1.\" Copyright (c) 1983, 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)telnet.1 8.6 (Berkeley) 6/1/94 33.\" $FreeBSD$ 34.\" 35.Dd September 18, 2006 36.Dt TELNET 1 37.Os 38.Sh NAME 39.Nm telnet 40.Nd user interface to the 41.Tn TELNET 42protocol 43.Sh SYNOPSIS 44.Nm 45.Op Fl 468EFKLNacdfruxy 46.Op Fl S Ar tos 47.Op Fl X Ar authtype 48.Op Fl e Ar escapechar 49.Op Fl k Ar realm 50.Op Fl l Ar user 51.Op Fl n Ar tracefile 52.Op Fl s Ar src_addr 53.Oo 54.Ar host 55.Op Ar port 56.Oc 57.Sh DESCRIPTION 58The 59.Nm 60command 61is used to communicate with another host using the 62.Tn TELNET 63protocol. 64If 65.Nm 66is invoked without the 67.Ar host 68argument, it enters command mode, 69indicated by its prompt 70.Pq Dq Li telnet\&> . 71In this mode, it accepts and executes the commands listed below. 72If it is invoked with arguments, it performs an 73.Ic open 74command with those arguments. 75.Pp 76Options: 77.Bl -tag -width indent 78.It Fl 4 79Forces 80.Nm 81to use IPv4 addresses only. 82.It Fl 6 83Forces 84.Nm 85to use IPv6 addresses only. 86.It Fl 8 87Specifies an 8-bit data path. 88This 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. 104This causes the 105.Dv BINARY 106option to be negotiated on output. 107.It Fl N 108Prevents IP address to name lookup when destination host is given 109as an IP address. 110.It Fl S Ar tos 111Sets the IP type-of-service (TOS) option for the telnet 112connection to the value 113.Ar tos , 114which can be a numeric TOS value 115or, on systems that support it, a symbolic 116TOS name found in the 117.Pa /etc/iptos 118file. 119.It Fl X Ar atype 120Disables the 121.Ar atype 122type of authentication. 123.It Fl a 124Attempt automatic login. 125This is now the default, so this option is ignored. 126Currently, this sends the user name via the 127.Ev USER 128variable 129of the 130.Ev ENVIRON 131option if supported by the remote system. 132The name used is that of the current user as returned by 133.Xr getlogin 2 134if it agrees with the current user ID, 135otherwise it is the name associated with the user ID. 136.It Fl c 137Disables the reading of the user's 138.Pa \&.telnetrc 139file. 140(See the 141.Ic toggle skiprc 142command on this man page.) 143.It Fl d 144Sets the initial value of the 145.Ic debug 146toggle to 147.Dv TRUE . 148.It Fl e Ar escapechar 149Sets the initial 150.Nm 151escape character to 152.Ar escapechar . 153If 154.Ar escapechar 155is omitted, then 156there will be no escape character. 157.It Fl f 158If Kerberos V5 authentication is being used, the 159.Fl f 160option allows the local credentials to be forwarded to the remote system. 161.It Fl k Ar realm 162If Kerberos authentication is being used, the 163.Fl k 164option requests that 165.Nm 166obtain tickets for the remote host in 167realm 168.Ar realm 169instead of the remote host's realm, as determined by 170.Xr krb_realmofhost 3 . 171.It Fl l Ar user 172When connecting to the remote system, if the remote system 173understands the 174.Ev ENVIRON 175option, then 176.Ar user 177will be sent to the remote system as the value for the variable 178.Ev USER . 179This option implies the 180.Fl a 181option. 182This option may also be used with the 183.Ic open 184command. 185.It Fl n Ar tracefile 186Opens 187.Ar tracefile 188for recording trace information. 189See the 190.Ic set tracefile 191command below. 192.It Fl r 193Specifies a user interface similar to 194.Xr rlogin 1 . 195In this 196mode, the escape character is set to the tilde (~) character, 197unless modified by the 198.Fl e 199option. 200.It Fl s Ar src_addr 201Set the source IP address for the 202.Nm 203connection to 204.Ar src_addr , 205which can be an IP address or a host name. 206.It Fl u 207Forces 208.Nm 209to use 210.Dv AF_UNIX 211addresses only (e.g., 212.Ux 213domain sockets, accessed with a file path). 214.It Fl x 215Turns on encryption of the data stream if possible. 216This is now the default, so this option is ignored. 217.It Fl y 218Suppresses encryption of the data stream. 219.It Ar host 220Indicates the official name, an alias, or the Internet address 221of a remote host. 222If 223.Ar host 224starts with a 225.Ql / , 226.Nm 227establishes a connection to the corresponding named socket. 