1.\" Copyright (c) 1983, 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)telnet.1 8.6 (Berkeley) 6/1/94 33.\" $FreeBSD: src/crypto/telnet/telnet/telnet.1,v 1.4.2.9 2002/04/13 10:59:08 markm Exp $ 34.\" $DragonFly: src/crypto/telnet/telnet/telnet.1,v 1.2 2003/06/17 04:24:37 dillon Exp $ 35.\" 36.Dd August 26, 2009 37.Dt TELNET 1 38.Os 39.Sh NAME 40.Nm telnet 41.Nd user interface to the 42.Tn TELNET 43protocol 44.Sh SYNOPSIS 45.Nm 46.Op Fl 468EFKLNacdfruxy 47.Op Fl S Ar tos 48.Op Fl X Ar authtype 49.Op Fl e Ar escapechar 50.Op Fl k Ar realm 51.Op Fl l Ar user 52.Op Fl n Ar tracefile 53.Op Fl s Ar src_addr 54.Oo 55.Ar host 56.Op Ar port 57.Oc 58.Sh DESCRIPTION 59The 60.Nm 61command 62is used to communicate with another host using the 63.Tn TELNET 64protocol. 65If 66.Nm 67is invoked without the 68.Ar host 69argument, it enters command mode, 70indicated by its prompt 71.Pq Dq Li telnet\&> . 72In this mode, it accepts and executes the commands listed below. 73If it is invoked with arguments, it performs an 74.Ic open 75command with those arguments. 76.Pp 77Options: 78.Bl -tag -width indent 79.It Fl 4 80Forces 81.Nm 82to use IPv4 addresses only. 83.It Fl 6 84Forces 85.Nm 86to use IPv6 addresses only. 87.It Fl 8 88Specifies an 8-bit data path. This causes an attempt to 89negotiate the 90.Dv TELNET BINARY 91option on both input and output. 92.It Fl E 93Stops any character from being recognized as an escape character. 94.It Fl F 95If Kerberos V5 authentication is being used, the 96.Fl F 97option allows the local credentials to be forwarded 98to the remote system, including any credentials that 99have already been forwarded into the local environment. 100.It Fl K 101Specifies no automatic login to the remote system. 102This is now the default, so this option is ignored. 103.It Fl L 104Specifies an 8-bit data path on output. This causes the 105.Dv BINARY 106option to be negotiated on output. 107.It Fl N 108Prevents IP address to name lookup when destination host is given 109as an IP address. 110.It Fl S Ar tos 111Sets the IP type-of-service (TOS) option for the telnet 112connection to the value 113.Ar tos , 114which can be a numeric TOS value 115or, on systems that support it, a symbolic 116TOS name found in the 117.Pa /etc/iptos 118file. 119.It Fl X Ar atype 120Disables the 121.Ar atype 122type of authentication. 123.It Fl a 124Attempt automatic login. 125Currently, this sends the user name via the 126.Ev USER 127variable 128of the 129.Ev ENVIRON 130option if supported by the remote system. 131The name used is that of the current user as returned by 132.Xr getlogin 2 133if it agrees with the current user ID, 134otherwise it is the name associated with the user ID. 135.It Fl c 136Disables the reading of the user's 137.Pa \&.telnetrc 138file. (See the 139.Ic toggle skiprc 140command on this man page.) 141.It Fl d 142Sets the initial value of the 143.Ic debug 144toggle to 145.Dv TRUE . 146.It Fl e Ar escapechar 147Sets the initial 148.Nm 149escape character to 150.Ar escapechar . 151If 152.Ar escapechar 153is omitted, then 154there will be no escape character. 155.It Fl f 156If Kerberos V5 authentication is being used, the 157.Fl f 158option allows the local credentials to be forwarded to the remote system. 159.It Fl k Ar realm 160If Kerberos authentication is being used, the 161.Fl k 162option requests that 163.Nm 164obtain tickets for the remote host in 165realm 166.Ar realm 167instead of the remote host's realm, as determined by 168.Xr krb_realmofhost 3 . 169.It Fl l Ar user 170When connecting to the remote system, if the remote system 171understands the 172.Ev ENVIRON 173option, then 174.Ar user 175will be sent to the remote system as the value for the variable 176.Ev USER . 177This option implies the 178.Fl a 179option. 180This option may also be used with the 181.Ic open 182command. 183.It Fl n Ar tracefile 184Opens 185.Ar tracefile 186for recording trace information. 187See the 188.Ic set tracefile 189command below. 190.It Fl r 191Specifies a user interface similar to 192.Xr rlogin 1 . 193In this 194mode, the escape character is set to the tilde (~) character, 195unless modified by the 196.Fl e 197option. 