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 8.5 (Berkeley) 3/1/94 33.\" $FreeBSD: src/usr.bin/telnet/telnet.1,v 1.15.2.12 2002/12/29 16:35:40 schweikh Exp $ 34.\" $DragonFly: src/usr.bin/telnet/telnet.1,v 1.3 2006/02/17 19:39:11 swildner Exp $ 35.\" 36.Dd January 27, 2000 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 468EFKLNacdfrux 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. 102.It Fl L 103Specifies an 8-bit data path on output. This causes the 104.Dv BINARY 105option to be negotiated on output. 106.It Fl N 107Prevents IP address to name lookup when destination host is given 108as an IP address. 109.It Fl S Ar tos 110Sets the IP type-of-service (TOS) option for the telnet 111connection to the value 112.Ar tos , 113which can be a numeric TOS value 114or, on systems that support it, a symbolic 115TOS name found in the 116.Pa /etc/iptos 117file. 118.It Fl X Ar atype 119Disables the 120.Ar atype 121type of authentication. 122.It Fl a 123Attempt automatic login. 124Currently, this sends the user name via the 125.Ev USER 126variable 127of the 128.Ev ENVIRON 129option if supported by the remote system. 130The name used is that of the current user as returned by 131.Xr getlogin 2 132if it agrees with the current user ID, 133otherwise it is the name associated with the user ID. 134.It Fl c 135Disables the reading of the user's 136.Pa \&.telnetrc 137file. (See the 138.Ic toggle skiprc 139command on this man page.) 140.It Fl d 141Sets the initial value of the 142.Ic debug 143toggle to 144.Dv TRUE . 145.It Fl e Ar escapechar 146Sets the initial 147.Nm 148escape character to 149.Ar escapechar . 150If 151.Ar escapechar 152is omitted, then 153there will be no escape character. 154.It Fl f 155If Kerberos V5 authentication is being used, the 156.Fl f 157option allows the local credentials to be forwarded to the remote system. 158.It Fl k Ar realm 159If Kerberos authentication is being used, the 160.Fl k 161option requests that 162.Nm 163obtain tickets for the remote host in 164realm 165.Ar realm 166instead of the remote host's realm, as determined by 167.Xr krb_realmofhost 3 . 168.It Fl l Ar user 169When connecting to the remote system, if the remote system 170understands the 171.Ev ENVIRON 172option, then 173.Ar user 174will be sent to the remote system as the value for the variable 175.Ev USER . 176This option implies the 177.Fl a 178option. 179This option may also be used with the 180.Ic open 181command. 182.It Fl n Ar tracefile 183Opens 184.Ar tracefile 185for recording trace information. 186See the 187.Ic set tracefile 188command below. 189.It Fl r 190Specifies a user interface similar to 191.Xr rlogin 1 . 192In this 193mode, the escape character is set to the tilde (~) character, 194unless modified by the 195.Fl e 196option. 197.It Fl s Ar src_addr 198Set the source IP address for the 199.Nm 200connection to 201.Ar src_addr , 202which can be an IP address or a host name. 203.It Fl u 204Forces 205.Nm 206to use 207.Dv AF_UNIX 208addresses only (e.g., 209.Ux 210domain sockets, accessed with a file path). 211.It Fl x 212Turns on encryption of the data stream if possible. 213.It Ar host 214Indicates the official name, an alias, or the Internet address 215of a remote host. 216If 217.Ar host 218starts with a 219.Ql / , 220.Nm 221establishes a connection to the corresponding named socket. 222.It Ar port 223Indicates a port number (address of an application). If a number is 224not specified, the default 225.Nm 226port is used. 227.El 228.Pp 229When in rlogin mode, a line of the form ~. disconnects from the 230remote host; ~ is the 231.Nm 232escape character. 233Similarly, the line ~^Z suspends the 234.Nm 235session. 236The line ~^] escapes to the normal 237.Nm 238escape prompt. 239.Pp 240Once a connection has been opened, 241.Nm 242will attempt to enable the 243.Dv TELNET LINEMODE 244option. 245If this fails, then 246.Nm 247will revert to one of two input modes: 248either \*(Lqcharacter at a time\*(Rq 249or \*(Lqold line by line\*(Rq 250depending on what the remote system supports. 