by 592.Xr getaddrinfo 3 , 593or the string 594.Dq DEFAULT 595indicating all hosts. 596The rest of the line, and successive 597lines that begin with white space are assumed to be 598.Nm 599commands and are processed as if they had been typed 600in manually to the 601.Nm 602command prompt. 603.It Ic quit 604Close any open 605.Tn TELNET 606session and exit 607.Nm . 608An end of file (in command mode) will also close a session and exit. 609.It Ic send Ar arguments 610Sends one or more special character sequences to the remote host. 611The following are the arguments which may be specified 612(more than one argument may be specified at a time): 613.Bl -tag -width escape 614.It Ic abort 615Sends the 616.Dv TELNET ABORT 617(Abort 618processes) 619sequence. 620.It Ic ao 621Sends the 622.Dv TELNET AO 623(Abort Output) sequence, which should cause the remote system to flush 624all output 625.Em from 626the remote system 627.Em to 628the user's terminal. 629.It Ic ayt 630Sends the 631.Dv TELNET AYT 632(Are You There) 633sequence, to which the remote system may or may not choose to respond. 634.It Ic brk 635Sends the 636.Dv TELNET BRK 637(Break) sequence, which may have significance to the remote 638system. 639.It Ic ec 640Sends the 641.Dv TELNET EC 642(Erase Character) 643sequence, which should cause the remote system to erase the last character 644entered. 645.It Ic el 646Sends the 647.Dv TELNET EL 648(Erase Line) 649sequence, which should cause the remote system to erase the line currently 650being entered. 651.It Ic eof 652Sends the 653.Dv TELNET EOF 654(End Of File) 655sequence. 656.It Ic eor 657Sends the 658.Dv TELNET EOR 659(End of Record) 660sequence. 661.It Ic escape 662Sends the current 663.Nm 664escape character (initially \*(Lq^\*(Rq). 665.It Ic ga 666Sends the 667.Dv TELNET GA 668(Go Ahead) 669sequence, which likely has no significance to the remote system. 670.It Ic getstatus 671If the remote side supports the 672.Dv TELNET STATUS 673command, 674.Ic getstatus 675will send the subnegotiation to request that the server send 676its current option status. 677.It Ic ip 678Sends the 679.Dv TELNET IP 680(Interrupt Process) sequence, which should cause the remote 681system to abort the currently running process. 682.It Ic nop 683Sends the 684.Dv TELNET NOP 685(No OPeration) 686sequence. 687.It Ic susp 688Sends the 689.Dv TELNET SUSP 690(SUSPend process) 691sequence. 692.It Ic synch 693Sends the 694.Dv TELNET SYNCH 695sequence. 696This sequence causes the remote system to discard all previously typed 697(but not yet read) input. 698This sequence is sent as 699.Tn TCP 700urgent 701data (and may not work if the remote system is a 702.Bx 4.2 703system \(em if 704it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal). 705.It Ic do Ar cmd 706.It Ic dont Ar cmd 707.It Ic will Ar cmd 708.It Ic wont Ar cmd 709Sends the 710.Dv TELNET DO 711.Ar cmd 712sequence. 713.Ar Cmd 714can be either a decimal number between 0 and 255, 715or a symbolic name for a specific 716.Dv TELNET 717command. 718.Ar Cmd 719can also be either 720.Ic help 721or 722.Ic \&? 723to print out help information, including 724a list of known symbolic names. 725.It Ic \&? 726Prints out help information for the 727.Ic send 728command. 729.El 730.It Ic set Ar argument value 731.It Ic unset Ar argument value 732The 733.Ic set 734command will set any one of a number of 735.Nm 736variables to a specific value or to 737.Dv TRUE . 738The special value 739.Ic off 740turns off the function associated with 741the variable, this is equivalent to using the 742.Ic unset 743command. 744The 745.Ic unset 746command will disable or set to 747.Dv FALSE 748any of the specified functions. 749The values of variables may be interrogated with the 750.Ic display 751command. 