198.It Fl s Ar src_addr 199Set the source IP address for the 200.Nm 201connection to 202.Ar src_addr , 203which can be an IP address or a host name. 204.It Fl u 205Forces 206.Nm 207to use 208.Dv AF_UNIX 209addresses only (e.g., 210.Ux 211domain sockets, accessed with a file path). 212.It Fl x 213Turns on encryption of the data stream if possible. 214This is now the default, so this option is ignored. 215.It Fl y 216Suppresses encryption of the data stream. 217.It Ar host 218Indicates the official name, an alias, or the Internet address 219of a remote host. 220If 221.Ar host 222starts with a 223.Ql / , 224.Nm 225establishes a connection to the corresponding named socket. 226.It Ar port 227Indicates a port number (address of an application). If a number is 228not specified, the default 229.Nm 230port is used. 231.El 232.Pp 233When in rlogin mode, a line of the form ~. disconnects from the 234remote host; ~ is the 235.Nm 236escape character. 237Similarly, the line ~^Z suspends the 238.Nm 239session. 240The line ~^] escapes to the normal 241.Nm 242escape prompt. 243.Pp 244Once a connection has been opened, 245.Nm 246will attempt to enable the 247.Dv TELNET LINEMODE 248option. 249If this fails, then 250.Nm 251will revert to one of two input modes: 252either \*(Lqcharacter at a time\*(Rq 253or \*(Lqold line by line\*(Rq 254depending on what the remote system supports. 255.Pp 256When 257.Dv LINEMODE 258is enabled, character processing is done on the 259local system, under the control of the remote system. When input 260editing or character echoing is to be disabled, the remote system 261will relay that information. The remote system will also relay 262changes to any special characters that happen on the remote 263system, so that they can take effect on the local system. 264.Pp 265In \*(Lqcharacter at a time\*(Rq mode, most 266text typed is immediately sent to the remote host for processing. 267.Pp 268In \*(Lqold line by line\*(Rq mode, all text is echoed locally, 269and (normally) only completed lines are sent to the remote host. 270The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used 271to turn off and on the local echo 272(this would mostly be used to enter passwords 273without the password being echoed). 274.Pp 275If the 276.Dv LINEMODE 277option is enabled, or if the 278.Ic localchars 279toggle is 280.Dv TRUE 281(the default for \*(Lqold line by line\*(Rq; see below), 282the user's 283.Ic quit , 284.Ic intr , 285and 286.Ic flush 287characters are trapped locally, and sent as 288.Tn TELNET 289protocol sequences to the remote side. 290If 291.Dv LINEMODE 292has ever been enabled, then the user's 293.Ic susp 294and 295.Ic eof 296are also sent as 297.Tn TELNET 298protocol sequences, 299and 300.Ic quit 301is sent as a 302.Dv TELNET ABORT 303instead of 304.Dv BREAK . 305There are options (see 306.Ic toggle 307.Ic autoflush 308and 309.Ic toggle 310.Ic autosynch 311below) 312which cause this action to flush subsequent output to the terminal 313(until the remote host acknowledges the 314.Tn TELNET 315sequence) and flush previous terminal input 316(in the case of 317.Ic quit 318and 319.Ic intr ) . 320.Pp 321While connected to a remote host, 322.Nm 323command mode may be entered by typing the 324.Nm 325\*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq). 326When in command mode, the normal terminal editing conventions are available. 327.Pp 328The following 329.Nm 330commands are available. 331Only enough of each command to uniquely identify it need be typed 332(this is also true for arguments to the 333.Ic mode , 334.Ic set , 335.Ic toggle , 336.Ic unset , 337.Ic slc , 338.Ic environ , 339and 340.Ic display 341commands). 342.Bl -tag -width "mode type" 343.It Ic auth Ar argument ... 344The auth command manipulates the information sent through the 345.Dv TELNET AUTHENTICATE 346option. Valid arguments for the 347.Ic auth 348command are: 349.Bl -tag -width "disable type" 350.It Ic disable Ar type 351Disables the specified type of authentication. To 352obtain a list of available types, use the 353.Ic auth disable ?\& 354command. 355.It Ic enable Ar type 356Enables the specified type of authentication. To 357obtain a list of available types, use the 358.Ic auth enable ?\& 359command. 360.It Ic status 361Lists the current status of the various types of 362authentication. 