251.Pp 252When 253.Dv LINEMODE 254is enabled, character processing is done on the 255local system, under the control of the remote system. When input 256editing or character echoing is to be disabled, the remote system 257will relay that information. The remote system will also relay 258changes to any special characters that happen on the remote 259system, so that they can take effect on the local system. 260.Pp 261In \*(Lqcharacter at a time\*(Rq mode, most 262text typed is immediately sent to the remote host for processing. 263.Pp 264In \*(Lqold line by line\*(Rq mode, all text is echoed locally, 265and (normally) only completed lines are sent to the remote host. 266The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used 267to turn off and on the local echo 268(this would mostly be used to enter passwords 269without the password being echoed). 270.Pp 271If the 272.Dv LINEMODE 273option is enabled, or if the 274.Ic localchars 275toggle is 276.Dv TRUE 277(the default for \*(Lqold line by line\*(Rq; see below), 278the user's 279.Ic quit , 280.Ic intr , 281and 282.Ic flush 283characters are trapped locally, and sent as 284.Tn TELNET 285protocol sequences to the remote side. 286If 287.Dv LINEMODE 288has ever been enabled, then the user's 289.Ic susp 290and 291.Ic eof 292are also sent as 293.Tn TELNET 294protocol sequences, 295and 296.Ic quit 297is sent as a 298.Dv TELNET ABORT 299instead of 300.Dv BREAK . 301There are options (see 302.Ic toggle 303.Ic autoflush 304and 305.Ic toggle 306.Ic autosynch 307below) 308which cause this action to flush subsequent output to the terminal 309(until the remote host acknowledges the 310.Tn TELNET 311sequence) and flush previous terminal input 312(in the case of 313.Ic quit 314and 315.Ic intr ) . 316.Pp 317While connected to a remote host, 318.Nm 319command mode may be entered by typing the 320.Nm 321\*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq). 322When in command mode, the normal terminal editing conventions are available. 323.Pp 324The following 325.Nm 326commands are available. 327Only enough of each command to uniquely identify it need be typed 328(this is also true for arguments to the 329.Ic mode , 330.Ic set , 331.Ic toggle , 332.Ic unset , 333.Ic slc , 334.Ic environ , 335and 336.Ic display 337commands). 338.Pp 339.Bl -tag -width "mode type" 340.It Ic auth Ar argument ... 341The auth command manipulates the information sent through the 342.Dv TELNET AUTHENTICATE 343option. Valid arguments for the 344.Ic auth 345command are: 346.Bl -tag -width "disable type" 347.It Ic disable Ar type 348Disables the specified type of authentication. To 349obtain a list of available types, use the 350.Ic auth disable ?\& 351command. 352.It Ic enable Ar type 353Enables the specified type of authentication. To 354obtain a list of available types, use the 355.Ic auth enable ?\& 356command. 357.It Ic status 358Lists the current status of the various types of 359authentication. 360.El 361.It Ic close 362Close a 363.Tn TELNET 364session and return to command mode. 365.It Ic display Ar argument ... 366Displays all, or some, of the 367.Ic set 368and 369.Ic toggle 370values (see below). 371.It Ic encrypt Ar argument ... 372The encrypt command manipulates the information sent through the 373.Dv TELNET ENCRYPT 374option. 375.Pp 376Valid arguments for the 377.Ic encrypt 378command are: 379.Bl -tag -width Ar 380.It Ic disable Ar type Xo 381.Op Cm input | output 382.Xc 383Disables the specified type of encryption. If you 384omit the input and output, both input and output 385are disabled. To obtain a list of available 386types, use the 387.Ic encrypt disable ?\& 388command. 389.It Ic enable Ar type Xo 390.Op Cm input | output 391.Xc 392Enables the specified type of encryption. If you 393omit input and output, both input and output are 394enabled. To obtain a list of available types, use the 395.Ic encrypt enable ?\& 396command. 397.It Ic input 398This is the same as the 399.Ic encrypt start input 400command. 401.It Ic -input 402This is the same as the 403.Ic encrypt stop input 404command. 