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