363.El 364.It Ic close 365Close a 366.Tn TELNET 367session and return to command mode. 368.It Ic display Ar argument ... 369Displays all, or some, of the 370.Ic set 371and 372.Ic toggle 373values (see below). 374.It Ic encrypt Ar argument ... 375The encrypt command manipulates the information sent through the 376.Dv TELNET ENCRYPT 377option. 378.Pp 379Valid arguments for the 380.Ic encrypt 381command are: 382.Bl -tag -width Ar 383.It Ic disable Ar type Xo 384.Op Cm input | output 385.Xc 386Disables the specified type of encryption. If you 387omit the input and output, both input and output 388are disabled. To obtain a list of available 389types, use the 390.Ic encrypt disable ?\& 391command. 392.It Ic enable Ar type Xo 393.Op Cm input | output 394.Xc 395Enables the specified type of encryption. If you 396omit input and output, both input and output are 397enabled. To obtain a list of available types, use the 398.Ic encrypt enable ?\& 399command. 400.It Ic input 401This is the same as the 402.Ic encrypt start input 403command. 404.It Ic -input 405This is the same as the 406.Ic encrypt stop input 407command. 408.It Ic output 409This is the same as the 410.Ic encrypt start output 411command. 412.It Ic -output 413This is the same as the 414.Ic encrypt stop output 415command. 416.It Ic start Op Cm input | output 417Attempts to start encryption. If you omit 418.Ic input 419and 420.Ic output , 421both input and output are enabled. To 422obtain a list of available types, use the 423.Ic encrypt enable ?\& 424command. 425.It Ic status 426Lists the current status of encryption. 427.It Ic stop Op Cm input | output 428Stops encryption. If you omit input and output, 429encryption is on both input and output. 430.It Ic type Ar type 431Sets the default type of encryption to be used 432with later 433.Ic encrypt start 434or 435.Ic encrypt stop 436commands. 437.El 438.It Ic environ Ar arguments ... 439The 440.Ic environ 441command is used to manipulate the 442variables that may be sent through the 443.Dv TELNET ENVIRON 444option. 445The initial set of variables is taken from the users 446environment, with only the 447.Ev DISPLAY 448and 449.Ev PRINTER 450variables being exported by default. 451The 452.Ev USER 453variable is also exported if the 454.Fl a 455or 456.Fl l 457options are used. 458.Pp 459Valid arguments for the 460.Ic environ 461command are: 462.Bl -tag -width Fl 463.It Ic define Ar variable value 464Define the variable 465.Ar variable 466to have a value of 467.Ar value . 468Any variables defined by this command are automatically exported. 469The 470.Ar value 471may be enclosed in single or double quotes so 472that tabs and spaces may be included. 473.It Ic undefine Ar variable 474Remove 475.Ar variable 476from the list of environment variables. 477.It Ic export Ar variable 478Mark the variable 479.Ar variable 480to be exported to the remote side. 481.It Ic unexport Ar variable 482Mark the variable 483.Ar variable 484to not be exported unless 485explicitly asked for by the remote side. 486.It Ic list 487List the current set of environment variables. 488Those marked with a 489.Cm * 490will be sent automatically, 491other variables will only be sent if explicitly requested. 492.It Ic ?\& 493Prints out help information for the 494.Ic environ 495command. 496.El 497.It Ic logout 498Sends the 499.Dv TELNET LOGOUT 500option to the remote side. 501This command is similar to a 502.Ic close 503command; however, if the remote side does not support the 504.Dv LOGOUT 505option, nothing happens. 506If, however, the remote side does support the 507.Dv LOGOUT 508option, this command should cause the remote side to close the 509.Tn TELNET 510connection. 511If the remote side also supports the concept of 512suspending a user's session for later reattachment, 513the logout argument indicates that you 514should terminate the session immediately. 515.It Ic mode Ar type 516.Ar Type 517is one of several options, depending on the state of the 518.Tn TELNET 519session. 520The remote host is asked for permission to go into the requested mode. 521If the remote host is capable of entering that mode, the requested 522mode will be entered. 