405.It Ic output 406This is the same as the 407.Ic encrypt start output 408command. 409.It Ic -output 410This is the same as the 411.Ic encrypt stop output 412command. 413.It Ic start Op Cm input | output 414Attempts to start encryption. If you omit 415.Ic input 416and 417.Ic output , 418both input and output are enabled. To 419obtain a list of available types, use the 420.Ic encrypt enable ?\& 421command. 422.It Ic status 423Lists the current status of encryption. 424.It Ic stop Op Cm input | output 425Stops encryption. If you omit input and output, 426encryption is on both input and output. 427.It Ic type Ar type 428Sets the default type of encryption to be used 429with later 430.Ic encrypt start 431or 432.Ic encrypt stop 433commands. 434.El 435.It Ic environ Ar arguments ... 436The 437.Ic environ 438command is used to manipulate the 439variables that may be sent through the 440.Dv TELNET ENVIRON 441option. 442The initial set of variables is taken from the users 443environment, with only the 444.Ev DISPLAY 445and 446.Ev PRINTER 447variables being exported by default. 448The 449.Ev USER 450variable is also exported if the 451.Fl a 452or 453.Fl l 454options are used. 455.Pp 456Valid arguments for the 457.Ic environ 458command are: 459.Bl -tag -width Fl 460.It Ic define Ar variable value 461Define the variable 462.Ar variable 463to have a value of 464.Ar value . 465Any variables defined by this command are automatically exported. 466The 467.Ar value 468may be enclosed in single or double quotes so 469that tabs and spaces may be included. 470.It Ic undefine Ar variable 471Remove 472.Ar variable 473from the list of environment variables. 474.It Ic export Ar variable 475Mark the variable 476.Ar variable 477to be exported to the remote side. 478.It Ic unexport Ar variable 479Mark the variable 480.Ar variable 481to not be exported unless 482explicitly asked for by the remote side. 483.It Ic list 484List the current set of environment variables. 485Those marked with a 486.Cm * 487will be sent automatically, 488other variables will only be sent if explicitly requested. 489.It Ic ?\& 490Prints out help information for the 491.Ic environ 492command. 493.El 494.It Ic logout 495Sends the 496.Dv TELNET LOGOUT 497option to the remote side. 498This command is similar to a 499.Ic close 500command; however, if the remote side does not support the 501.Dv LOGOUT 502option, nothing happens. 503If, however, the remote side does support the 504.Dv LOGOUT 505option, this command should cause the remote side to close the 506.Tn TELNET 507connection. 508If the remote side also supports the concept of 509suspending a user's session for later reattachment, 510the logout argument indicates that you 511should terminate the session immediately. 512.It Ic mode Ar type 513.Ar Type 514is one of several options, depending on the state of the 515.Tn TELNET 516session. 517The remote host is asked for permission to go into the requested mode. 518If the remote host is capable of entering that mode, the requested 519mode will be entered. 520.Bl -tag -width Ar 521.It Ic character 522Disable the 523.Dv TELNET LINEMODE 524option, or, if the remote side does not understand the 525.Dv LINEMODE 526option, then enter \*(Lqcharacter at a time\*(Rq mode. 527.It Ic line 528Enable the 529.Dv TELNET LINEMODE 530option, or, if the remote side does not understand the 531.Dv LINEMODE 532option, then attempt to enter \*(Lqold-line-by-line\*(Rq mode. 533.It Ic isig Pq Ic \-isig 534Attempt to enable (disable) the 535.Dv TRAPSIG 536mode of the 537.Dv LINEMODE 538option. 539This requires that the 540.Dv LINEMODE 541option be enabled. 542.It Ic edit Pq Ic \-edit 543Attempt to enable (disable) the 544.Dv EDIT 545mode of the 546.Dv LINEMODE 547option. 548This requires that the 549.Dv LINEMODE 550option be enabled. 551.It Ic softtabs Pq Ic \-softtabs 552Attempt to enable (disable) the 553.Dv SOFT_TAB 554mode of the 555.Dv LINEMODE 556option. 557This requires that the 558.Dv LINEMODE 559option be enabled. 560.It Ic litecho Pq Ic \-litecho 561Attempt to enable (disable) the 562.Dv LIT_ECHO 563mode of the 564.Dv LINEMODE 565option. 