228.It Ar port 229Indicates a port number (address of an application). 230If a number is 231not specified, the default 232.Nm 233port is used. 234.El 235.Pp 236When in rlogin mode, a line of the form ~.\& disconnects from the 237remote host; ~ is the 238.Nm 239escape character. 240Similarly, the line ~^Z suspends the 241.Nm 242session. 243The line ~^] escapes to the normal 244.Nm 245escape prompt. 246.Pp 247Once a connection has been opened, 248.Nm 249will attempt to enable the 250.Dv TELNET LINEMODE 251option. 252If this fails, then 253.Nm 254will revert to one of two input modes: 255either \*(Lqcharacter at a time\*(Rq 256or \*(Lqold line by line\*(Rq 257depending on what the remote system supports. 258.Pp 259When 260.Dv LINEMODE 261is enabled, character processing is done on the 262local system, under the control of the remote system. 263When input 264editing or character echoing is to be disabled, the remote system 265will relay that information. 266The remote system will also relay 267changes to any special characters that happen on the remote 268system, so that they can take effect on the local system. 269.Pp 270In \*(Lqcharacter at a time\*(Rq mode, most 271text typed is immediately sent to the remote host for processing. 272.Pp 273In \*(Lqold line by line\*(Rq mode, all text is echoed locally, 274and (normally) only completed lines are sent to the remote host. 275The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used 276to turn off and on the local echo 277(this would mostly be used to enter passwords 278without the password being echoed). 279.Pp 280If the 281.Dv LINEMODE 282option is enabled, or if the 283.Ic localchars 284toggle is 285.Dv TRUE 286(the default for \*(Lqold line by line\*(Rq; see below), 287the user's 288.Ic quit , 289.Ic intr , 290and 291.Ic flush 292characters are trapped locally, and sent as 293.Tn TELNET 294protocol sequences to the remote side. 295If 296.Dv LINEMODE 297has ever been enabled, then the user's 298.Ic susp 299and 300.Ic eof 301are also sent as 302.Tn TELNET 303protocol sequences, 304and 305.Ic quit 306is sent as a 307.Dv TELNET ABORT 308instead of 309.Dv BREAK . 310There are options (see 311.Ic toggle 312.Ic autoflush 313and 314.Ic toggle 315.Ic autosynch 316below) 317which cause this action to flush subsequent output to the terminal 318(until the remote host acknowledges the 319.Tn TELNET 320sequence) and flush previous terminal input 321(in the case of 322.Ic quit 323and 324.Ic intr ) . 325.Pp 326While connected to a remote host, 327.Nm 328command mode may be entered by typing the 329.Nm 330\*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq). 331When in command mode, the normal terminal editing conventions are available. 332.Pp 333The following 334.Nm 335commands are available. 336Only enough of each command to uniquely identify it need be typed 337(this is also true for arguments to the 338.Ic mode , 339.Ic set , 340.Ic toggle , 341.Ic unset , 342.Ic slc , 343.Ic environ , 344and 345.Ic display 346commands). 347.Pp 348.Bl -tag -width "mode type" 349.It Ic auth Ar argument ... 350The auth command manipulates the information sent through the 351.Dv TELNET AUTHENTICATE 352option. 353Valid arguments for the 354.Ic auth 355command are: 356.Bl -tag -width "disable type" 357.It Ic disable Ar type 358Disables the specified type of authentication. 359To 360obtain a list of available types, use the 361.Ic auth disable ?\& 362command. 363.It Ic enable Ar type 364Enables the specified type of authentication. 365To 366obtain a list of available types, use the 367.Ic auth enable ?\& 368command. 369.It Ic status 370Lists the current status of the various types of 371authentication. 372.El 373.It Ic close 374Close a 375.Tn TELNET 376session and return to command mode. 377.It Ic display Ar argument ... 378Displays all, or some, of the 379.Ic set 380and 381.Ic toggle 382values (see below). 383.It Ic encrypt Ar argument ... 384The encrypt command manipulates the information sent through the 385.Dv TELNET ENCRYPT 386option. 387.Pp 388Valid arguments for the 389.Ic encrypt 390command are: 391.Bl -tag -width Ar 392.It Ic disable Ar type Xo 393.Op Cm input | output 394.Xc 395Disables the specified type of encryption. 