523.Bl -tag -width Ar 524.It Ic character 525Disable the 526.Dv TELNET LINEMODE 527option, or, if the remote side does not understand the 528.Dv LINEMODE 529option, then enter \*(Lqcharacter at a time\*(Rq mode. 530.It Ic line 531Enable the 532.Dv TELNET LINEMODE 533option, or, if the remote side does not understand the 534.Dv LINEMODE 535option, then attempt to enter \*(Lqold-line-by-line\*(Rq mode. 536.It Ic isig Pq Ic \-isig 537Attempt to enable (disable) the 538.Dv TRAPSIG 539mode of the 540.Dv LINEMODE 541option. 542This requires that the 543.Dv LINEMODE 544option be enabled. 545.It Ic edit Pq Ic \-edit 546Attempt to enable (disable) the 547.Dv EDIT 548mode of the 549.Dv LINEMODE 550option. 551This requires that the 552.Dv LINEMODE 553option be enabled. 554.It Ic softtabs Pq Ic \-softtabs 555Attempt to enable (disable) the 556.Dv SOFT_TAB 557mode of the 558.Dv LINEMODE 559option. 560This requires that the 561.Dv LINEMODE 562option be enabled. 563.It Ic litecho Pq Ic \-litecho 564Attempt to enable (disable) the 565.Dv LIT_ECHO 566mode of the 567.Dv LINEMODE 568option. 569This requires that the 570.Dv LINEMODE 571option be enabled. 572.It Ic ?\& 573Prints out help information for the 574.Ic mode 575command. 576.El 577.It Xo 578.Ic open Ar host 579.Op Fl l Ar user 580.Op Oo Fl Oc Ns Ar port 581.Xc 582Open a connection to the named host. 583If no port number 584is specified, 585.Nm 586will attempt to contact a 587.Tn TELNET 588server at the default port. 589The host specification may be either a host name (see 590.Xr hosts 5 ) , 591an Internet address specified in the \*(Lqdot notation\*(Rq (see 592.Xr inet 3 ) , 593or IPv6 host name or IPv6 coloned-hexadecimal address. 594The 595.Fl l 596option may be used to specify the user name 597to be passed to the remote system via the 598.Ev ENVIRON 599option. 600When connecting to a non-standard port, 601.Nm 602omits any automatic initiation of 603.Tn TELNET 604options. When the port number is preceded by a minus sign, 605the initial option negotiation is done. 606After establishing a connection, the file 607.Pa \&.telnetrc 608in the 609users home directory is opened. Lines beginning with a # are 610comment lines. Blank lines are ignored. Lines that begin 611without white space are the start of a machine entry. The 612first thing on the line is the name of the machine that is 613being connected to. The rest of the line, and successive 614lines that begin with white space are assumed to be 615.Nm 616commands and are processed as if they had been typed 617in manually to the 618.Nm 619command prompt. 620.It Ic quit 621Close any open 622.Tn TELNET 623session and exit 624.Nm . 625An end of file (in command mode) will also close a session and exit. 626.It Ic send Ar arguments 627Sends one or more special character sequences to the remote host. 628The following are the arguments which may be specified 629(more than one argument may be specified at a time): 630.Bl -tag -width escape 631.It Ic abort 632Sends the 633.Dv TELNET ABORT 634(Abort 635processes) 636sequence. 637.It Ic ao 638Sends the 639.Dv TELNET AO 640(Abort Output) sequence, which should cause the remote system to flush 641all output 642.Em from 643the remote system 644.Em to 645the user's terminal. 646.It Ic ayt 647Sends the 648.Dv TELNET AYT 649(Are You There) 650sequence, to which the remote system may or may not choose to respond. 651.It Ic brk 652Sends the 653.Dv TELNET BRK 654(Break) sequence, which may have significance to the remote 655system. 656.It Ic ec 657Sends the 658.Dv TELNET EC 659(Erase Character) 660sequence, which should cause the remote system to erase the last character 661entered. 662.It Ic el 663Sends the 664.Dv TELNET EL 665(Erase Line) 666sequence, which should cause the remote system to erase the line currently 667being entered. 668.It Ic eof 669Sends the 670.Dv TELNET EOF 671(End Of File) 672sequence. 673.It Ic eor 674Sends the 675.Dv TELNET EOR 676(End of Record) 677sequence. 678.It Ic escape 679Sends the current 680.Nm 681escape character (initially \*(Lq^\*(Rq). 682.It Ic ga 683Sends the 684.Dv TELNET GA 685(Go Ahead) 686sequence, which likely has no significance to the remote system. 687.It Ic getstatus 688If the remote side supports the 689.Dv TELNET STATUS 690command, 691.Ic getstatus 692will send the subnegotiation to request that the server send 693its current option status. 