1.\" Copyright (c) 1983, 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.roff% 5.\" 6.\" @(#)telnet.1 8.5 (Berkeley) 03/01/94 7.\" 8.Dd 9.Dt TELNET 1 10.Os BSD 4.2 11.Sh NAME 12.Nm telnet 13.Nd user interface to the 14.Tn TELNET 15protocol 16.Sh SYNOPSIS 17.Nm telnet 18.Op Fl 8EFKLacdfrx 19.Op Fl S Ar tos 20.Op Fl X Ar authtype 21.Op Fl e Ar escapechar 22.Op Fl k Ar realm 23.Op Fl l Ar user 24.Op Fl n Ar tracefile 25.Oo 26.Ar host 27.Op port 28.Oc 29.Sh DESCRIPTION 30The 31.Nm telnet 32command 33is used to communicate with another host using the 34.Tn TELNET 35protocol. 36If 37.Nm telnet 38is invoked without the 39.Ar host 40argument, it enters command mode, 41indicated by its prompt 42.Pq Nm telnet\&> . 43In this mode, it accepts and executes the commands listed below. 44If it is invoked with arguments, it performs an 45.Ic open 46command with those arguments. 47.Pp 48Options: 49.Bl -tag -width indent 50.It Fl 8 51Specifies an 8-bit data path. This causes an attempt to 52negotiate the 53.Dv TELNET BINARY 54option on both input and output. 55.It Fl E 56Stops any character from being recognized as an escape character. 57.It Fl F 58If Kerberos V5 authentication is being used, the 59.Fl F 60option allows the local credentials to be forwarded 61to the remote system, including any credentials that 62have already been forwarded into the local environment. 63.It Fl K 64Specifies no automatic login to the remote system. 65.It Fl L 66Specifies an 8-bit data path on output. This causes the 67BINARY option to be negotiated on output. 68.It Fl S Ar tos 69Sets the IP type-of-service (TOS) option for the telnet 70connection to the value 71.Ar tos, 72which can be a numeric TOS value 73or, on systems that support it, a symbolic 74TOS name found in the /etc/iptos file. 75.It Fl X Ar atype 76Disables the 77.Ar atype 78type of authentication. 79.It Fl a 80Attempt automatic login. 81Currently, this sends the user name via the 82.Ev USER 83variable 84of the 85.Ev ENVIRON 86option if supported by the remote system. 87The name used is that of the current user as returned by 88.Xr getlogin 2 89if it agrees with the current user ID, 90otherwise it is the name associated with the user ID. 91.It Fl c 92Disables the reading of the user's 93.Pa \&.telnetrc 94file. (See the 95.Ic toggle skiprc 96command on this man page.) 97.It Fl d 98Sets the initial value of the 99.Ic debug 100toggle to 101.Dv TRUE 102.It Fl e Ar escape char 103Sets the initial 104.Nm 105.Nm telnet 106escape character to 107.Ar escape char. 108If 109.Ar escape char 110is omitted, then 111there will be no escape character. 112.It Fl f 113If Kerberos V5 authentication is being used, the 114.Fl f 115option allows the local credentials to be forwarded to the remote system. 116.It Fl k Ar realm 117If Kerberos authentication is being used, the 118.Fl k 119option requests that telnet obtain tickets for the remote host in 120realm realm instead of the remote host's realm, as determined 121by 122.Xr krb_realmofhost 3 . 123.It Fl l Ar user 124When connecting to the remote system, if the remote system 125understands the 126.Ev ENVIRON 127option, then 128.Ar user 129will be sent to the remote system as the value for the variable USER. 130This option implies the 131.Fl a 132option. 133This option may also be used with the 134.Ic open 135command. 136.It Fl n Ar tracefile 137Opens 138.Ar tracefile 139for recording trace information. 140See the 141.Ic set tracefile 142command below. 143.It Fl r 144Specifies a user interface similar to 145.Xr rlogin 1 . 146In this 147mode, the escape character is set to the tilde (~) character, 148unless modified by the -e option. 149.It Fl x 150Turns on encryption of the data stream if possible. This 151option is not available outside of the United States and 152Canada. 153.It Ar host 154Indicates the official name, an alias, or the Internet address 155of a remote host. 156.It Ar port 157Indicates a port number (address of an application). If a number is 158not specified, the default 159.Nm telnet 160port is used. 161.El 162.Pp 163When in rlogin mode, a line of the form ~. disconnects from the 164remote host; ~ is the telnet escape character. 