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 8.6 (Berkeley) 06/01/94 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.ne 1i 117.It Fl k Ar realm 118If Kerberos authentication is being used, the 119.Fl k 120option requests that telnet obtain tickets for the remote host in 121realm realm instead of the remote host's realm, as determined 122by 123.Xr krb_realmofhost 3 . 124.It Fl l Ar user 125When connecting to the remote system, if the remote system 126understands the 127.Ev ENVIRON 128option, then 129.Ar user 130will be sent to the remote system as the value for the variable USER. 131This option implies the 132.Fl a 133option. 134This option may also be used with the 135.Ic open 136command. 137.It Fl n Ar tracefile 138Opens 139.Ar tracefile 140for recording trace information. 141See the 142.Ic set tracefile 143command below. 144.It Fl r 145Specifies a user interface similar to 146.Xr rlogin 1 . 147In this 148mode, the escape character is set to the tilde (~) character, 149unless modified by the -e option. 150.It Fl x 151Turns on encryption of the data stream if possible. This 152option is not available outside of the United States and 153Canada. 154.It Ar host 155Indicates the official name, an alias, or the Internet address 156of a remote host. 157.It Ar port 158Indicates a port number (address of an application). If a number is 159not specified, the default 160.Nm telnet 161port is used. 162.El 163.Pp 164When in rlogin mode, a line of the form ~. disconnects from the 165remote host; ~ is the telnet escape character. 166Similarly, the line ~^Z suspends the telnet session. 167The line ~^] escapes to the normal telnet escape prompt. 168.Pp 169Once a connection has been opened, 170.Nm telnet 171will attempt to enable the 172.Dv TELNET LINEMODE 173option. 174If this fails, then 175.Nm telnet 176will revert to one of two input modes: 177either \*(Lqcharacter at a time\*(Rq 178or \*(Lqold line by line\*(Rq 179depending on what the remote system supports. 180.Pp 181When 182.Dv LINEMODE 183is enabled, character processing is done on the 184local system, under the control of the remote system. When input 185editing or character echoing is to be disabled, the remote system 186will relay that information. The remote system will also relay 187changes to any special characters that happen on the remote 188system, so that they can take effect on the local system. 189.Pp 190In \*(Lqcharacter at a time\*(Rq mode, most 191text typed is immediately sent to the remote host for processing. 192.Pp 193In \*(Lqold line by line\*(Rq mode, all text is echoed locally, 194and (normally) only completed lines are sent to the remote host. 195The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used 196to turn off and on the local echo 197(this would mostly be used to enter passwords 198without the password being echoed). 199.Pp 200If the 201.Dv LINEMODE 202option is enabled, or if the 203.Ic localchars 204toggle is 205.Dv TRUE 206(the default for \*(Lqold line by line\*(Lq; see below), 207the user's 208.Ic quit , 209.Ic intr , 210and 211.Ic flush 212characters are trapped locally, and sent as 213.Tn TELNET 214protocol sequences to the remote side. 215If 216.Dv LINEMODE 217has ever been enabled, then the user's 218.Ic susp 219and 220.Ic eof 221are also sent as 222.Tn TELNET 223protocol sequences, 224and 225.Ic quit 226is sent as a 227.Dv TELNET ABORT 228instead of 229.Dv BREAK 230There are options (see 231.Ic toggle 232.Ic autoflush 233and 234.Ic toggle 235.Ic autosynch 236below) 237which cause this action to flush subsequent output to the terminal 238(until the remote host acknowledges the 239.Tn TELNET 240sequence) and flush previous terminal input 241(in the case of 242.Ic quit 243and 244.Ic intr ) . 245.Pp 246While connected to a remote host, 247.Nm telnet 248command mode may be entered by typing the 249.Nm telnet 250\*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq). 