566This requires that the 567.Dv LINEMODE 568option be enabled. 569.It Ic ?\& 570Prints out help information for the 571.Ic mode 572command. 573.El 574.It Xo 575.Ic open Ar host 576.Op Fl l Ar user 577.Op Oo Fl Oc Ns Ar port 578.Xc 579Open a connection to the named host. 580If no port number 581is specified, 582.Nm 583will attempt to contact a 584.Tn TELNET 585server at the default port. 586The host specification may be either a host name (see 587.Xr hosts 5 ) , 588an Internet address specified in the \*(Lqdot notation\*(Rq (see 589.Xr inet 3 ) , 590or IPv6 host name or IPv6 coloned-hexadecimal address. 591The 592.Fl l 593option may be used to specify the user name 594to be passed to the remote system via the 595.Ev ENVIRON 596option. 597When connecting to a non-standard port, 598.Nm 599omits any automatic initiation of 600.Tn TELNET 601options. When the port number is preceded by a minus sign, 602the initial option negotiation is done. 603After establishing a connection, the file 604.Pa \&.telnetrc 605in the 606users home directory is opened. Lines beginning with a # are 607comment lines. Blank lines are ignored. Lines that begin 608without white space are the start of a machine entry. The 609first thing on the line is the name of the machine that is 610being connected to. The rest of the line, and successive 611lines that begin with white space are assumed to be 612.Nm 613commands and are processed as if they had been typed 614in manually to the 615.Nm 616command prompt. 617.It Ic quit 618Close any open 619.Tn TELNET 620session and exit 621.Nm . 622An end of file (in command mode) will also close a session and exit. 623.It Ic send Ar arguments 624Sends one or more special character sequences to the remote host. 625The following are the arguments which may be specified 626(more than one argument may be specified at a time): 627.Pp 628.Bl -tag -width escape 629.It Ic abort 630Sends the 631.Dv TELNET ABORT 632(Abort 633processes) 634sequence. 635.It Ic ao 636Sends the 637.Dv TELNET AO 638(Abort Output) sequence, which should cause the remote system to flush 639all output 640.Em from 641the remote system 642.Em to 643the user's terminal. 644.It Ic ayt 645Sends the 646.Dv TELNET AYT 647(Are You There) 648sequence, to which the remote system may or may not choose to respond. 649.It Ic brk 650Sends the 651.Dv TELNET BRK 652(Break) sequence, which may have significance to the remote 653system. 654.It Ic ec 655Sends the 656.Dv TELNET EC 657(Erase Character) 658sequence, which should cause the remote system to erase the last character 659entered. 660.It Ic el 661Sends the 662.Dv TELNET EL 663(Erase Line) 664sequence, which should cause the remote system to erase the line currently 665being entered. 666.It Ic eof 667Sends the 668.Dv TELNET EOF 669(End Of File) 670sequence. 671.It Ic eor 672Sends the 673.Dv TELNET EOR 674(End of Record) 675sequence. 676.It Ic escape 677Sends the current 678.Nm 679escape character (initially \*(Lq^\*(Rq). 680.It Ic ga 681Sends the 682.Dv TELNET GA 683(Go Ahead) 684sequence, which likely has no significance to the remote system. 685.It Ic getstatus 686If the remote side supports the 687.Dv TELNET STATUS 688command, 689.Ic getstatus 690will send the subnegotiation to request that the server send 691its current option status. 692.It Ic ip 693Sends the 694.Dv TELNET IP 695(Interrupt Process) sequence, which should cause the remote 696system to abort the currently running process. 697.It Ic nop 698Sends the 699.Dv TELNET NOP 700(No OPeration) 701sequence. 702.It Ic susp 703Sends the 704.Dv TELNET SUSP 705(SUSPend process) 706sequence. 707.It Ic synch 708Sends the 709.Dv TELNET SYNCH 710sequence. 711This sequence causes the remote system to discard all previously typed 712(but not yet read) input. 713This sequence is sent as 714.Tn TCP 715urgent 716data (and may not work if the remote system is a 717.Bx 4.2 718system -- if 719it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal). 720.It Ic do Ar cmd 721.It Ic dont Ar cmd 722.It Ic will Ar cmd 723.It Ic wont Ar cmd 724Sends the 725.Dv TELNET DO 726.Ar cmd 727sequence. 