752The variables which may be set or unset, but not toggled, are 753listed here. 754In addition, any of the variables for the 755.Ic toggle 756command may be explicitly set or unset using 757the 758.Ic set 759and 760.Ic unset 761commands. 762.Bl -tag -width escape 763.It Ic ayt 764If 765.Tn TELNET 766is in localchars mode, or 767.Dv LINEMODE 768is enabled, and the status character is typed, a 769.Dv TELNET AYT 770sequence (see 771.Ic send ayt 772above) is sent to the 773remote host. 774The initial value for the "Are You There" 775character is the terminal's status character. 776.It Ic echo 777This is the value (initially \*(Lq^E\*(Rq) which, when in 778\*(Lqline by line\*(Rq mode, toggles between doing local echoing 779of entered characters (for normal processing), and suppressing 780echoing of entered characters (for entering, say, a password). 781.It Ic eof 782If 783.Nm 784is operating in 785.Dv LINEMODE 786or \*(Lqold line by line\*(Rq mode, entering this character 787as the first character on a line will cause this character to be 788sent to the remote system. 789The initial value of the eof character is taken to be the terminal's 790.Ic eof 791character. 792.It Ic erase 793If 794.Nm 795is in 796.Ic localchars 797mode (see 798.Ic toggle 799.Ic localchars 800below), 801.Sy and 802if 803.Nm 804is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 805character is typed, a 806.Dv TELNET EC 807sequence (see 808.Ic send 809.Ic ec 810above) 811is sent to the remote system. 812The initial value for the erase character is taken to be 813the terminal's 814.Ic erase 815character. 816.It Ic escape 817This is the 818.Nm 819escape character (initially \*(Lq^[\*(Rq) which causes entry 820into 821.Nm 822command mode (when connected to a remote system). 823.It Ic flushoutput 824If 825.Nm 826is in 827.Ic localchars 828mode (see 829.Ic toggle 830.Ic localchars 831below) 832and the 833.Ic flushoutput 834character is typed, a 835.Dv TELNET AO 836sequence (see 837.Ic send 838.Ic ao 839above) 840is sent to the remote host. 841The initial value for the flush character is taken to be 842the terminal's 843.Ic flush 844character. 845.It Ic forw1 846.It Ic forw2 847If 848.Tn TELNET 849is operating in 850.Dv LINEMODE , 851these are the 852characters that, when typed, cause partial lines to be 853forwarded to the remote system. 854The initial value for 855the forwarding characters are taken from the terminal's 856eol and eol2 characters. 857.It Ic interrupt 858If 859.Nm 860is in 861.Ic localchars 862mode (see 863.Ic toggle 864.Ic localchars 865below) 866and the 867.Ic interrupt 868character is typed, a 869.Dv TELNET IP 870sequence (see 871.Ic send 872.Ic ip 873above) 874is sent to the remote host. 875The initial value for the interrupt character is taken to be 876the terminal's 877.Ic intr 878character. 879.It Ic kill 880If 881.Nm 882is in 883.Ic localchars 884mode (see 885.Ic toggle 886.Ic localchars 887below), 888.Ic and 889if 890.Nm 891is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 892character is typed, a 893.Dv TELNET EL 894sequence (see 895.Ic send 896.Ic el 897above) 898is sent to the remote system. 899The initial value for the kill character is taken to be 900the terminal's 901.Ic kill 902character. 903.It Ic lnext 904If 905.Nm 906is operating in 907.Dv LINEMODE 908or \*(Lqold line by line\*(Lq mode, then this character is taken to 909be the terminal's 910.Ic lnext 911character. 912The initial value for the lnext character is taken to be 913the terminal's 914.Ic lnext 915character. 916.It Ic quit 917If 918.Nm 919is in 920.Ic localchars 921mode (see 922.Ic toggle 923.Ic localchars 924below) 925and the 926.Ic quit 927character is typed, a 928.Dv TELNET BRK 929sequence (see 930.Ic send 931.Ic brk 932above) 933is sent to the remote host. 934The initial value for the quit character is taken to be 935the terminal's 936.Ic quit 937character. 