251When in command mode, the normal terminal editing conventions are available. 252.Pp 253The following 254.Nm telnet 255commands are available. 256Only enough of each command to uniquely identify it need be typed 257(this is also true for arguments to the 258.Ic mode , 259.Ic set , 260.Ic toggle , 261.Ic unset , 262.Ic slc , 263.Ic environ , 264and 265.Ic display 266commands). 267.Pp 268.Bl -tag -width "mode type" 269.It Ic auth Ar argument ... 270The auth command manipulates the information sent through the 271.Dv TELNET AUTHENTICATE 272option. Valid arguments for the 273auth command are as follows: 274.Bl -tag -width "disable type" 275.It Ic disable Ar type 276Disables the specified type of authentication. To 277obtain a list of available types, use the 278.Ic auth disable \&? 279command. 280.It Ic enable Ar type 281Enables the specified type of authentication. To 282obtain a list of available types, use the 283.Ic auth enable \&? 284command. 285.It Ic status 286Lists the current status of the various types of 287authentication. 288.El 289.It Ic close 290Close a 291.Tn TELNET 292session and return to command mode. 293.It Ic display Ar argument ... 294Displays all, or some, of the 295.Ic set 296and 297.Ic toggle 298values (see below). 299.It Ic encrypt Ar argument ... 300The encrypt command manipulates the information sent through the 301.Dv TELNET ENCRYPT 302option. 303.Pp 304Note: Because of export controls, the 305.Dv TELNET ENCRYPT 306option is not supported outside of the United States and Canada. 307.Pp 308Valid arguments for the encrypt command are as follows: 309.Bl -tag -width Ar 310.It Ic disable Ar type Ic [input|output] 311Disables the specified type of encryption. If you 312omit the input and output, both input and output 313are disabled. To obtain a list of available 314types, use the 315.Ic encrypt disable \&? 316command. 317.It Ic enable Ar type Ic [input|output] 318Enables the specified type of encryption. If you 319omit input and output, both input and output are 320enabled. To obtain a list of available types, use the 321.Ic encrypt enable \&? 322command. 323.It Ic input 324This is the same as the 325.Ic encrypt start input 326command. 327.It Ic -input 328This is the same as the 329.Ic encrypt stop input 330command. 331.It Ic output 332This is the same as the 333.Ic encrypt start output 334command. 335.It Ic -output 336This is the same as the 337.Ic encrypt stop output 338command. 339.It Ic start Ic [input|output] 340Attempts to start encryption. If you omit 341.Ic input 342and 343.Ic output, 344both input and output are enabled. To 345obtain a list of available types, use the 346.Ic encrypt enable \&? 347command. 348.It Ic status 349Lists the current status of encryption. 350.It Ic stop Ic [input|output] 351Stops encryption. If you omit input and output, 352encryption is on both input and output. 353.It Ic type Ar type 354Sets the default type of encryption to be used 355with later 356.Ic encrypt start 357or 358.Ic encrypt stop 359commands. 360.El 361.It Ic environ Ar arguments... 362The 363.Ic environ 364command is used to manipulate the 365the variables that my be sent through the 366.Dv TELNET ENVIRON 367option. 368The initial set of variables is taken from the users 369environment, with only the 370.Ev DISPLAY 371and 372.Ev PRINTER 373variables being exported by default. 374The 375.Ev USER 376variable is also exported if the 377.Fl a 378or 379.Fl l 380options are used. 381.br 382Valid arguments for the 383.Ic environ 384command are: 385.Bl -tag -width Fl 386.It Ic define Ar variable value 387Define the variable 388.Ar variable 389to have a value of 390.Ar value. 391Any variables defined by this command are automatically exported. 392The 393.Ar value 394may be enclosed in single or double quotes so 395that tabs and spaces may be included. 