165Similarly, the line ~^Z suspends the telnet session. 166The line ~^] escapes to the normal telnet escape prompt. 167.Pp 168Once a connection has been opened, 169.Nm telnet 170will attempt to enable the 171.Dv TELNET LINEMODE 172option. 173If this fails, then 174.Nm telnet 175will revert to one of two input modes: 176either \*(Lqcharacter at a time\*(Rq 177or \*(Lqold line by line\*(Rq 178depending on what the remote system supports. 179.Pp 180When 181.Dv LINEMODE 182is enabled, character processing is done on the 183local system, under the control of the remote system. When input 184editing or character echoing is to be disabled, the remote system 185will relay that information. The remote system will also relay 186changes to any special characters that happen on the remote 187system, so that they can take effect on the local system. 188.Pp 189In \*(Lqcharacter at a time\*(Rq mode, most 190text typed is immediately sent to the remote host for processing. 191.Pp 192In \*(Lqold line by line\*(Rq mode, all text is echoed locally, 193and (normally) only completed lines are sent to the remote host. 194The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used 195to turn off and on the local echo 196(this would mostly be used to enter passwords 197without the password being echoed). 198.Pp 199If the 200.Dv LINEMODE 201option is enabled, or if the 202.Ic localchars 203toggle is 204.Dv TRUE 205(the default for \*(Lqold line by line\*(Lq; see below), 206the user's 207.Ic quit , 208.Ic intr , 209and 210.Ic flush 211characters are trapped locally, and sent as 212.Tn TELNET 213protocol sequences to the remote side. 214If 215.Dv LINEMODE 216has ever been enabled, then the user's 217.Ic susp 218and 219.Ic eof 220are also sent as 221.Tn TELNET 222protocol sequences, 223and 224.Ic quit 225is sent as a 226.Dv TELNET ABORT 227instead of 228.Dv BREAK 229There are options (see 230.Ic toggle 231.Ic autoflush 232and 233.Ic toggle 234.Ic autosynch 235below) 236which cause this action to flush subsequent output to the terminal 237(until the remote host acknowledges the 238.Tn TELNET 239sequence) and flush previous terminal input 240(in the case of 241.Ic quit 242and 243.Ic intr ) . 244.Pp 245While connected to a remote host, 246.Nm telnet 247command mode may be entered by typing the 248.Nm telnet 249\*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq). 250When in command mode, the normal terminal editing conventions are available. 251.Pp 252The following 253.Nm telnet 254commands are available. 255Only enough of each command to uniquely identify it need be typed 256(this is also true for arguments to the 257.Ic mode , 258.Ic set , 259.Ic toggle , 260.Ic unset , 261.Ic slc , 262.Ic environ , 263and 264.Ic display 265commands). 266.Pp 267.Bl -tag -width "mode type" 268.It Ic auth Ar argument ... 269The auth command manipulates the information sent through the 270.Dv TELNET AUTHENTICATE 271option. Valid arguments for the 272auth command are as follows: 273.Bl -tag -width "disable type" 274.It Ic disable Ar type 275Disables the specified type of authentication. To 276obtain a list of available types, use the 277.Ic auth disable \&? 278command. 279.It Ic enable Ar type 280Enables the specified type of authentication. To 281obtain a list of available types, use the 282.Ic auth enable \&? 283command. 284.It Ic status 285Lists the current status of the various types of 286authentication. 287.El 288.It Ic close 289Close a 290.Tn TELNET 291session and return to command mode. 292.It Ic display Ar argument ... 293Displays all, or some, of the 294.Ic set 295and 296.Ic toggle 297values (see below). 298.It Ic encrypt Ar argument ... 299The encrypt command manipulates the information sent through the 300.Dv TELNET ENCRYPT 301option. 302.Pp 303Note: Because of export controls, the 304.Dv TELNET ENCRYPT 305option is not supported outside of the United States and Canada. 306.Pp 307Valid arguments for the encrypt command are as follows: 308.Bl -tag -width Ar 309.It Ic disable Ar type Ic [input|output] 310Disables the specified type of encryption. If you 311omit the input and output, both input and output 312are disabled. To obtain a list of available 313types, use the 314.Ic encrypt disable \&? 