694.It Ic ip 695Sends the 696.Dv TELNET IP 697(Interrupt Process) sequence, which should cause the remote 698system to abort the currently running process. 699.It Ic nop 700Sends the 701.Dv TELNET NOP 702(No OPeration) 703sequence. 704.It Ic susp 705Sends the 706.Dv TELNET SUSP 707(SUSPend process) 708sequence. 709.It Ic synch 710Sends the 711.Dv TELNET SYNCH 712sequence. 713This sequence causes the remote system to discard all previously typed 714(but not yet read) input. 715This sequence is sent as 716.Tn TCP 717urgent 718data (and may not work if the remote system is a 719.Bx 4.2 720system -- if 721it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal). 722.It Ic do Ar cmd 723.It Ic dont Ar cmd 724.It Ic will Ar cmd 725.It Ic wont Ar cmd 726Sends the 727.Dv TELNET DO 728.Ar cmd 729sequence. 730.Ar Cmd 731can be either a decimal number between 0 and 255, 732or a symbolic name for a specific 733.Dv TELNET 734command. 735.Ar Cmd 736can also be either 737.Ic help 738or 739.Ic ?\& 740to print out help information, including 741a list of known symbolic names. 742.It Ic ?\& 743Prints out help information for the 744.Ic send 745command. 746.El 747.It Ic set Ar argument value 748.It Ic unset Ar argument value 749The 750.Ic set 751command will set any one of a number of 752.Nm 753variables to a specific value or to 754.Dv TRUE . 755The special value 756.Ic off 757turns off the function associated with 758the variable, this is equivalent to using the 759.Ic unset 760command. 761The 762.Ic unset 763command will disable or set to 764.Dv FALSE 765any of the specified functions. 766The values of variables may be interrogated with the 767.Ic display 768command. 769The variables which may be set or unset, but not toggled, are 770listed here. In addition, any of the variables for the 771.Ic toggle 772command may be explicitly set or unset using 773the 774.Ic set 775and 776.Ic unset 777commands. 778.Bl -tag -width escape 779.It Ic ayt 780If 781.Tn TELNET 782is in localchars mode, or 783.Dv LINEMODE 784is enabled, and the status character is typed, a 785.Dv TELNET AYT 786sequence (see 787.Ic send ayt 788preceding) is sent to the 789remote host. The initial value for the \*(LqAre You There\*(Rq 790character is the terminal's status character. 791.It Ic echo 792This is the value (initially \*(Lq^E\*(Rq) which, when in 793\*(Lqline by line\*(Rq mode, toggles between doing local echoing 794of entered characters (for normal processing), and suppressing 795echoing of entered characters (for entering, say, a password). 796.It Ic eof 797If 798.Nm 799is operating in 800.Dv LINEMODE 801or \*(Lqold line by line\*(Rq mode, entering this character 802as the first character on a line will cause this character to be 803sent to the remote system. 804The initial value of the eof character is taken to be the terminal's 805.Ic eof 806character. 807.It Ic erase 808If 809.Nm 810is in 811.Ic localchars 812mode (see 813.Ic toggle 814.Ic localchars 815below), 816.Sy and 817if 818.Nm 819is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 820character is typed, a 821.Dv TELNET EC 822sequence (see 823.Ic send 824.Ic ec 825above) 826is sent to the remote system. 827The initial value for the erase character is taken to be 828the terminal's 829.Ic erase 830character. 831.It Ic escape 832This is the 833.Nm 834escape character (initially \*(Lq^[\*(Rq) which causes entry 835into 836.Nm 837command mode (when connected to a remote system). 838.It Ic flushoutput 839If 840.Nm 841is in 842.Ic localchars 843mode (see 844.Ic toggle 845.Ic localchars 846below) 847and the 848.Ic flushoutput 849character is typed, a 850.Dv TELNET AO 851sequence (see 852.Ic send 853.Ic ao 854above) 855is sent to the remote host. 856The initial value for the flush character is taken to be 857the terminal's 858.Ic flush 859character. 860.It Ic forw1 861.It Ic forw2 862If 863.Nm 864is operating in 865.Dv LINEMODE , 866these are the 867characters that, when typed, cause partial lines to be 868forwarded to the remote system. The initial value for 869the forwarding characters are taken from the terminal's 870eol and eol2 characters. 