396If you 397omit the input and output, both input and output 398are disabled. 399To obtain a list of available 400types, use the 401.Ic encrypt disable ?\& 402command. 403.It Ic enable Ar type Xo 404.Op Cm input | output 405.Xc 406Enables the specified type of encryption. 407If you 408omit input and output, both input and output are 409enabled. 410To obtain a list of available types, use the 411.Ic encrypt enable ?\& 412command. 413.It Ic input 414This is the same as the 415.Ic encrypt start input 416command. 417.It Ic -input 418This is the same as the 419.Ic encrypt stop input 420command. 421.It Ic output 422This is the same as the 423.Ic encrypt start output 424command. 425.It Ic -output 426This is the same as the 427.Ic encrypt stop output 428command. 429.It Ic start Op Cm input | output 430Attempts to start encryption. 431If you omit 432.Ic input 433and 434.Ic output , 435both input and output are enabled. 436To 437obtain a list of available types, use the 438.Ic encrypt enable ?\& 439command. 440.It Ic status 441Lists the current status of encryption. 442.It Ic stop Op Cm input | output 443Stops encryption. 444If you omit input and output, 445encryption is on both input and output. 446.It Ic type Ar type 447Sets the default type of encryption to be used 448with later 449.Ic encrypt start 450or 451.Ic encrypt stop 452commands. 453.El 454.It Ic environ Ar arguments ... 455The 456.Ic environ 457command is used to manipulate the 458variables that may be sent through the 459.Dv TELNET ENVIRON 460option. 461The initial set of variables is taken from the users 462environment, with only the 463.Ev DISPLAY 464and 465.Ev PRINTER 466variables being exported by default. 467The 468.Ev USER 469variable is also exported if the 470.Fl a 471or 472.Fl l 473options are used. 474.Pp 475Valid arguments for the 476.Ic environ 477command are: 478.Bl -tag -width Fl 479.It Ic define Ar variable value 480Define the variable 481.Ar variable 482to have a value of 483.Ar value . 484Any variables defined by this command are automatically exported. 485The 486.Ar value 487may be enclosed in single or double quotes so 488that tabs and spaces may be included. 489.It Ic undefine Ar variable 490Remove 491.Ar variable 492from the list of environment variables. 493.It Ic export Ar variable 494Mark the variable 495.Ar variable 496to be exported to the remote side. 497.It Ic unexport Ar variable 498Mark the variable 499.Ar variable 500to not be exported unless 501explicitly asked for by the remote side. 502.It Ic list 503List the current set of environment variables. 504Those marked with a 505.Cm * 506will be sent automatically, 507other variables will only be sent if explicitly requested. 508.It Ic ?\& 509Prints out help information for the 510.Ic environ 511command. 512.El 513.It Ic logout 514Sends the 515.Dv TELNET LOGOUT 516option to the remote side. 517This command is similar to a 518.Ic close 519command; however, if the remote side does not support the 520.Dv LOGOUT 521option, nothing happens. 522If, however, the remote side does support the 523.Dv LOGOUT 524option, this command should cause the remote side to close the 525.Tn TELNET 526connection. 527If the remote side also supports the concept of 528suspending a user's session for later reattachment, 529the logout argument indicates that you 530should terminate the session immediately. 531.It Ic mode Ar type 532.Ar Type 533is one of several options, depending on the state of the 534.Tn TELNET 535session. 536The remote host is asked for permission to go into the requested mode. 537If the remote host is capable of entering that mode, the requested 538mode will be entered. 539.Bl -tag -width Ar 540.It Ic character 541Disable the 542.Dv TELNET LINEMODE 543option, or, if the remote side does not understand the 544.Dv LINEMODE 545option, then enter \*(Lqcharacter at a time\*(Rq mode. 546.It Ic line 547Enable the 548.Dv TELNET LINEMODE 549option, or, if the remote side does not understand the 550.Dv LINEMODE 551option, then attempt to enter \*(Lqold-line-by-line\*(Rq mode. 552.It Ic isig Pq Ic \-isig 553Attempt to enable (disable) the 554.Dv TRAPSIG 555mode of the 556.Dv LINEMODE 557option. 