315command. 316.It Ic enable Ar type Ic [input|output] 317Enables the specified type of encryption. If you 318omit input and output, both input and output are 319enabled. To obtain a list of available types, use the 320.Ic encrypt enable \&? 321command. 322.It Ic input 323This is the same as the 324.Ic encrypt start input 325command. 326.It Ic -input 327This is the same as the 328.Ic encrypt stop input 329command. 330.It Ic output 331This is the same as the 332.Ic encrypt start output 333command. 334.It Ic -output 335This is the same as the 336.Ic encrypt stop output 337command. 338.It Ic start Ic [input|output] 339Attempts to start encryption. If you omit 340.Ic input 341and 342.Ic output, 343both input and output are enabled. To 344obtain a list of available types, use the 345.Ic encrypt enable \&? 346command. 347.It Ic status 348Lists the current status of encryption. 349.It Ic stop Ic [input|output] 350Stops encryption. If you omit input and output, 351encryption is on both input and output. 352.It Ic type Ar type 353Sets the default type of encryption to be used 354with later 355.Ic encrypt start 356or 357.Ic encrypt stop 358commands. 359.El 360.It Ic environ Ar arguments... 361The 362.Ic environ 363command is used to manipulate the 364the variables that my be sent through the 365.Dv TELNET ENVIRON 366option. 367The initial set of variables is taken from the users 368environment, with only the 369.Ev DISPLAY 370and 371.Ev PRINTER 372variables being exported by default. 373The 374.Ev USER 375variable is also exported if the 376.Fl a 377or 378.Fl l 379options are used. 380.br 381Valid arguments for the 382.Ic environ 383command are: 384.Bl -tag -width Fl 385.It Ic define Ar variable value 386Define the variable 387.Ar variable 388to have a value of 389.Ar value. 390Any variables defined by this command are automatically exported. 391The 392.Ar value 393may be enclosed in single or double quotes so 394that tabs and spaces may be included. 395.It Ic undefine Ar variable 396Remove 397.Ar variable 398from the list of environment variables. 399.It Ic export Ar variable 400Mark the variable 401.Ar variable 402to be exported to the remote side. 403.It Ic unexport Ar variable 404Mark the variable 405.Ar variable 406to not be exported unless 407explicitly asked for by the remote side. 408.It Ic list 409List the current set of environment variables. 410Those marked with a 411.Cm * 412will be sent automatically, 413other variables will only be sent if explicitly requested. 414.It Ic \&? 415Prints out help information for the 416.Ic environ 417command. 418.El 419.It Ic logout 420Sends the 421.Dv TELNET LOGOUT 422option to the remote side. 423This command is similar to a 424.Ic close 425command; however, if the remote side does not support the 426.Dv LOGOUT 427option, nothing happens. 428If, however, the remote side does support the 429.Dv LOGOUT 430option, this command should cause the remote side to close the 431.Tn TELNET 432connection. 433If the remote side also supports the concept of 434suspending a user's session for later reattachment, 435the logout argument indicates that you 436should terminate the session immediately. 437.It Ic mode Ar type 438.Ar Type 439is one of several options, depending on the state of the 440.Tn TELNET 441session. 442The remote host is asked for permission to go into the requested mode. 443If the remote host is capable of entering that mode, the requested 444mode will be entered. 445.Bl -tag -width Ar 446.It Ic character 447Disable the 448.Dv TELNET LINEMODE 449option, or, if the remote side does not understand the 450.Dv LINEMODE 451option, then enter \*(Lqcharacter at a time\*(Lq mode. 452.It Ic line 453Enable the 454.Dv TELNET LINEMODE 455option, or, if the remote side does not understand the 456.Dv LINEMODE 457option, then attempt to enter \*(Lqold-line-by-line\*(Lq mode. 458.It Ic isig Pq Ic \-isig 459Attempt to enable (disable) the 460.Dv TRAPSIG 461mode of the 462.Dv LINEMODE 463option. 464This requires that the 465.Dv LINEMODE 466option be enabled. 467.It Ic edit Pq Ic \-edit 468Attempt to enable (disable) the 469.Dv EDIT 470mode of the 471.Dv LINEMODE 472option. 