728.Ar Cmd 729can be either a decimal number between 0 and 255, 730or a symbolic name for a specific 731.Dv TELNET 732command. 733.Ar Cmd 734can also be either 735.Ic help 736or 737.Ic ?\& 738to print out help information, including 739a list of known symbolic names. 740.It Ic ?\& 741Prints out help information for the 742.Ic send 743command. 744.El 745.It Ic set Ar argument value 746.It Ic unset Ar argument value 747The 748.Ic set 749command will set any one of a number of 750.Nm 751variables to a specific value or to 752.Dv TRUE . 753The special value 754.Ic off 755turns off the function associated with 756the variable, this is equivalent to using the 757.Ic unset 758command. 759The 760.Ic unset 761command will disable or set to 762.Dv FALSE 763any of the specified functions. 764The values of variables may be interrogated with the 765.Ic display 766command. 767The variables which may be set or unset, but not toggled, are 768listed here. In addition, any of the variables for the 769.Ic toggle 770command may be explicitly set or unset using 771the 772.Ic set 773and 774.Ic unset 775commands. 776.Bl -tag -width escape 777.It Ic ayt 778If 779.Tn TELNET 780is in localchars mode, or 781.Dv LINEMODE 782is enabled, and the status character is typed, a 783.Dv TELNET AYT 784sequence (see 785.Ic send ayt 786preceding) is sent to the 787remote host. The initial value for the \*(LqAre You There\*(Rq 788character is the terminal's status character. 789.It Ic echo 790This is the value (initially \*(Lq^E\*(Rq) which, when in 791\*(Lqline by line\*(Rq mode, toggles between doing local echoing 792of entered characters (for normal processing), and suppressing 793echoing of entered characters (for entering, say, a password). 794.It Ic eof 795If 796.Nm 797is operating in 798.Dv LINEMODE 799or \*(Lqold line by line\*(Rq mode, entering this character 800as the first character on a line will cause this character to be 801sent to the remote system. 802The initial value of the eof character is taken to be the terminal's 803.Ic eof 804character. 805.It Ic erase 806If 807.Nm 808is in 809.Ic localchars 810mode (see 811.Ic toggle 812.Ic localchars 813below), 814.Sy and 815if 816.Nm 817is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 818character is typed, a 819.Dv TELNET EC 820sequence (see 821.Ic send 822.Ic ec 823above) 824is sent to the remote system. 825The initial value for the erase character is taken to be 826the terminal's 827.Ic erase 828character. 829.It Ic escape 830This is the 831.Nm 832escape character (initially \*(Lq^[\*(Rq) which causes entry 833into 834.Nm 835command mode (when connected to a remote system). 836.It Ic flushoutput 837If 838.Nm 839is in 840.Ic localchars 841mode (see 842.Ic toggle 843.Ic localchars 844below) 845and the 846.Ic flushoutput 847character is typed, a 848.Dv TELNET AO 849sequence (see 850.Ic send 851.Ic ao 852above) 853is sent to the remote host. 854The initial value for the flush character is taken to be 855the terminal's 856.Ic flush 857character. 858.It Ic forw1 859.It Ic forw2 860If 861.Nm 862is operating in 863.Dv LINEMODE , 864these are the 865characters that, when typed, cause partial lines to be 866forwarded to the remote system. The initial value for 867the forwarding characters are taken from the terminal's 868eol and eol2 characters. 869.It Ic interrupt 870If 871.Nm 872is in 873.Ic localchars 874mode (see 875.Ic toggle 876.Ic localchars 877below) 878and the 879.Ic interrupt 880character is typed, a 881.Dv TELNET IP 882sequence (see 883.Ic send 884.Ic ip 885above) 886is sent to the remote host. 887The initial value for the interrupt character is taken to be 888the terminal's 889.Ic intr 890character. 891.It Ic kill 892If 893.Nm 894is in 895.Ic localchars 896mode (see 897.Ic toggle 898.Ic localchars 899below), 900.Ic and 901if 902.Nm 903is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 904character is typed, a 905.Dv TELNET EL 906sequence (see 907.Ic send 908.Ic el 909above) 910is sent to the remote system. 