396.It Ic undefine Ar variable 397Remove 398.Ar variable 399from the list of environment variables. 400.It Ic export Ar variable 401Mark the variable 402.Ar variable 403to be exported to the remote side. 404.It Ic unexport Ar variable 405Mark the variable 406.Ar variable 407to not be exported unless 408explicitly asked for by the remote side. 409.It Ic list 410List the current set of environment variables. 411Those marked with a 412.Cm * 413will be sent automatically, 414other variables will only be sent if explicitly requested. 415.It Ic \&? 416Prints out help information for the 417.Ic environ 418command. 419.El 420.It Ic logout 421Sends the 422.Dv TELNET LOGOUT 423option to the remote side. 424This command is similar to a 425.Ic close 426command; however, if the remote side does not support the 427.Dv LOGOUT 428option, nothing happens. 429If, however, the remote side does support the 430.Dv LOGOUT 431option, this command should cause the remote side to close the 432.Tn TELNET 433connection. 434If the remote side also supports the concept of 435suspending a user's session for later reattachment, 436the logout argument indicates that you 437should terminate the session immediately. 438.It Ic mode Ar type 439.Ar Type 440is one of several options, depending on the state of the 441.Tn TELNET 442session. 443The remote host is asked for permission to go into the requested mode. 444If the remote host is capable of entering that mode, the requested 445mode will be entered. 446.Bl -tag -width Ar 447.It Ic character 448Disable the 449.Dv TELNET LINEMODE 450option, or, if the remote side does not understand the 451.Dv LINEMODE 452option, then enter \*(Lqcharacter at a time\*(Lq mode. 453.It Ic line 454Enable the 455.Dv TELNET LINEMODE 456option, or, if the remote side does not understand the 457.Dv LINEMODE 458option, then attempt to enter \*(Lqold-line-by-line\*(Lq mode. 459.It Ic isig Pq Ic \-isig 460Attempt to enable (disable) the 461.Dv TRAPSIG 462mode of the 463.Dv LINEMODE 464option. 465This requires that the 466.Dv LINEMODE 467option be enabled. 468.It Ic edit Pq Ic \-edit 469Attempt to enable (disable) the 470.Dv EDIT 471mode of the 472.Dv LINEMODE 473option. 474This requires that the 475.Dv LINEMODE 476option be enabled. 477.It Ic softtabs Pq Ic \-softtabs 478Attempt to enable (disable) the 479.Dv SOFT_TAB 480mode of the 481.Dv LINEMODE 482option. 483This requires that the 484.Dv LINEMODE 485option be enabled. 486.ne 1i 487.It Ic litecho Pq Ic \-litecho 488Attempt to enable (disable) the 489.Dv LIT_ECHO 490mode of the 491.Dv LINEMODE 492option. 493This requires that the 494.Dv LINEMODE 495option be enabled. 496.It Ic \&? 497Prints out help information for the 498.Ic mode 499command. 500.El 501.It Xo 502.Ic open Ar host 503.Oo Op Fl l 504.Ar user 505.Oc Ns Oo Fl 506.Ar port Oc 507.Xc 508Open a connection to the named host. 509If no port number 510is specified, 511.Nm telnet 512will attempt to contact a 513.Tn TELNET 514server at the default port. 515The host specification may be either a host name (see 516.Xr hosts 5 ) 517or an Internet address specified in the \*(Lqdot notation\*(Rq (see 518.Xr inet 3 ) . 519The 520.Op Fl l 521option may be used to specify the user name 522to be passed to the remote system via the 523.Ev ENVIRON 524option. 525When connecting to a non-standard port, 526.Nm telnet 527omits any automatic initiation of 528.Tn TELNET 529options. When the port number is preceded by a minus sign, 530the initial option negotiation is done. 531After establishing a connection, the file 532.Pa \&.telnetrc 533in the 534users home directory is opened. Lines beginning with a # are 535comment lines. Blank lines are ignored. Lines that begin 536without white space are the start of a machine entry. The 537first thing on the line is the name of the machine that is 538being connected to. The rest of the line, and successive 539lines that begin with white space are assumed to be 540.Nm telnet 541commands and are processed as if they had been typed 542in manually to the 543.Nm telnet 544command prompt. 