473This requires that the 474.Dv LINEMODE 475option be enabled. 476.It Ic softtabs Pq Ic \-softtabs 477Attempt to enable (disable) the 478.Dv SOFT_TAB 479mode of the 480.Dv LINEMODE 481option. 482This requires that the 483.Dv LINEMODE 484option be enabled. 485.It Ic litecho Pq Ic \-litecho 486Attempt to enable (disable) the 487.Dv LIT_ECHO 488mode of the 489.Dv LINEMODE 490option. 491This requires that the 492.Dv LINEMODE 493option be enabled. 494.It Ic \&? 495Prints out help information for the 496.Ic mode 497command. 498.El 499.It Xo 500.Ic open Ar host 501.Oo Op Fl l 502.Ar user 503.Oc Ns Oo Fl 504.Ar port Oc 505.Xc 506Open a connection to the named host. 507If no port number 508is specified, 509.Nm telnet 510will attempt to contact a 511.Tn TELNET 512server at the default port. 513The host specification may be either a host name (see 514.Xr hosts 5 ) 515or an Internet address specified in the \*(Lqdot notation\*(Rq (see 516.Xr inet 3 ) . 517The 518.Op Fl l 519option may be used to specify the user name 520to be passed to the remote system via the 521.Ev ENVIRON 522option. 523When connecting to a non-standard port, 524.Nm telnet 525omits any automatic initiation of 526.Tn TELNET 527options. When the port number is preceded by a minus sign, 528the initial option negotiation is done. 529After establishing a connection, the file 530.Pa \&.telnetrc 531in the 532users home directory is opened. Lines beginning with a # are 533comment lines. Blank lines are ignored. Lines that begin 534without white space are the start of a machine entry. The 535first thing on the line is the name of the machine that is 536being connected to. The rest of the line, and successive 537lines that begin with white space are assumed to be 538.Nm telnet 539commands and are processed as if they had been typed 540in manually to the 541.Nm telnet 542command prompt. 543.It Ic quit 544Close any open 545.Tn TELNET 546session and exit 547.Nm telnet . 548An end of file (in command mode) will also close a session and exit. 549.It Ic send Ar arguments 550Sends one or more special character sequences to the remote host. 551The following are the arguments which may be specified 552(more than one argument may be specified at a time): 553.Pp 554.Bl -tag -width escape 555.It Ic abort 556Sends the 557.Dv TELNET ABORT 558(Abort 559processes) 560sequence. 561.It Ic ao 562Sends the 563.Dv TELNET AO 564(Abort Output) sequence, which should cause the remote system to flush 565all output 566.Em from 567the remote system 568.Em to 569the user's terminal. 570.It Ic ayt 571Sends the 572.Dv TELNET AYT 573(Are You There) 574sequence, to which the remote system may or may not choose to respond. 575.It Ic brk 576Sends the 577.Dv TELNET BRK 578(Break) sequence, which may have significance to the remote 579system. 580.It Ic ec 581Sends the 582.Dv TELNET EC 583(Erase Character) 584sequence, which should cause the remote system to erase the last character 585entered. 586.It Ic el 587Sends the 588.Dv TELNET EL 589(Erase Line) 590sequence, which should cause the remote system to erase the line currently 591being entered. 592.It Ic eof 593Sends the 594.Dv TELNET EOF 595(End Of File) 596sequence. 597.It Ic eor 598Sends the 599.Dv TELNET EOR 600(End of Record) 601sequence. 602.It Ic escape 603Sends the current 604.Nm telnet 605escape character (initially \*(Lq^\*(Rq). 606.It Ic ga 607Sends the 608.Dv TELNET GA 609(Go Ahead) 610sequence, which likely has no significance to the remote system. 611.It Ic getstatus 612If the remote side supports the 613.Dv TELNET STATUS 614command, 615.Ic getstatus 616will send the subnegotiation to request that the server send 617its current option status. 618.It Ic ip 619Sends the 620.Dv TELNET IP 621(Interrupt Process) sequence, which should cause the remote 622system to abort the currently running process. 623.It Ic nop 624Sends the 625.Dv TELNET NOP 626(No OPeration) 627sequence. 628.It Ic susp 629Sends the 630.Dv TELNET SUSP 631(SUSPend process) 632sequence. 633.It Ic synch 634Sends the 635.Dv TELNET SYNCH 636sequence. 637This sequence causes the remote system to discard all previously typed 638(but not yet read) input. 