871.It Ic interrupt 872If 873.Nm 874is in 875.Ic localchars 876mode (see 877.Ic toggle 878.Ic localchars 879below) 880and the 881.Ic interrupt 882character is typed, a 883.Dv TELNET IP 884sequence (see 885.Ic send 886.Ic ip 887above) 888is sent to the remote host. 889The initial value for the interrupt character is taken to be 890the terminal's 891.Ic intr 892character. 893.It Ic kill 894If 895.Nm 896is in 897.Ic localchars 898mode (see 899.Ic toggle 900.Ic localchars 901below), 902.Ic and 903if 904.Nm 905is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 906character is typed, a 907.Dv TELNET EL 908sequence (see 909.Ic send 910.Ic el 911above) 912is sent to the remote system. 913The initial value for the kill character is taken to be 914the terminal's 915.Ic kill 916character. 917.It Ic lnext 918If 919.Nm 920is operating in 921.Dv LINEMODE 922or \*(Lqold line by line\*(Rq mode, then this character is taken to 923be the terminal's 924.Ic lnext 925character. 926The initial value for the lnext character is taken to be 927the terminal's 928.Ic lnext 929character. 930.It Ic quit 931If 932.Nm 933is in 934.Ic localchars 935mode (see 936.Ic toggle 937.Ic localchars 938below) 939and the 940.Ic quit 941character is typed, a 942.Dv TELNET BRK 943sequence (see 944.Ic send 945.Ic brk 946above) 947is sent to the remote host. 948The initial value for the quit character is taken to be 949the terminal's 950.Ic quit 951character. 952.It Ic reprint 953If 954.Nm 955is operating in 956.Dv LINEMODE 957or \*(Lqold line by line\*(Rq mode, then this character is taken to 958be the terminal's 959.Ic reprint 960character. 961The initial value for the reprint character is taken to be 962the terminal's 963.Ic reprint 964character. 965.It Ic rlogin 966This is the rlogin escape character. 967If set, the normal 968.Nm 969escape character is ignored unless it is 970preceded by this character at the beginning of a line. 971This character, at the beginning of a line followed by 972a "." closes the connection; when followed by a ^Z it 973suspends the 974.Nm 975command. The initial state is to 976disable the 977.Nm rlogin 978escape character. 979.It Ic start 980If the 981.Dv TELNET TOGGLE-FLOW-CONTROL 982option has been enabled, 983then this character is taken to 984be the terminal's 985.Ic start 986character. 987The initial value for the start character is taken to be 988the terminal's 989.Ic start 990character. 991.It Ic stop 992If the 993.Dv TELNET TOGGLE-FLOW-CONTROL 994option has been enabled, 995then this character is taken to 996be the terminal's 997.Ic stop 998character. 999The initial value for the stop character is taken to be 1000the terminal's 1001.Ic stop 1002character. 1003.It Ic susp 1004If 1005.Nm 1006is in 1007.Ic localchars 1008mode, or 1009.Dv LINEMODE 1010is enabled, and the 1011.Ic suspend 1012character is typed, a 1013.Dv TELNET SUSP 1014sequence (see 1015.Ic send 1016.Ic susp 1017above) 1018is sent to the remote host. 1019The initial value for the suspend character is taken to be 1020the terminal's 1021.Ic suspend 1022character. 1023.It Ic tracefile 1024This is the file to which the output, caused by 1025.Ic netdata 1026or 1027.Ic option 1028tracing being 1029.Dv TRUE , 1030will be written. If it is set to 1031.Dq Fl , 1032then tracing information will be written to standard output (the default). 1033.It Ic worderase 1034If 1035.Nm 1036is operating in 1037.Dv LINEMODE 1038or \*(Lqold line by line\*(Rq mode, then this character is taken to 1039be the terminal's 1040.Ic worderase 1041character. 1042The initial value for the worderase character is taken to be 1043the terminal's 1044.Ic worderase 1045character. 1046.It Ic ?\& 1047Displays the legal 1048.Ic set 1049.Pq Ic unset 1050commands. 1051.El 1052.It Ic opie Ar sequence challenge 1053The 1054.Ic opie 1055command computes a response to the OPIE challenge. 1056.It Ic slc Ar state 1057The 1058.Ic slc 1059command (Set Local Characters) is used to set 1060or change the state of the special 1061characters when the 1062.Dv TELNET LINEMODE 1063option has 1064been enabled. Special characters are characters that get 1065mapped to 1066.Tn TELNET 1067commands sequences (like 1068.Ic ip 1069or 1070.Ic quit ) 1071or line editing characters (like 1072.Ic erase 1073and 1074.Ic kill ) . 1075By default, the local special characters are exported. 1076.Bl -tag -width Fl 1077.It Ic check 1078Verify the current settings for the current special characters. 