911The initial value for the kill character is taken to be 912the terminal's 913.Ic kill 914character. 915.It Ic lnext 916If 917.Nm 918is operating in 919.Dv LINEMODE 920or \*(Lqold line by line\*(Rq mode, then this character is taken to 921be the terminal's 922.Ic lnext 923character. 924The initial value for the lnext character is taken to be 925the terminal's 926.Ic lnext 927character. 928.It Ic quit 929If 930.Nm 931is in 932.Ic localchars 933mode (see 934.Ic toggle 935.Ic localchars 936below) 937and the 938.Ic quit 939character is typed, a 940.Dv TELNET BRK 941sequence (see 942.Ic send 943.Ic brk 944above) 945is sent to the remote host. 946The initial value for the quit character is taken to be 947the terminal's 948.Ic quit 949character. 950.It Ic reprint 951If 952.Nm 953is operating in 954.Dv LINEMODE 955or \*(Lqold line by line\*(Rq mode, then this character is taken to 956be the terminal's 957.Ic reprint 958character. 959The initial value for the reprint character is taken to be 960the terminal's 961.Ic reprint 962character. 963.It Ic rlogin 964This is the rlogin escape character. 965If set, the normal 966.Nm 967escape character is ignored unless it is 968preceded by this character at the beginning of a line. 969This character, at the beginning of a line followed by 970a "." closes the connection; when followed by a ^Z it 971suspends the 972.Nm 973command. The initial state is to 974disable the 975.Nm rlogin 976escape character. 977.It Ic start 978If the 979.Dv TELNET TOGGLE-FLOW-CONTROL 980option has been enabled, 981then this character is taken to 982be the terminal's 983.Ic start 984character. 985The initial value for the start character is taken to be 986the terminal's 987.Ic start 988character. 989.It Ic stop 990If the 991.Dv TELNET TOGGLE-FLOW-CONTROL 992option has been enabled, 993then this character is taken to 994be the terminal's 995.Ic stop 996character. 997The initial value for the stop character is taken to be 998the terminal's 999.Ic stop 1000character. 1001.It Ic susp 1002If 1003.Nm 1004is in 1005.Ic localchars 1006mode, or 1007.Dv LINEMODE 1008is enabled, and the 1009.Ic suspend 1010character is typed, a 1011.Dv TELNET SUSP 1012sequence (see 1013.Ic send 1014.Ic susp 1015above) 1016is sent to the remote host. 1017The initial value for the suspend character is taken to be 1018the terminal's 1019.Ic suspend 1020character. 1021.It Ic tracefile 1022This is the file to which the output, caused by 1023.Ic netdata 1024or 1025.Ic option 1026tracing being 1027.Dv TRUE , 1028will be written. If it is set to 1029.Dq Fl , 1030then tracing information will be written to standard output (the default). 1031.It Ic worderase 1032If 1033.Nm 1034is operating in 1035.Dv LINEMODE 1036or \*(Lqold line by line\*(Rq mode, then this character is taken to 1037be the terminal's 1038.Ic worderase 1039character. 1040The initial value for the worderase character is taken to be 1041the terminal's 1042.Ic worderase 1043character. 1044.It Ic ?\& 1045Displays the legal 1046.Ic set 1047.Pq Ic unset 1048commands. 1049.El 1050.It Ic skey Ar sequence challenge 1051The 1052.Ic skey 1053command computes a response to the S/Key challenge. 1054.It Ic slc Ar state 1055The 1056.Ic slc 1057command (Set Local Characters) is used to set 1058or change the state of the special 1059characters when the 1060.Dv TELNET LINEMODE 1061option has 1062been enabled. Special characters are characters that get 1063mapped to 1064.Tn TELNET 1065commands sequences (like 1066.Ic ip 1067or 1068.Ic quit ) 1069or line editing characters (like 1070.Ic erase 1071and 1072.Ic kill ) . 1073By default, the local special characters are exported. 1074.Bl -tag -width Fl 1075.It Ic check 1076Verify the current settings for the current special characters. 1077The remote side is requested to send all the current special 1078character settings, and if there are any discrepancies with 1079the local side, the local side will switch to the remote value. 1080.It Ic export 1081Switch to the local defaults for the special characters. The 1082local default characters are those of the local terminal at 1083the time when 1084.Nm 1085was started. 