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