545.It Ic quit 546Close any open 547.Tn TELNET 548session and exit 549.Nm telnet . 550An end of file (in command mode) will also close a session and exit. 551.It Ic send Ar arguments 552Sends one or more special character sequences to the remote host. 553The following are the arguments which may be specified 554(more than one argument may be specified at a time): 555.Pp 556.Bl -tag -width escape 557.It Ic abort 558Sends the 559.Dv TELNET ABORT 560(Abort 561processes) 562sequence. 563.It Ic ao 564Sends the 565.Dv TELNET AO 566(Abort Output) sequence, which should cause the remote system to flush 567all output 568.Em from 569the remote system 570.Em to 571the user's terminal. 572.It Ic ayt 573Sends the 574.Dv TELNET AYT 575(Are You There) 576sequence, to which the remote system may or may not choose to respond. 577.It Ic brk 578Sends the 579.Dv TELNET BRK 580(Break) sequence, which may have significance to the remote 581system. 582.It Ic ec 583Sends the 584.Dv TELNET EC 585(Erase Character) 586sequence, which should cause the remote system to erase the last character 587entered. 588.It Ic el 589Sends the 590.Dv TELNET EL 591(Erase Line) 592sequence, which should cause the remote system to erase the line currently 593being entered. 594.It Ic eof 595Sends the 596.Dv TELNET EOF 597(End Of File) 598sequence. 599.It Ic eor 600Sends the 601.Dv TELNET EOR 602(End of Record) 603sequence. 604.It Ic escape 605Sends the current 606.Nm telnet 607escape character (initially \*(Lq^\*(Rq). 608.It Ic ga 609Sends the 610.Dv TELNET GA 611(Go Ahead) 612sequence, which likely has no significance to the remote system. 613.It Ic getstatus 614If the remote side supports the 615.Dv TELNET STATUS 616command, 617.Ic getstatus 618will send the subnegotiation to request that the server send 619its current option status. 620.ne 1i 621.It Ic ip 622Sends the 623.Dv TELNET IP 624(Interrupt Process) sequence, which should cause the remote 625system to abort the currently running process. 626.It Ic nop 627Sends the 628.Dv TELNET NOP 629(No OPeration) 630sequence. 631.It Ic susp 632Sends the 633.Dv TELNET SUSP 634(SUSPend process) 635sequence. 636.It Ic synch 637Sends the 638.Dv TELNET SYNCH 639sequence. 640This sequence causes the remote system to discard all previously typed 641(but not yet read) input. 642This sequence is sent as 643.Tn TCP 644urgent 645data (and may not work if the remote system is a 646.Bx 4.2 647system -- if 648it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal). 649.It Ic do Ar cmd 650.It Ic dont Ar cmd 651.It Ic will Ar cmd 652.It Ic wont Ar cmd 653Sends the 654.Dv TELNET DO 655.Ar cmd 656sequence. 657.Ar Cmd 658can be either a decimal number between 0 and 255, 659or a symbolic name for a specific 660.Dv TELNET 661command. 662.Ar Cmd 663can also be either 664.Ic help 665or 666.Ic \&? 667to print out help information, including 668a list of known symbolic names. 669.It Ic \&? 670Prints out help information for the 671.Ic send 672command. 673.El 674.It Ic set Ar argument value 675.It Ic unset Ar argument value 676The 677.Ic set 678command will set any one of a number of 679.Nm telnet 680variables to a specific value or to 681.Dv TRUE . 682The special value 683.Ic off 684turns off the function associated with 685the variable, this is equivalent to using the 686.Ic unset 687command. 688The 689.Ic unset 690command will disable or set to 691.Dv FALSE 692any of the specified functions. 693The values of variables may be interrogated with the 694.Ic display 695command. 