1086.It Ic import 1087Switch to the remote defaults for the special characters. 1088The remote default characters are those of the remote system 1089at the time when the 1090.Tn TELNET 1091connection was established. 1092.It Ic ?\& 1093Prints out help information for the 1094.Ic slc 1095command. 1096.El 1097.It Ic status 1098Show the current status of 1099.Nm . 1100This includes the peer one is connected to, as well 1101as the current mode. 1102.It Ic toggle Ar arguments ... 1103Toggle (between 1104.Dv TRUE 1105and 1106.Dv FALSE ) 1107various flags that control how 1108.Nm 1109responds to events. 1110These flags may be set explicitly to 1111.Dv TRUE 1112or 1113.Dv FALSE 1114using the 1115.Ic set 1116and 1117.Ic unset 1118commands listed above. 1119More than one argument may be specified. 1120The state of these flags may be interrogated with the 1121.Ic display 1122command. 1123Valid arguments are: 1124.Bl -tag -width Ar 1125.It Ic authdebug 1126Turns on debugging information for the authentication code. 1127.It Ic autoflush 1128If 1129.Ic autoflush 1130and 1131.Ic localchars 1132are both 1133.Dv TRUE , 1134then when the 1135.Ic ao , 1136or 1137.Ic quit 1138characters are recognized (and transformed into 1139.Tn TELNET 1140sequences; see 1141.Ic set 1142above for details), 1143.Nm 1144refuses to display any data on the user's terminal 1145until the remote system acknowledges (via a 1146.Dv TELNET TIMING MARK 1147option) 1148that it has processed those 1149.Tn TELNET 1150sequences. 1151The initial value for this toggle is 1152.Dv TRUE 1153if the terminal user had not 1154done an "stty noflsh", otherwise 1155.Dv FALSE 1156(see 1157.Xr stty 1 ) . 1158.It Ic autodecrypt 1159When the 1160.Dv TELNET ENCRYPT 1161option is negotiated, by 1162default the actual encryption (decryption) of the data 1163stream does not start automatically. The autoencrypt 1164(autodecrypt) command states that encryption of the 1165output (input) stream should be enabled as soon as 1166possible. 1167.It Ic autologin 1168If the remote side supports the 1169.Dv TELNET AUTHENTICATION 1170option 1171.Nm 1172attempts to use it to perform automatic authentication. If the 1173.Dv AUTHENTICATION 1174option is not supported, the user's login 1175name are propagated through the 1176.Dv TELNET ENVIRON 1177option. 1178This command is the same as specifying 1179.Fl a 1180option on the 1181.Ic open 1182command. 1183.It Ic autosynch 1184If 1185.Ic autosynch 1186and 1187.Ic localchars 1188are both 1189.Dv TRUE , 1190then when either the 1191.Ic intr 1192or 1193.Ic quit 1194characters is typed (see 1195.Ic set 1196above for descriptions of the 1197.Ic intr 1198and 1199.Ic quit 1200characters), the resulting 1201.Tn TELNET 1202sequence sent is followed by the 1203.Dv TELNET SYNCH 1204sequence. 1205This procedure 1206.Ic should 1207cause the remote system to begin throwing away all previously 1208typed input until both of the 1209.Tn TELNET 1210sequences have been read and acted upon. 1211The initial value of this toggle is 1212.Dv FALSE . 1213.It Ic binary 1214Enable or disable the 1215.Dv TELNET BINARY 1216option on both input and output. 1217.It Ic inbinary 1218Enable or disable the 1219.Dv TELNET BINARY 1220option on input. 1221.It Ic outbinary 1222Enable or disable the 1223.Dv TELNET BINARY 1224option on output. 1225.It Ic crlf 1226If this is 1227.Dv TRUE , 1228then carriage returns will be sent as 1229.Li <CR><LF> . 1230If this is 1231.Dv FALSE , 1232then carriage returns will be send as 1233.Li <CR><NUL> . 1234The initial value for this toggle is 1235.Dv FALSE . 1236.It Ic crmod 1237Toggle carriage return mode. 1238When this mode is enabled, most carriage return characters received from 1239the remote host will be mapped into a carriage return followed by 1240a line feed. 1241This mode does not affect those characters typed by the user, only 1242those received from the remote host. 1243This mode is not very useful unless the remote host 1244only sends carriage return, but never line feed. 1245The initial value for this toggle is 1246.Dv FALSE . 