558This requires that the 559.Dv LINEMODE 560option be enabled. 561.It Ic edit Pq Ic \-edit 562Attempt to enable (disable) the 563.Dv EDIT 564mode of the 565.Dv LINEMODE 566option. 567This requires that the 568.Dv LINEMODE 569option be enabled. 570.It Ic softtabs Pq Ic \-softtabs 571Attempt to enable (disable) the 572.Dv SOFT_TAB 573mode of the 574.Dv LINEMODE 575option. 576This requires that the 577.Dv LINEMODE 578option be enabled. 579.It Ic litecho Pq Ic \-litecho 580Attempt to enable (disable) the 581.Dv LIT_ECHO 582mode of the 583.Dv LINEMODE 584option. 585This requires that the 586.Dv LINEMODE 587option be enabled. 588.It Ic ?\& 589Prints out help information for the 590.Ic mode 591command. 592.El 593.It Xo 594.Ic open 595.Op Fl l Ar user 596.Op Ar host 597.Op Oo Fl /+ Oc Ns Ar port 598.Xc 599Open a connection to the named host. 600If no port number 601is specified, 602.Nm 603will attempt to contact a 604.Tn TELNET 605server at the default port. 606The host specification may be either a host name (see 607.Xr hosts 5 ) , 608an Internet address specified in the \*(Lqdot notation\*(Rq (see 609.Xr inet 3 ) , 610or IPv6 host name or IPv6 coloned-hexadecimal addreess. 611The 612.Fl l 613option may be used to specify the user name 614to be passed to the remote system via the 615.Ev ENVIRON 616option. 617When connecting to a non-standard port, 618.Nm 619omits any automatic initiation of 620.Tn TELNET 621options. 622When the port number is preceded by a minus sign, 623the initial option negotiation is done. 624When, however, the port number 625is preceded by a plus sign, 626any option negotiation and understanding is prohibited, 627making telnet dumb client for POP3/SMTP/NNTP/HTTP-like 628protocols with any data including 629.Tn TELNET 630IAC character (0xff). 631After establishing a connection, the file 632.Pa \&.telnetrc 633in the 634users home directory is opened. 635Lines beginning with a # are 636comment lines. 637Blank lines are ignored. 638Lines that begin 639without white space are the start of a machine entry. 640The 641first thing on the line is the name of the machine that is 642being connected to. 643It may be the hostname or numeric address specified as the argument 644.Ar host , 645the canonical name of that string as determined by 646.Xr getaddrinfo 3 , 647or the string 648.Dq Li DEFAULT 649indicating all hosts. 650The rest of the line, and successive 651lines that begin with white space are assumed to be 652.Nm 653commands and are processed as if they had been typed 654in manually to the 655.Nm 656command prompt. 657.It Ic quit 658Close any open 659.Tn TELNET 660session and exit 661.Nm . 662An end of file (in command mode) will also close a session and exit. 663.It Ic send Ar arguments 664Sends one or more special character sequences to the remote host. 665The following are the arguments which may be specified 666(more than one argument may be specified at a time): 667.Pp 668.Bl -tag -width escape 669.It Ic abort 670Sends the 671.Dv TELNET ABORT 672(Abort 673processes) 674sequence. 675.It Ic ao 676Sends the 677.Dv TELNET AO 678(Abort Output) sequence, which should cause the remote system to flush 679all output 680.Em from 681the remote system 682.Em to 683the user's terminal. 684.It Ic ayt 685Sends the 686.Dv TELNET AYT 687(Are You There) 688sequence, to which the remote system may or may not choose to respond. 689.It Ic brk 690Sends the 691.Dv TELNET BRK 692(Break) sequence, which may have significance to the remote 693system. 694.It Ic ec 695Sends the 696.Dv TELNET EC 697(Erase Character) 698sequence, which should cause the remote system to erase the last character 699entered. 700.It Ic el 701Sends the 702.Dv TELNET EL 703(Erase Line) 704sequence, which should cause the remote system to erase the line currently 705being entered. 706.It Ic eof 707Sends the 708.Dv TELNET EOF 709(End Of File) 710sequence. 711.It Ic eor 712Sends the 713.Dv TELNET EOR 714(End of Record) 715sequence. 716.It Ic escape 717Sends the current 718.Nm 719escape character (initially \*(Lq^\*(Rq). 