639This sequence is sent as 640.Tn TCP 641urgent 642data (and may not work if the remote system is a 643.Bx 4.2 644system -- if 645it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal). 646.It Ic do Ar cmd 647.It Ic dont Ar cmd 648.It Ic will Ar cmd 649.It Ic wont Ar cmd 650Sends the 651.Dv TELNET DO 652.Ar cmd 653sequence. 654.Ar Cmd 655can be either a decimal number between 0 and 255, 656or a symbolic name for a specific 657.Dv TELNET 658command. 659.Ar Cmd 660can also be either 661.Ic help 662or 663.Ic \&? 664to print out help information, including 665a list of known symbolic names. 666.It Ic \&? 667Prints out help information for the 668.Ic send 669command. 670.El 671.It Ic set Ar argument value 672.It Ic unset Ar argument value 673The 674.Ic set 675command will set any one of a number of 676.Nm telnet 677variables to a specific value or to 678.Dv TRUE . 679The special value 680.Ic off 681turns off the function associated with 682the variable, this is equivalent to using the 683.Ic unset 684command. 685The 686.Ic unset 687command will disable or set to 688.Dv FALSE 689any of the specified functions. 690The values of variables may be interrogated with the 691.Ic display 692command. 693The variables which may be set or unset, but not toggled, are 694listed here. In addition, any of the variables for the 695.Ic toggle 696command may be explicitly set or unset using 697the 698.Ic set 699and 700.Ic unset 701commands. 702.Bl -tag -width escape 703.It Ic ayt 704If 705.Tn TELNET 706is in localchars mode, or 707.Dv LINEMODE 708is enabled, and the status character is typed, a 709.Dv TELNET AYT 710sequence (see 711.Ic send ayt 712preceding) is sent to the 713remote host. The initial value for the "Are You There" 714character is the terminal's status character. 715.It Ic echo 716This is the value (initially \*(Lq^E\*(Rq) which, when in 717\*(Lqline by line\*(Rq mode, toggles between doing local echoing 718of entered characters (for normal processing), and suppressing 719echoing of entered characters (for entering, say, a password). 720.It Ic eof 721If 722.Nm telnet 723is operating in 724.Dv LINEMODE 725or \*(Lqold line by line\*(Rq mode, entering this character 726as the first character on a line will cause this character to be 727sent to the remote system. 728The initial value of the eof character is taken to be the terminal's 729.Ic eof 730character. 731.It Ic erase 732If 733.Nm telnet 734is in 735.Ic localchars 736mode (see 737.Ic toggle 738.Ic localchars 739below), 740.Sy and 741if 742.Nm telnet 743is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 744character is typed, a 745.Dv TELNET EC 746sequence (see 747.Ic send 748.Ic ec 749above) 750is sent to the remote system. 751The initial value for the erase character is taken to be 752the terminal's 753.Ic erase 754character. 755.It Ic escape 756This is the 757.Nm telnet 758escape character (initially \*(Lq^[\*(Rq) which causes entry 759into 760.Nm telnet 761command mode (when connected to a remote system). 762.It Ic flushoutput 763If 764.Nm telnet 765is in 766.Ic localchars 767mode (see 768.Ic toggle 769.Ic localchars 770below) 771and the 772.Ic flushoutput 773character is typed, a 774.Dv TELNET AO 775sequence (see 776.Ic send 777.Ic ao 778above) 779is sent to the remote host. 780The initial value for the flush character is taken to be 781the terminal's 782.Ic flush 783character. 784.It Ic forw1 785.It Ic forw2 786If 787.Tn TELNET 788is operating in 789.Dv LINEMODE , 790these are the 791characters that, when typed, cause partial lines to be 792forwarded to the remote system. The initial value for 793the forwarding characters are taken from the terminal's 794eol and eol2 characters. 795.It Ic interrupt 796If 797.Nm telnet 798is in 799.Ic localchars 800mode (see 801.Ic toggle 802.Ic localchars 803below) 804and the 805.Ic interrupt 806character is typed, a 807.Dv TELNET IP 808sequence (see 809.Ic send 810.Ic ip 811above) 812is sent to the remote host. 813The initial value for the interrupt character is taken to be 814the terminal's 815.Ic intr 816character. 