938.It Ic reprint 939If 940.Nm 941is operating in 942.Dv LINEMODE 943or \*(Lqold line by line\*(Lq mode, then this character is taken to 944be the terminal's 945.Ic reprint 946character. 947The initial value for the reprint character is taken to be 948the terminal's 949.Ic reprint 950character. 951.It Ic rlogin 952This is the rlogin escape character. 953If set, the normal 954.Tn TELNET 955escape character is ignored unless it is 956preceded by this character at the beginning of a line. 957This character, at the beginning of a line followed by 958a "." closes the connection; when followed by a ^Z it 959suspends the 960.Nm 961command. 962The initial state is to 963disable the rlogin escape character. 964.It Ic start 965If the 966.Dv TELNET TOGGLE-FLOW-CONTROL 967option has been enabled, 968then this character is taken to 969be the terminal's 970.Ic start 971character. 972The initial value for the start character is taken to be 973the terminal's 974.Ic start 975character. 976.It Ic stop 977If the 978.Dv TELNET TOGGLE-FLOW-CONTROL 979option has been enabled, 980then this character is taken to 981be the terminal's 982.Ic stop 983character. 984The initial value for the stop character is taken to be 985the terminal's 986.Ic stop 987character. 988.It Ic susp 989If 990.Nm 991is in 992.Ic localchars 993mode, or 994.Dv LINEMODE 995is enabled, and the 996.Ic suspend 997character is typed, a 998.Dv TELNET SUSP 999sequence (see 1000.Ic send 1001.Ic susp 1002above) 1003is sent to the remote host. 1004The initial value for the suspend character is taken to be 1005the terminal's 1006.Ic suspend 1007character. 1008.It Ic tracefile 1009This is the file to which the output, caused by 1010.Ic netdata 1011or 1012.Ic option 1013tracing being 1014.Dv TRUE , 1015will be written. 1016If it is set to 1017.Dq Fl , 1018then tracing information will be written to standard output (the default). 1019.It Ic worderase 1020If 1021.Nm 1022is operating in 1023.Dv LINEMODE 1024or \*(Lqold line by line\*(Lq mode, then this character is taken to 1025be the terminal's 1026.Ic worderase 1027character. 1028The initial value for the worderase character is taken to be 1029the terminal's 1030.Ic worderase 1031character. 1032.It Ic \&? 1033Displays the legal 1034.Ic set 1035.Pq Ic unset 1036commands. 1037.El 1038.It Ic slc Ar state 1039The 1040.Ic slc 1041command (Set Local Characters) is used to set 1042or change the state of the special 1043characters when the 1044.Dv TELNET LINEMODE 1045option has 1046been enabled. 1047Special characters are characters that get 1048mapped to 1049.Tn TELNET 1050commands sequences (like 1051.Ic ip 1052or 1053.Ic quit ) 1054or line editing characters (like 1055.Ic erase 1056and 1057.Ic kill ) . 1058By default, the local special characters are exported. 1059.Bl -tag -width Fl 1060.It Ic check 1061Verify the current settings for the current special characters. 1062The remote side is requested to send all the current special 1063character settings, and if there are any discrepancies with 1064the local side, the local side will switch to the remote value. 1065.It Ic export 1066Switch to the local defaults for the special characters. 1067The 1068local default characters are those of the local terminal at 1069the time when 1070.Nm 1071was started. 1072.It Ic import 1073Switch to the remote defaults for the special characters. 1074The remote default characters are those of the remote system 1075at the time when the 1076.Tn TELNET 1077connection was established. 1078.It Ic \&? 1079Prints out help information for the 1080.Ic slc 1081command. 1082.El 1083.It Ic status 1084Show the current status of 1085.Nm . 1086This includes the peer one is connected to, as well 1087as the current mode. 1088.It Ic toggle Ar arguments ... 1089Toggle (between 1090.Dv TRUE 1091and 1092.Dv FALSE ) 1093various flags that control how 1094.Nm 1095responds to events. 