696The variables which may be set or unset, but not toggled, are 697listed here. In addition, any of the variables for the 698.Ic toggle 699command may be explicitly set or unset using 700the 701.Ic set 702and 703.Ic unset 704commands. 705.Bl -tag -width escape 706.It Ic ayt 707If 708.Tn TELNET 709is in localchars mode, or 710.Dv LINEMODE 711is enabled, and the status character is typed, a 712.Dv TELNET AYT 713sequence (see 714.Ic send ayt 715preceding) is sent to the 716remote host. The initial value for the "Are You There" 717character is the terminal's status character. 718.It Ic echo 719This is the value (initially \*(Lq^E\*(Rq) which, when in 720\*(Lqline by line\*(Rq mode, toggles between doing local echoing 721of entered characters (for normal processing), and suppressing 722echoing of entered characters (for entering, say, a password). 723.It Ic eof 724If 725.Nm telnet 726is operating in 727.Dv LINEMODE 728or \*(Lqold line by line\*(Rq mode, entering this character 729as the first character on a line will cause this character to be 730sent to the remote system. 731The initial value of the eof character is taken to be the terminal's 732.Ic eof 733character. 734.It Ic erase 735If 736.Nm telnet 737is in 738.Ic localchars 739mode (see 740.Ic toggle 741.Ic localchars 742below), 743.Sy and 744if 745.Nm telnet 746is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 747character is typed, a 748.Dv TELNET EC 749sequence (see 750.Ic send 751.Ic ec 752above) 753is sent to the remote system. 754The initial value for the erase character is taken to be 755the terminal's 756.Ic erase 757character. 758.It Ic escape 759This is the 760.Nm telnet 761escape character (initially \*(Lq^[\*(Rq) which causes entry 762into 763.Nm telnet 764command mode (when connected to a remote system). 765.It Ic flushoutput 766If 767.Nm telnet 768is in 769.Ic localchars 770mode (see 771.Ic toggle 772.Ic localchars 773below) 774and the 775.Ic flushoutput 776character is typed, a 777.Dv TELNET AO 778sequence (see 779.Ic send 780.Ic ao 781above) 782is sent to the remote host. 783The initial value for the flush character is taken to be 784the terminal's 785.Ic flush 786character. 787.It Ic forw1 788.It Ic forw2 789If 790.Tn TELNET 791is operating in 792.Dv LINEMODE , 793these are the 794characters that, when typed, cause partial lines to be 795forwarded to the remote system. The initial value for 796the forwarding characters are taken from the terminal's 797eol and eol2 characters. 798.It Ic interrupt 799If 800.Nm telnet 801is in 802.Ic localchars 803mode (see 804.Ic toggle 805.Ic localchars 806below) 807and the 808.Ic interrupt 809character is typed, a 810.Dv TELNET IP 811sequence (see 812.Ic send 813.Ic ip 814above) 815is sent to the remote host. 816The initial value for the interrupt character is taken to be 817the terminal's 818.Ic intr 819character. 820.It Ic kill 821If 822.Nm telnet 823is in 824.Ic localchars 825mode (see 826.Ic toggle 827.Ic localchars 828below), 829.Ic and 830if 831.Nm telnet 832is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 833character is typed, a 834.Dv TELNET EL 835sequence (see 836.Ic send 837.Ic el 838above) 839is sent to the remote system. 840The initial value for the kill character is taken to be 841the terminal's 842.Ic kill 843character. 844.It Ic lnext 845If 846.Nm telnet 847is operating in 848.Dv LINEMODE 849or \*(Lqold line by line\*(Lq mode, then this character is taken to 850be the terminal's 851.Ic lnext 852character. 853The initial value for the lnext character is taken to be 854the terminal's 855.Ic lnext 856character. 857.It Ic quit 858If 859.Nm telnet 860is in 861.Ic localchars 862mode (see 863.Ic toggle 864.Ic localchars 865below) 866and the 867.Ic quit 868character is typed, a 869.Dv TELNET BRK 870sequence (see 871.Ic send 872.Ic brk 873above) 874is sent to the remote host. 875The initial value for the quit character is taken to be 876the terminal's 877.Ic quit 878character. 