817.It Ic kill 818If 819.Nm telnet 820is in 821.Ic localchars 822mode (see 823.Ic toggle 824.Ic localchars 825below), 826.Ic and 827if 828.Nm telnet 829is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 830character is typed, a 831.Dv TELNET EL 832sequence (see 833.Ic send 834.Ic el 835above) 836is sent to the remote system. 837The initial value for the kill character is taken to be 838the terminal's 839.Ic kill 840character. 841.It Ic lnext 842If 843.Nm telnet 844is operating in 845.Dv LINEMODE 846or \*(Lqold line by line\*(Lq mode, then this character is taken to 847be the terminal's 848.Ic lnext 849character. 850The initial value for the lnext character is taken to be 851the terminal's 852.Ic lnext 853character. 854.It Ic quit 855If 856.Nm telnet 857is in 858.Ic localchars 859mode (see 860.Ic toggle 861.Ic localchars 862below) 863and the 864.Ic quit 865character is typed, a 866.Dv TELNET BRK 867sequence (see 868.Ic send 869.Ic brk 870above) 871is sent to the remote host. 872The initial value for the quit character is taken to be 873the terminal's 874.Ic quit 875character. 876.It Ic reprint 877If 878.Nm telnet 879is operating in 880.Dv LINEMODE 881or \*(Lqold line by line\*(Lq mode, then this character is taken to 882be the terminal's 883.Ic reprint 884character. 885The initial value for the reprint character is taken to be 886the terminal's 887.Ic reprint 888character. 889.It Ic rlogin 890This is the rlogin escape character. 891If set, the normal 892.Tn TELNET 893escape character is ignored unless it is 894preceded by this character at the beginning of a line. 895This character, at the beginning of a line followed by 896a "." closes the connection; when followed by a ^Z it 897suspends the telnet command. The initial state is to 898disable the rlogin escape character. 899.It Ic start 900If the 901.Dv TELNET TOGGLE-FLOW-CONTROL 902option has been enabled, 903then this character is taken to 904be the terminal's 905.Ic start 906character. 907The initial value for the kill character is taken to be 908the terminal's 909.Ic start 910character. 911.It Ic stop 912If the 913.Dv TELNET TOGGLE-FLOW-CONTROL 914option has been enabled, 915then this character is taken to 916be the terminal's 917.Ic stop 918character. 919The initial value for the kill character is taken to be 920the terminal's 921.Ic stop 922character. 923.It Ic susp 924If 925.Nm telnet 926is in 927.Ic localchars 928mode, or 929.Dv LINEMODE 930is enabled, and the 931.Ic suspend 932character is typed, a 933.Dv TELNET SUSP 934sequence (see 935.Ic send 936.Ic susp 937above) 938is sent to the remote host. 939The initial value for the suspend character is taken to be 940the terminal's 941.Ic suspend 942character. 943.It Ic tracefile 944This is the file to which the output, caused by 945.Ic netdata 946or 947.Ic option 948tracing being 949.Dv TRUE , 950will be written. If it is set to 951.Dq Fl , 952then tracing information will be written to standard output (the default). 953.It Ic worderase 954If 955.Nm telnet 956is operating in 957.Dv LINEMODE 958or \*(Lqold line by line\*(Lq mode, then this character is taken to 959be the terminal's 960.Ic worderase 961character. 962The initial value for the worderase character is taken to be 963the terminal's 964.Ic worderase 965character. 966.It Ic \&? 967Displays the legal 968.Ic set 969.Pq Ic unset 970commands. 971.El 972.It Ic slc Ar state 973The 974.Ic slc 975command (Set Local Characters) is used to set 976or change the state of the the special 977characters when the 978.Dv TELNET LINEMODE 979option has 980been enabled. Special characters are characters that get 981mapped to 982.Tn TELNET 983commands sequences (like 984.Ic ip 985or 986.Ic quit ) 987or line editing characters (like 988.Ic erase 989and 990.Ic kill ) . 991By default, the local special characters are exported. 992.Bl -tag -width Fl 993.It Ic check 994Verify the current settings for the current special characters. 995The remote side is requested to send all the current special 996character settings, and if there are any discrepancies with 997the local side, the local side will switch to the remote value. 998.It Ic export 999Switch to the local defaults for the special characters. The 1000local default characters are those of the local terminal at 1001the time when 1002.Nm telnet 1003was started. 