1079The remote side is requested to send all the current special 1080character settings, and if there are any discrepancies with 1081the local side, the local side will switch to the remote value. 1082.It Ic export 1083Switch to the local defaults for the special characters. The 1084local default characters are those of the local terminal at 1085the time when 1086.Nm 1087was started. 1088.It Ic import 1089Switch to the remote defaults for the special characters. 1090The remote default characters are those of the remote system 1091at the time when the 1092.Tn TELNET 1093connection was established. 1094.It Ic ?\& 1095Prints out help information for the 1096.Ic slc 1097command. 1098.El 1099.It Ic status 1100Show the current status of 1101.Nm . 1102This includes the peer one is connected to, as well 1103as the current mode. 1104.It Ic toggle Ar arguments ... 1105Toggle (between 1106.Dv TRUE 1107and 1108.Dv FALSE ) 1109various flags that control how 1110.Nm 1111responds to events. 1112These flags may be set explicitly to 1113.Dv TRUE 1114or 1115.Dv FALSE 1116using the 1117.Ic set 1118and 1119.Ic unset 1120commands listed above. 1121More than one argument may be specified. 1122The state of these flags may be interrogated with the 1123.Ic display 1124command. 1125Valid arguments are: 1126.Bl -tag -width Ar 1127.It Ic authdebug 1128Turns on debugging information for the authentication code. 1129.It Ic autoflush 1130If 1131.Ic autoflush 1132and 1133.Ic localchars 1134are both 1135.Dv TRUE , 1136then when the 1137.Ic ao , 1138or 1139.Ic quit 1140characters are recognized (and transformed into 1141.Tn TELNET 1142sequences; see 1143.Ic set 1144above for details), 1145.Nm 1146refuses to display any data on the user's terminal 1147until the remote system acknowledges (via a 1148.Dv TELNET TIMING MARK 1149option) 1150that it has processed those 1151.Tn TELNET 1152sequences. 1153The initial value for this toggle is 1154.Dv TRUE 1155if the terminal user had not 1156done an "stty noflsh", otherwise 1157.Dv FALSE 1158(see 1159.Xr stty 1 ) . 1160.It Ic autodecrypt 1161When the 1162.Dv TELNET ENCRYPT 1163option is negotiated, by 1164default the actual encryption (decryption) of the data 1165stream does not start automatically. The autoencrypt 1166(autodecrypt) command states that encryption of the 1167output (input) stream should be enabled as soon as 1168possible. 1169.It Ic autologin 1170If the remote side supports the 1171.Dv TELNET AUTHENTICATION 1172option 1173.Nm 1174attempts to use it to perform automatic authentication. If the 1175.Dv AUTHENTICATION 1176option is not supported, the user's login 1177name are propagated through the 1178.Dv TELNET ENVIRON 1179option. 1180This command is the same as specifying 1181.Fl a 1182option on the 1183.Ic open 1184command. 1185.It Ic autosynch 1186If 1187.Ic autosynch 1188and 1189.Ic localchars 1190are both 1191.Dv TRUE , 1192then when either the 1193.Ic intr 1194or 1195.Ic quit 1196characters is typed (see 1197.Ic set 1198above for descriptions of the 1199.Ic intr 1200and 1201.Ic quit 1202characters), the resulting 1203.Tn TELNET 1204sequence sent is followed by the 1205.Dv TELNET SYNCH 1206sequence. 1207This procedure 1208.Ic should 1209cause the remote system to begin throwing away all previously 1210typed input until both of the 1211.Tn TELNET 1212sequences have been read and acted upon. 1213The initial value of this toggle is 1214.Dv FALSE . 1215.It Ic binary 1216Enable or disable the 1217.Dv TELNET BINARY 1218option on both input and output. 1219.It Ic inbinary 1220Enable or disable the 1221.Dv TELNET BINARY 1222option on input. 1223.It Ic outbinary 1224Enable or disable the 1225.Dv TELNET BINARY 1226option on output. 1227.It Ic crlf 1228If this is 1229.Dv TRUE , 1230then carriage returns will be sent as 1231.Li <CR><LF> . 1232If this is 1233.Dv FALSE , 1234then carriage returns will be send as 1235.Li <CR><NUL> . 1236The initial value for this toggle is 1237.Dv FALSE . 1238.It Ic crmod 1239Toggle carriage return mode. 1240When this mode is enabled, most carriage return characters received from 1241the remote host will be mapped into a carriage return followed by 1242a line feed. 1243This mode does not affect those characters typed by the user, only 1244those received from the remote host. 1245This mode is not very useful unless the remote host 1246only sends carriage return, but never line feed. 1247The initial value for this toggle is 1248.Dv FALSE . 