879.It Ic reprint 880If 881.Nm telnet 882is operating in 883.Dv LINEMODE 884or \*(Lqold line by line\*(Lq mode, then this character is taken to 885be the terminal's 886.Ic reprint 887character. 888The initial value for the reprint character is taken to be 889the terminal's 890.Ic reprint 891character. 892.It Ic rlogin 893This is the rlogin escape character. 894If set, the normal 895.Tn TELNET 896escape character is ignored unless it is 897preceded by this character at the beginning of a line. 898This character, at the beginning of a line followed by 899a "." closes the connection; when followed by a ^Z it 900suspends the telnet command. The initial state is to 901disable the rlogin escape character. 902.It Ic start 903If the 904.Dv TELNET TOGGLE-FLOW-CONTROL 905option has been enabled, 906then this character is taken to 907be the terminal's 908.Ic start 909character. 910The initial value for the kill character is taken to be 911the terminal's 912.Ic start 913character. 914.It Ic stop 915If the 916.Dv TELNET TOGGLE-FLOW-CONTROL 917option has been enabled, 918then this character is taken to 919be the terminal's 920.Ic stop 921character. 922The initial value for the kill character is taken to be 923the terminal's 924.Ic stop 925character. 926.It Ic susp 927If 928.Nm telnet 929is in 930.Ic localchars 931mode, or 932.Dv LINEMODE 933is enabled, and the 934.Ic suspend 935character is typed, a 936.Dv TELNET SUSP 937sequence (see 938.Ic send 939.Ic susp 940above) 941is sent to the remote host. 942The initial value for the suspend character is taken to be 943the terminal's 944.Ic suspend 945character. 946.ne 1i 947.It Ic tracefile 948This is the file to which the output, caused by 949.Ic netdata 950or 951.Ic option 952tracing being 953.Dv TRUE , 954will be written. If it is set to 955.Dq Fl , 956then tracing information will be written to standard output (the default). 957.It Ic worderase 958If 959.Nm telnet 960is operating in 961.Dv LINEMODE 962or \*(Lqold line by line\*(Lq mode, then this character is taken to 963be the terminal's 964.Ic worderase 965character. 966The initial value for the worderase character is taken to be 967the terminal's 968.Ic worderase 969character. 970.It Ic \&? 971Displays the legal 972.Ic set 973.Pq Ic unset 974commands. 975.El 976.It Ic slc Ar state 977The 978.Ic slc 979command (Set Local Characters) is used to set 980or change the state of the the special 981characters when the 982.Dv TELNET LINEMODE 983option has 984been enabled. Special characters are characters that get 985mapped to 986.Tn TELNET 987commands sequences (like 988.Ic ip 989or 990.Ic quit ) 991or line editing characters (like 992.Ic erase 993and 994.Ic kill ) . 995By default, the local special characters are exported. 996.Bl -tag -width Fl 997.It Ic check 998Verify the current settings for the current special characters. 999The remote side is requested to send all the current special 1000character settings, and if there are any discrepancies with 1001the local side, the local side will switch to the remote value. 1002.It Ic export 1003Switch to the local defaults for the special characters. The 1004local default characters are those of the local terminal at 1005the time when 1006.Nm telnet 1007was started. 1008.It Ic import 1009Switch to the remote defaults for the special characters. 1010The remote default characters are those of the remote system 1011at the time when the 1012.Tn TELNET 1013connection was established. 1014.It Ic \&? 1015Prints out help information for the 1016.Ic slc 1017command. 1018.El 1019.It Ic status 1020Show the current status of 1021.Nm telnet . 1022This includes the peer one is connected to, as well 1023as the current mode. 1024.It Ic toggle Ar arguments ... 1025Toggle (between 1026.Dv TRUE 1027and 1028.Dv FALSE ) 1029various flags that control how 1030.Nm telnet 1031responds to events. 