1247.It Ic debug 1248Toggles socket level debugging (useful only to the 1249.Ic super user ) . 1250The initial value for this toggle is 1251.Dv FALSE . 1252.It Ic encdebug 1253Turns on debugging information for the encryption code. 1254.It Ic localchars 1255If this is 1256.Dv TRUE , 1257then the 1258.Ic flush , 1259.Ic interrupt , 1260.Ic quit , 1261.Ic erase , 1262and 1263.Ic kill 1264characters (see 1265.Ic set 1266above) are recognized locally, and transformed into (hopefully) appropriate 1267.Tn TELNET 1268control sequences 1269(respectively 1270.Ic ao , 1271.Ic ip , 1272.Ic brk , 1273.Ic ec , 1274and 1275.Ic el ; 1276see 1277.Ic send 1278above). 1279The initial value for this toggle is 1280.Dv TRUE 1281in \*(Lqold line by line\*(Rq mode, 1282and 1283.Dv FALSE 1284in \*(Lqcharacter at a time\*(Rq mode. 1285When the 1286.Dv LINEMODE 1287option is enabled, the value of 1288.Ic localchars 1289is ignored, and assumed to always be 1290.Dv TRUE . 1291If 1292.Dv LINEMODE 1293has ever been enabled, then 1294.Ic quit 1295is sent as 1296.Ic abort , 1297and 1298.Ic eof 1299and 1300.Ic suspend 1301are sent as 1302.Ic eof 1303and 1304.Ic susp 1305(see 1306.Ic send 1307above). 1308.It Ic netdata 1309Toggles the display of all network data (in hexadecimal format). 1310The initial value for this toggle is 1311.Dv FALSE . 1312.It Ic options 1313Toggles the display of some internal 1314.Nm 1315protocol processing (having to do with 1316.Tn TELNET 1317options). 1318The initial value for this toggle is 1319.Dv FALSE . 1320.It Ic prettydump 1321When the 1322.Ic netdata 1323toggle is enabled, if 1324.Ic prettydump 1325is enabled the output from the 1326.Ic netdata 1327command will be formatted in a more user readable format. 1328Spaces are put between each character in the output, and the 1329beginning of any 1330.Nm 1331escape sequence is preceded by a '*' to aid in locating them. 1332.It Ic skiprc 1333When the skiprc toggle is 1334.Dv TRUE , 1335.Nm 1336skips the reading of the 1337.Pa \&.telnetrc 1338file in the users home 1339directory when connections are opened. The initial 1340value for this toggle is 1341.Dv FALSE . 1342.It Ic termdata 1343Toggles the display of all terminal data (in hexadecimal format). 1344The initial value for this toggle is 1345.Dv FALSE . 1346.It Ic verbose_encrypt 1347When the 1348.Ic verbose_encrypt 1349toggle is 1350.Dv TRUE , 1351.Nm 1352prints out a message each time encryption is enabled or 1353disabled. The initial value for this toggle is 1354.Dv FALSE . 1355.It Ic ?\& 1356Displays the legal 1357.Ic toggle 1358commands. 1359.El 1360.It Ic z 1361Suspend 1362.Nm . 1363This command only works when the user is using the 1364.Xr csh 1 . 1365.It Ic \&! Op Ar command 1366Execute a single command in a subshell on the local 1367system. If 1368.Ar command 1369is omitted, then an interactive 1370subshell is invoked. 1371.It Ic ?\& Op Ar command 1372Get help. With no arguments, 1373.Nm 1374prints a help summary. 1375If 1376.Ar command 1377is specified, 1378.Nm 1379will print the help information for just that command. 1380.El 1381.Sh ENVIRONMENT 1382The 1383.Nm 1384utility uses at least the 1385.Ev HOME , 1386.Ev SHELL , 1387.Ev DISPLAY , 1388and 1389.Ev TERM 1390environment variables. 1391Other environment variables may be propagated 1392to the other side via the 1393.Dv TELNET ENVIRON 1394option. 1395.Sh FILES 1396.Bl -tag -width ~/.telnetrc -compact 1397.It Pa ~/.telnetrc 1398user customized telnet startup values 1399.El 1400.Sh SEE ALSO 1401.Xr rlogin 1 , 1402.Xr rsh 1 , 1403.Xr hosts 5 , 1404.Xr nologin 5 , 1405.Xr telnetd 8 1406.Sh HISTORY 1407The 1408.Nm 1409command appeared in 1410.Bx 4.2 . 1411.Pp 1412IPv6 support was added by WIDE/KAME project. 1413.Sh NOTES 1414On some remote systems, echo has to be turned off manually when in 1415\*(Lqold line by line\*(Rq mode. 1416.Pp 1417In \*(Lqold line by line\*(Rq mode or 1418.Dv LINEMODE 1419the terminal's 1420.Ic eof 1421character is only recognized (and sent to the remote system) 1422when it is the first character on a line. 1423