1249.It Ic debug 1250Toggles socket level debugging (useful only to the 1251.Ic super user ) . 1252The initial value for this toggle is 1253.Dv FALSE . 1254.It Ic encdebug 1255Turns on debugging information for the encryption code. 1256.It Ic localchars 1257If this is 1258.Dv TRUE , 1259then the 1260.Ic flush , 1261.Ic interrupt , 1262.Ic quit , 1263.Ic erase , 1264and 1265.Ic kill 1266characters (see 1267.Ic set 1268above) are recognized locally, and transformed into (hopefully) appropriate 1269.Tn TELNET 1270control sequences 1271(respectively 1272.Ic ao , 1273.Ic ip , 1274.Ic brk , 1275.Ic ec , 1276and 1277.Ic el ; 1278see 1279.Ic send 1280above). 1281The initial value for this toggle is 1282.Dv TRUE 1283in \*(Lqold line by line\*(Rq mode, 1284and 1285.Dv FALSE 1286in \*(Lqcharacter at a time\*(Rq mode. 1287When the 1288.Dv LINEMODE 1289option is enabled, the value of 1290.Ic localchars 1291is ignored, and assumed to always be 1292.Dv TRUE . 1293If 1294.Dv LINEMODE 1295has ever been enabled, then 1296.Ic quit 1297is sent as 1298.Ic abort , 1299and 1300.Ic eof 1301and 1302.Ic suspend 1303are sent as 1304.Ic eof 1305and 1306.Ic susp 1307(see 1308.Ic send 1309above). 1310.It Ic netdata 1311Toggles the display of all network data (in hexadecimal format). 1312The initial value for this toggle is 1313.Dv FALSE . 1314.It Ic options 1315Toggles the display of some internal 1316.Nm 1317protocol processing (having to do with 1318.Tn TELNET 1319options). 1320The initial value for this toggle is 1321.Dv FALSE . 1322.It Ic prettydump 1323When the 1324.Ic netdata 1325toggle is enabled, if 1326.Ic prettydump 1327is enabled the output from the 1328.Ic netdata 1329command will be formatted in a more user readable format. 1330Spaces are put between each character in the output, and the 1331beginning of any 1332.Nm 1333escape sequence is preceded by a '*' to aid in locating them. 1334.It Ic skiprc 1335When the skiprc toggle is 1336.Dv TRUE , 1337.Nm 1338skips the reading of the 1339.Pa \&.telnetrc 1340file in the users home 1341directory when connections are opened. The initial 1342value for this toggle is 1343.Dv FALSE . 1344.It Ic termdata 1345Toggles the display of all terminal data (in hexadecimal format). 1346The initial value for this toggle is 1347.Dv FALSE . 1348.It Ic verbose_encrypt 1349When the 1350.Ic verbose_encrypt 1351toggle is 1352.Dv TRUE , 1353.Nm 1354prints out a message each time encryption is enabled or 1355disabled. The initial value for this toggle is 1356.Dv FALSE . 1357.It Ic ?\& 1358Displays the legal 1359.Ic toggle 1360commands. 1361.El 1362.It Ic z 1363Suspend 1364.Nm . 1365This command only works when the user is using the 1366.Xr csh 1 . 1367.It Ic \&! Op Ar command 1368Execute a single command in a subshell on the local 1369system. If 1370.Ar command 1371is omitted, then an interactive 1372subshell is invoked. 1373.It Ic ?\& Op Ar command 1374Get help. With no arguments, 1375.Nm 1376prints a help summary. 1377If 1378.Ar command 1379is specified, 1380.Nm 1381will print the help information for just that command. 1382.El 1383.Sh ENVIRONMENT 1384The 1385.Nm 1386utility uses at least the 1387.Ev HOME , 1388.Ev SHELL , 1389.Ev DISPLAY , 1390and 1391.Ev TERM 1392environment variables. 1393Other environment variables may be propagated 1394to the other side via the 1395.Dv TELNET ENVIRON 1396option. 1397.Sh FILES 1398.Bl -tag -width ~/.telnetrc -compact 1399.It Pa ~/.telnetrc 1400user customized telnet startup values 1401.El 1402.Sh SEE ALSO 1403.Xr rlogin 1 , 1404.Xr rsh 1 , 1405.Xr hosts 5 , 1406.Xr nologin 5 , 1407.Xr telnetd 8 1408.Sh HISTORY 1409The 1410.Nm 1411command appeared in 1412.Bx 4.2 . 1413.Pp 1414IPv6 support was added by WIDE/KAME project. 1415.Sh NOTES 1416On some remote systems, echo has to be turned off manually when in 1417\*(Lqold line by line\*(Rq mode. 1418.Pp 1419In \*(Lqold line by line\*(Rq mode or 1420.Dv LINEMODE 1421the terminal's 1422.Ic eof 1423character is only recognized (and sent to the remote system) 1424when it is the first character on a line. 1425