1004.It Ic import 1005Switch to the remote defaults for the special characters. 1006The remote default characters are those of the remote system 1007at the time when the 1008.Tn TELNET 1009connection was established. 1010.It Ic \&? 1011Prints out help information for the 1012.Ic slc 1013command. 1014.El 1015.It Ic status 1016Show the current status of 1017.Nm telnet . 1018This includes the peer one is connected to, as well 1019as the current mode. 1020.It Ic toggle Ar arguments ... 1021Toggle (between 1022.Dv TRUE 1023and 1024.Dv FALSE ) 1025various flags that control how 1026.Nm telnet 1027responds to events. 1028These flags may be set explicitly to 1029.Dv TRUE 1030or 1031.Dv FALSE 1032using the 1033.Ic set 1034and 1035.Ic unset 1036commands listed above. 1037More than one argument may be specified. 1038The state of these flags may be interrogated with the 1039.Ic display 1040command. 1041Valid arguments are: 1042.Bl -tag -width Ar 1043.It Ic authdebug 1044Turns on debugging information for the authentication code. 1045.It Ic autoflush 1046If 1047.Ic autoflush 1048and 1049.Ic localchars 1050are both 1051.Dv TRUE , 1052then when the 1053.Ic ao , 1054or 1055.Ic quit 1056characters are recognized (and transformed into 1057.Tn TELNET 1058sequences; see 1059.Ic set 1060above for details), 1061.Nm telnet 1062refuses to display any data on the user's terminal 1063until the remote system acknowledges (via a 1064.Dv TELNET TIMING MARK 1065option) 1066that it has processed those 1067.Tn TELNET 1068sequences. 1069The initial value for this toggle is 1070.Dv TRUE 1071if the terminal user had not 1072done an "stty noflsh", otherwise 1073.Dv FALSE 1074(see 1075.Xr stty 1 ) . 1076.It Ic autodecrypt 1077When the 1078.Dv TELNET ENCRYPT 1079option is negotiated, by 1080default the actual encryption (decryption) of the data 1081stream does not start automatically. The autoencrypt 1082(autodecrypt) command states that encryption of the 1083output (input) stream should be enabled as soon as 1084possible. 1085.Pp 1086Note: Because of export controls, the 1087.Dv TELNET ENCRYPT 1088option is not supported outside the United States and Canada. 1089.It Ic autologin 1090If the remote side supports the 1091.Dv TELNET AUTHENTICATION 1092option 1093.Tn TELNET 1094attempts to use it to perform automatic authentication. If the 1095.Dv AUTHENTICATION 1096option is not supported, the user's login 1097name are propagated through the 1098.Dv TELNET ENVIRON 1099option. 1100This command is the same as specifying 1101.Ar a 1102option on the 1103.Ic open 1104command. 1105.It Ic autosynch 1106If 1107.Ic autosynch 1108and 1109.Ic localchars 1110are both 1111.Dv TRUE , 1112then when either the 1113.Ic intr 1114or 1115.Ic quit 1116characters is typed (see 1117.Ic set 1118above for descriptions of the 1119.Ic intr 1120and 1121.Ic quit 1122characters), the resulting 1123.Tn TELNET 1124sequence sent is followed by the 1125.Dv TELNET SYNCH 1126sequence. 1127This procedure 1128.Ic should 1129cause the remote system to begin throwing away all previously 1130typed input until both of the 1131.Tn TELNET 1132sequences have been read and acted upon. 1133The initial value of this toggle is 1134.Dv FALSE . 1135.It Ic binary 1136Enable or disable the 1137.Dv TELNET BINARY 1138option on both input and output. 1139.It Ic inbinary 1140Enable or disable the 1141.Dv TELNET BINARY 1142option on input. 1143.It Ic outbinary 1144Enable or disable the 1145.Dv TELNET BINARY 1146option on output. 1147.It Ic crlf 1148If this is 1149.Dv TRUE , 1150then carriage returns will be sent as 1151.Li <CR><LF> . 1152If this is 1153.Dv FALSE , 1154then carriage returns will be send as 1155.Li <CR><NUL> . 1156The initial value for this toggle is 1157.Dv FALSE . 1158.It Ic crmod 1159Toggle carriage return mode. 1160When this mode is enabled, most carriage return characters received from 1161the remote host will be mapped into a carriage return followed by 1162a line feed. 1163This mode does not affect those characters typed by the user, only 1164those received from the remote host. 1165This mode is not very useful unless the remote host 1166only sends carriage return, but never line feed. 1167The initial value for this toggle is 1168.Dv FALSE . 