1032These flags may be set explicitly to 1033.Dv TRUE 1034or 1035.Dv FALSE 1036using the 1037.Ic set 1038and 1039.Ic unset 1040commands listed above. 1041More than one argument may be specified. 1042The state of these flags may be interrogated with the 1043.Ic display 1044command. 1045Valid arguments are: 1046.Bl -tag -width Ar 1047.It Ic authdebug 1048Turns on debugging information for the authentication code. 1049.It Ic autoflush 1050If 1051.Ic autoflush 1052and 1053.Ic localchars 1054are both 1055.Dv TRUE , 1056then when the 1057.Ic ao , 1058or 1059.Ic quit 1060characters are recognized (and transformed into 1061.Tn TELNET 1062sequences; see 1063.Ic set 1064above for details), 1065.Nm telnet 1066refuses to display any data on the user's terminal 1067until the remote system acknowledges (via a 1068.Dv TELNET TIMING MARK 1069option) 1070that it has processed those 1071.Tn TELNET 1072sequences. 1073The initial value for this toggle is 1074.Dv TRUE 1075if the terminal user had not 1076done an "stty noflsh", otherwise 1077.Dv FALSE 1078(see 1079.Xr stty 1 ) . 1080.It Ic autodecrypt 1081When the 1082.Dv TELNET ENCRYPT 1083option is negotiated, by 1084default the actual encryption (decryption) of the data 1085stream does not start automatically. The autoencrypt 1086(autodecrypt) command states that encryption of the 1087output (input) stream should be enabled as soon as 1088possible. 1089.sp 1090.Pp 1091Note: Because of export controls, the 1092.Dv TELNET ENCRYPT 1093option is not supported outside the United States and Canada. 1094.It Ic autologin 1095If the remote side supports the 1096.Dv TELNET AUTHENTICATION 1097option 1098.Tn TELNET 1099attempts to use it to perform automatic authentication. If the 1100.Dv AUTHENTICATION 1101option is not supported, the user's login 1102name are propagated through the 1103.Dv TELNET ENVIRON 1104option. 1105This command is the same as specifying 1106.Ar a 1107option on the 1108.Ic open 1109command. 1110.It Ic autosynch 1111If 1112.Ic autosynch 1113and 1114.Ic localchars 1115are both 1116.Dv TRUE , 1117then when either the 1118.Ic intr 1119or 1120.Ic quit 1121characters is typed (see 1122.Ic set 1123above for descriptions of the 1124.Ic intr 1125and 1126.Ic quit 1127characters), the resulting 1128.Tn TELNET 1129sequence sent is followed by the 1130.Dv TELNET SYNCH 1131sequence. 1132This procedure 1133.Ic should 1134cause the remote system to begin throwing away all previously 1135typed input until both of the 1136.Tn TELNET 1137sequences have been read and acted upon. 1138The initial value of this toggle is 1139.Dv FALSE . 1140.It Ic binary 1141Enable or disable the 1142.Dv TELNET BINARY 1143option on both input and output. 1144.It Ic inbinary 1145Enable or disable the 1146.Dv TELNET BINARY 1147option on input. 1148.It Ic outbinary 1149Enable or disable the 1150.Dv TELNET BINARY 1151option on output. 1152.It Ic crlf 1153If this is 1154.Dv TRUE , 1155then carriage returns will be sent as 1156.Li <CR><LF> . 1157If this is 1158.Dv FALSE , 1159then carriage returns will be send as 1160.Li <CR><NUL> . 1161The initial value for this toggle is 1162.Dv FALSE . 1163.It Ic crmod 1164Toggle carriage return mode. 1165When this mode is enabled, most carriage return characters received from 1166the remote host will be mapped into a carriage return followed by 1167a line feed. 1168This mode does not affect those characters typed by the user, only 1169those received from the remote host. 1170This mode is not very useful unless the remote host 1171only sends carriage return, but never line feed. 1172The initial value for this toggle is 1173.Dv FALSE . 1174.It Ic debug 1175Toggles socket level debugging (useful only to the 1176.Ic super user ) . 1177The initial value for this toggle is 1178.Dv FALSE . 