1096These flags may be set explicitly to 1097.Dv TRUE 1098or 1099.Dv FALSE 1100using the 1101.Ic set 1102and 1103.Ic unset 1104commands listed above. 1105More than one argument may be specified. 1106The state of these flags may be interrogated with the 1107.Ic display 1108command. 1109Valid arguments are: 1110.Bl -tag -width Ar 1111.It Ic authdebug 1112Turns on debugging information for the authentication code. 1113.It Ic autoflush 1114If 1115.Ic autoflush 1116and 1117.Ic localchars 1118are both 1119.Dv TRUE , 1120then when the 1121.Ic ao , 1122or 1123.Ic quit 1124characters are recognized (and transformed into 1125.Tn TELNET 1126sequences; see 1127.Ic set 1128above for details), 1129.Nm 1130refuses to display any data on the user's terminal 1131until the remote system acknowledges (via a 1132.Dv TELNET TIMING MARK 1133option) 1134that it has processed those 1135.Tn TELNET 1136sequences. 1137The initial value for this toggle is 1138.Dv TRUE 1139if the terminal user had not 1140done an "stty noflsh", otherwise 1141.Dv FALSE 1142(see 1143.Xr stty 1 ) . 1144.It Ic autodecrypt 1145When the 1146.Dv TELNET ENCRYPT 1147option is negotiated, by 1148default the actual encryption (decryption) of the data 1149stream does not start automatically. 1150The autoencrypt 1151(autodecrypt) command states that encryption of the 1152output (input) stream should be enabled as soon as 1153possible. 1154.Pp 1155Note: Because of export controls, the 1156.Dv TELNET ENCRYPT 1157option is not supported outside the United States and Canada. 1158.It Ic autologin 1159If the remote side supports the 1160.Dv TELNET AUTHENTICATION 1161option 1162.Tn TELNET 1163attempts to use it to perform automatic authentication. 1164If the 1165.Dv AUTHENTICATION 1166option is not supported, the user's login 1167name are propagated through the 1168.Dv TELNET ENVIRON 1169option. 1170This command is the same as specifying the 1171.Fl a 1172option on the 1173.Ic open 1174command. 1175.It Ic autosynch 1176If 1177.Ic autosynch 1178and 1179.Ic localchars 1180are both 1181.Dv TRUE , 1182then when either the 1183.Ic intr 1184or 1185.Ic quit 1186characters is typed (see 1187.Ic set 1188above for descriptions of the 1189.Ic intr 1190and 1191.Ic quit 1192characters), the resulting 1193.Tn TELNET 1194sequence sent is followed by the 1195.Dv TELNET SYNCH 1196sequence. 1197This procedure 1198.Ic should 1199cause the remote system to begin throwing away all previously 1200typed input until both of the 1201.Tn TELNET 1202sequences have been read and acted upon. 1203The initial value of this toggle is 1204.Dv FALSE . 1205.It Ic binary 1206Enable or disable the 1207.Dv TELNET BINARY 1208option on both input and output. 1209.It Ic inbinary 1210Enable or disable the 1211.Dv TELNET BINARY 1212option on input. 1213.It Ic outbinary 1214Enable or disable the 1215.Dv TELNET BINARY 1216option on output. 1217.It Ic crlf 1218If this is 1219.Dv TRUE , 1220then carriage returns will be sent as 1221.Li <CR><LF> . 1222If this is 1223.Dv FALSE , 1224then carriage returns will be send as 1225.Li <CR><NUL> . 1226The initial value for this toggle is 1227.Dv FALSE . 1228.It Ic crmod 1229Toggle carriage return mode. 1230When this mode is enabled, most carriage return characters received from 1231the remote host will be mapped into a carriage return followed by 1232a line feed. 1233This mode does not affect those characters typed by the user, only 1234those received from the remote host. 1235This mode is not very useful unless the remote host 1236only sends carriage return, but never line feed. 1237The initial value for this toggle is 1238.Dv FALSE . 1239.It Ic debug 1240Toggles socket level debugging (useful only to the 1241.Ic super user ) . 1242The initial value for this toggle is 1243.Dv FALSE . 