1169.It Ic debug 1170Toggles socket level debugging (useful only to the 1171.Ic super user ) . 1172The initial value for this toggle is 1173.Dv FALSE . 1174.It Ic encdebug 1175Turns on debugging information for the encryption code. 1176.It Ic localchars 1177If this is 1178.Dv TRUE , 1179then the 1180.Ic flush , 1181.Ic interrupt , 1182.Ic quit , 1183.Ic erase , 1184and 1185.Ic kill 1186characters (see 1187.Ic set 1188above) are recognized locally, and transformed into (hopefully) appropriate 1189.Tn TELNET 1190control sequences 1191(respectively 1192.Ic ao , 1193.Ic ip , 1194.Ic brk , 1195.Ic ec , 1196and 1197.Ic el ; 1198see 1199.Ic send 1200above). 1201The initial value for this toggle is 1202.Dv TRUE 1203in \*(Lqold line by line\*(Rq mode, 1204and 1205.Dv FALSE 1206in \*(Lqcharacter at a time\*(Rq mode. 1207When the 1208.Dv LINEMODE 1209option is enabled, the value of 1210.Ic localchars 1211is ignored, and assumed to always be 1212.Dv TRUE . 1213If 1214.Dv LINEMODE 1215has ever been enabled, then 1216.Ic quit 1217is sent as 1218.Ic abort , 1219and 1220.Ic eof and 1221.B suspend 1222are sent as 1223.Ic eof and 1224.Ic susp , 1225see 1226.Ic send 1227above). 1228.It Ic netdata 1229Toggles the display of all network data (in hexadecimal format). 1230The initial value for this toggle is 1231.Dv FALSE . 1232.It Ic options 1233Toggles the display of some internal 1234.Nm telnet 1235protocol processing (having to do with 1236.Tn TELNET 1237options). 1238The initial value for this toggle is 1239.Dv FALSE . 1240.It Ic prettydump 1241When the 1242.Ic netdata 1243toggle is enabled, if 1244.Ic prettydump 1245is enabled the output from the 1246.Ic netdata 1247command will be formatted in a more user readable format. 1248Spaces are put between each character in the output, and the 1249beginning of any 1250.Tn TELNET 1251escape sequence is preceded by a '*' to aid in locating them. 1252.It Ic skiprc 1253When the skiprc toggle is 1254.Dv TRUE , 1255.Tn TELNET 1256skips the reading of the 1257.Pa \&.telnetrc 1258file in the users home 1259directory when connections are opened. The initial 1260value for this toggle is 1261.Dv FALSE. 1262.It Ic termdata 1263Toggles the display of all terminal data (in hexadecimal format). 1264The initial value for this toggle is 1265.Dv FALSE . 1266.It Ic verbose_encrypt 1267When the 1268.Ic verbose_encrypt 1269toggle is 1270.Dv TRUE , 1271.Tn TELNET 1272prints out a message each time encryption is enabled or 1273disabled. The initial value for this toggle is 1274.Dv FALSE. 1275Note: Because of export controls, data encryption 1276is not supported outside of the United States and Canada. 1277.It Ic \&? 1278Displays the legal 1279.Ic toggle 1280commands. 1281.El 1282.It Ic z 1283Suspend 1284.Nm telnet . 1285This command only works when the user is using the 1286.Xr csh 1 . 1287.It Ic \&! Op Ar command 1288Execute a single command in a subshell on the local 1289system. If 1290.Ic command 1291is omitted, then an interactive 1292subshell is invoked. 1293.It Ic \&? Op Ar command 1294Get help. With no arguments, 1295.Nm telnet 1296prints a help summary. 1297If a command is specified, 1298.Nm telnet 1299will print the help information for just that command. 1300.El 1301.Sh ENVIRONMENT 1302.Nm Telnet 1303uses at least the 1304.Ev HOME , 1305.Ev SHELL , 1306.Ev DISPLAY , 1307and 1308.Ev TERM 1309environment variables. 1310Other environment variables may be propagated 1311to the other side via the 1312.Dv TELNET ENVIRON 1313option. 1314.Sh FILES 1315.Bl -tag -width ~/.telnetrc -compact 1316.It Pa ~/.telnetrc 1317user customized telnet startup values 1318.El 1319.Sh HISTORY 1320The 1321.Nm Telnet 1322command appeared in 1323.Bx 4.2 . 1324.Sh NOTES 1325.Pp 1326On some remote systems, echo has to be turned off manually when in 1327\*(Lqold line by line\*(Rq mode. 1328.Pp 1329In \*(Lqold line by line\*(Rq mode or 1330.Dv LINEMODE 1331the terminal's 1332.Ic eof 1333character is only recognized (and sent to the remote system) 1334when it is the first character on a line. 1335