1179.It Ic encdebug 1180Turns on debugging information for the encryption code. 1181.It Ic localchars 1182If this is 1183.Dv TRUE , 1184then the 1185.Ic flush , 1186.Ic interrupt , 1187.Ic quit , 1188.Ic erase , 1189and 1190.Ic kill 1191characters (see 1192.Ic set 1193above) are recognized locally, and transformed into (hopefully) appropriate 1194.Tn TELNET 1195control sequences 1196(respectively 1197.Ic ao , 1198.Ic ip , 1199.Ic brk , 1200.Ic ec , 1201and 1202.Ic el ; 1203see 1204.Ic send 1205above). 1206The initial value for this toggle is 1207.Dv TRUE 1208in \*(Lqold line by line\*(Rq mode, 1209and 1210.Dv FALSE 1211in \*(Lqcharacter at a time\*(Rq mode. 1212When the 1213.Dv LINEMODE 1214option is enabled, the value of 1215.Ic localchars 1216is ignored, and assumed to always be 1217.Dv TRUE . 1218If 1219.Dv LINEMODE 1220has ever been enabled, then 1221.Ic quit 1222is sent as 1223.Ic abort , 1224and 1225.Ic eof and 1226.B suspend 1227are sent as 1228.Ic eof and 1229.Ic susp , 1230see 1231.Ic send 1232above). 1233.It Ic netdata 1234Toggles the display of all network data (in hexadecimal format). 1235The initial value for this toggle is 1236.Dv FALSE . 1237.It Ic options 1238Toggles the display of some internal 1239.Nm telnet 1240protocol processing (having to do with 1241.Tn TELNET 1242options). 1243The initial value for this toggle is 1244.Dv FALSE . 1245.ne 1i 1246.It Ic prettydump 1247When the 1248.Ic netdata 1249toggle is enabled, if 1250.Ic prettydump 1251is enabled the output from the 1252.Ic netdata 1253command will be formatted in a more user readable format. 1254Spaces are put between each character in the output, and the 1255beginning of any 1256.Tn TELNET 1257escape sequence is preceded by a '*' to aid in locating them. 1258.It Ic skiprc 1259When the skiprc toggle is 1260.Dv TRUE , 1261.Tn TELNET 1262skips the reading of the 1263.Pa \&.telnetrc 1264file in the users home 1265directory when connections are opened. The initial 1266value for this toggle is 1267.Dv FALSE. 1268.It Ic termdata 1269Toggles the display of all terminal data (in hexadecimal format). 1270The initial value for this toggle is 1271.Dv FALSE . 1272.It Ic verbose_encrypt 1273When the 1274.Ic verbose_encrypt 1275toggle is 1276.Dv TRUE , 1277.Tn TELNET 1278prints out a message each time encryption is enabled or 1279disabled. The initial value for this toggle is 1280.Dv FALSE. 1281Note: Because of export controls, data encryption 1282is not supported outside of the United States and Canada. 1283.It Ic \&? 1284Displays the legal 1285.Ic toggle 1286commands. 1287.El 1288.It Ic z 1289Suspend 1290.Nm telnet . 1291This command only works when the user is using the 1292.Xr csh 1 . 1293.It Ic \&! Op Ar command 1294Execute a single command in a subshell on the local 1295system. If 1296.Ic command 1297is omitted, then an interactive 1298subshell is invoked. 1299.It Ic \&? Op Ar command 1300Get help. With no arguments, 1301.Nm telnet 1302prints a help summary. 1303If a command is specified, 1304.Nm telnet 1305will print the help information for just that command. 1306.El 1307.Sh ENVIRONMENT 1308.Nm Telnet 1309uses at least the 1310.Ev HOME , 1311.Ev SHELL , 1312.Ev DISPLAY , 1313and 1314.Ev TERM 1315environment variables. 1316Other environment variables may be propagated 1317to the other side via the 1318.Dv TELNET ENVIRON 1319option. 1320.Sh FILES 1321.Bl -tag -width ~/.telnetrc -compact 1322.It Pa ~/.telnetrc 1323user customized telnet startup values 1324.El 1325.Sh HISTORY 1326The 1327.Nm Telnet 1328command appeared in 1329.Bx 4.2 . 1330.Sh NOTES 1331.Pp 1332On some remote systems, echo has to be turned off manually when in 1333\*(Lqold line by line\*(Rq mode. 1334.Pp 1335In \*(Lqold line by line\*(Rq mode or 1336.Dv LINEMODE 1337the terminal's 1338.Ic eof 1339character is only recognized (and sent to the remote system) 1340when it is the first character on a line. 1341