1244.It Ic encdebug 1245Turns on debugging information for the encryption code. 1246.It Ic localchars 1247If this is 1248.Dv TRUE , 1249then the 1250.Ic flush , 1251.Ic interrupt , 1252.Ic quit , 1253.Ic erase , 1254and 1255.Ic kill 1256characters (see 1257.Ic set 1258above) are recognized locally, and transformed into (hopefully) appropriate 1259.Tn TELNET 1260control sequences 1261(respectively 1262.Ic ao , 1263.Ic ip , 1264.Ic brk , 1265.Ic ec , 1266and 1267.Ic el ; 1268see 1269.Ic send 1270above). 1271The initial value for this toggle is 1272.Dv TRUE 1273in \*(Lqold line by line\*(Rq mode, 1274and 1275.Dv FALSE 1276in \*(Lqcharacter at a time\*(Rq mode. 1277When the 1278.Dv LINEMODE 1279option is enabled, the value of 1280.Ic localchars 1281is ignored, and assumed to always be 1282.Dv TRUE . 1283If 1284.Dv LINEMODE 1285has ever been enabled, then 1286.Ic quit 1287is sent as 1288.Ic abort , 1289and 1290.Ic eof and 1291.Ic suspend 1292are sent as 1293.Ic eof and 1294.Ic susp 1295(see 1296.Ic send 1297above). 1298.It Ic netdata 1299Toggles the display of all network data (in hexadecimal format). 1300The initial value for this toggle is 1301.Dv FALSE . 1302.It Ic options 1303Toggles the display of some internal 1304.Nm 1305protocol processing (having to do with 1306.Tn TELNET 1307options). 1308The initial value for this toggle is 1309.Dv FALSE . 1310.It Ic prettydump 1311When the 1312.Ic netdata 1313toggle is enabled, if 1314.Ic prettydump 1315is enabled the output from the 1316.Ic netdata 1317command will be formatted in a more user readable format. 1318Spaces are put between each character in the output, and the 1319beginning of any 1320.Tn TELNET 1321escape sequence is preceded by a '*' to aid in locating them. 1322.It Ic skiprc 1323When the skiprc toggle is 1324.Dv TRUE , 1325.Tn TELNET 1326skips the reading of the 1327.Pa \&.telnetrc 1328file in the users home 1329directory when connections are opened. 1330The initial 1331value for this toggle is 1332.Dv FALSE . 1333.It Ic termdata 1334Toggles the display of all terminal data (in hexadecimal format). 1335The initial value for this toggle is 1336.Dv FALSE . 1337.It Ic verbose_encrypt 1338When the 1339.Ic verbose_encrypt 1340toggle is 1341.Dv TRUE , 1342.Nm 1343prints out a message each time encryption is enabled or 1344disabled. 1345The initial value for this toggle is 1346.Dv FALSE . 1347Note: Because of export controls, data encryption 1348is not supported outside of the United States and Canada. 1349.It Ic \&? 1350Displays the legal 1351.Ic toggle 1352commands. 1353.El 1354.It Ic z 1355Suspend 1356.Nm . 1357This command only works when the user is using the 1358.Xr csh 1 . 1359.It Ic \&! Op Ar command 1360Execute a single command in a subshell on the local 1361system. 1362If 1363.Ar command 1364is omitted, then an interactive 1365subshell is invoked. 1366.It Ic \&? Op Ar command 1367Get help. 1368With no arguments, 1369.Nm 1370prints a help summary. 1371If a command is specified, 1372.Nm 1373will print the help information for just that command. 1374.El 1375.Sh ENVIRONMENT 1376.Nm 1377uses at least the 1378.Ev HOME , 1379.Ev SHELL , 1380.Ev DISPLAY , 1381and 1382.Ev TERM 1383environment variables. 1384Other environment variables may be propagated 1385to the other side via the 1386.Dv TELNET ENVIRON 1387option. 1388.Sh FILES 1389.Bl -tag -width ~/.telnetrc -compact 1390.It Pa ~/.telnetrc 1391user customized telnet startup values 1392.El 1393.Sh HISTORY 1394The 1395.Nm 1396command appeared in 1397.Bx 4.2 . 1398IPsec support was added by WIDE/KAME project, in 1999. 1399.Sh NOTES 1400On some remote systems, echo has to be turned off manually when in 1401\*(Lqold line by line\*(Rq mode. 1402.Pp 1403In \*(Lqold line by line\*(Rq mode or 1404.Dv LINEMODE 1405the terminal's 1406.Ic eof 1407character is only recognized (and sent to the remote system) 1408when it is the first character on a line. 1409