720.It Ic ga 721Sends the 722.Dv TELNET GA 723(Go Ahead) 724sequence, which likely has no significance to the remote system. 725.It Ic getstatus 726If the remote side supports the 727.Dv TELNET STATUS 728command, 729.Ic getstatus 730will send the subnegotiation to request that the server send 731its current option status. 732.It Ic ip 733Sends the 734.Dv TELNET IP 735(Interrupt Process) sequence, which should cause the remote 736system to abort the currently running process. 737.It Ic nop 738Sends the 739.Dv TELNET NOP 740(No OPeration) 741sequence. 742.It Ic susp 743Sends the 744.Dv TELNET SUSP 745(SUSPend process) 746sequence. 747.It Ic synch 748Sends the 749.Dv TELNET SYNCH 750sequence. 751This sequence causes the remote system to discard all previously typed 752(but not yet read) input. 753This sequence is sent as 754.Tn TCP 755urgent 756data (and may not work if the remote system is a 757.Bx 4.2 758system -- if 759it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal). 760.It Ic do Ar cmd 761.It Ic dont Ar cmd 762.It Ic will Ar cmd 763.It Ic wont Ar cmd 764Sends the 765.Dv TELNET DO 766.Ar cmd 767sequence. 768.Ar Cmd 769can be either a decimal number between 0 and 255, 770or a symbolic name for a specific 771.Dv TELNET 772command. 773.Ar Cmd 774can also be either 775.Ic help 776or 777.Ic ?\& 778to print out help information, including 779a list of known symbolic names. 780.It Ic ?\& 781Prints out help information for the 782.Ic send 783command. 784.El 785.It Ic set Ar argument value 786.It Ic unset Ar argument value 787The 788.Ic set 789command will set any one of a number of 790.Nm 791variables to a specific value or to 792.Dv TRUE . 793The special value 794.Ic off 795turns off the function associated with 796the variable, this is equivalent to using the 797.Ic unset 798command. 799The 800.Ic unset 801command will disable or set to 802.Dv FALSE 803any of the specified functions. 804The values of variables may be interrogated with the 805.Ic display 806command. 807The variables which may be set or unset, but not toggled, are 808listed here. 809In addition, any of the variables for the 810.Ic toggle 811command may be explicitly set or unset using 812the 813.Ic set 814and 815.Ic unset 816commands. 817.Bl -tag -width escape 818.It Ic ayt 819If 820.Tn TELNET 821is in localchars mode, or 822.Dv LINEMODE 823is enabled, and the status character is typed, a 824.Dv TELNET AYT 825sequence (see 826.Ic send ayt 827preceding) is sent to the 828remote host. 829The initial value for the \*(LqAre You There\*(Rq 830character is the terminal's status character. 831.It Ic echo 832This is the value (initially \*(Lq^E\*(Rq) which, when in 833\*(Lqline by line\*(Rq mode, toggles between doing local echoing 834of entered characters (for normal processing), and suppressing 835echoing of entered characters (for entering, say, a password). 836.It Ic eof 837If 838.Nm 839is operating in 840.Dv LINEMODE 841or \*(Lqold line by line\*(Rq mode, entering this character 842as the first character on a line will cause this character to be 843sent to the remote system. 844The initial value of the eof character is taken to be the terminal's 845.Ic eof 846character. 847.It Ic erase 848If 849.Nm 850is in 851.Ic localchars 852mode (see 853.Ic toggle 854.Ic localchars 855below), 856.Sy and 857if 858.Nm 859is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 860character is typed, a 861.Dv TELNET EC 862sequence (see 863.Ic send 864.Ic ec 865above) 866is sent to the remote system. 867The initial value for the erase character is taken to be 868the terminal's 869.Ic erase 870character. 871.It Ic escape 872This is the 873.Nm 874escape character (initially \*(Lq^[\*(Rq) which causes entry 875into 876.Nm 877command mode (when connected to a remote system). 878.It Ic flushoutput 879If 880.Nm 881is in 882.Ic localchars 883mode (see 884.Ic toggle 885.Ic localchars 886below) 887and the 888.Ic flushoutput 889character is typed, a 890.Dv TELNET AO 891sequence (see 892.Ic send 893.Ic ao 894above) 895is sent to the remote host. 896The initial value for the flush character is taken to be 897the terminal's 898.Ic flush 899character. 900.It Ic forw1 901.It Ic forw2 902If 903.Nm 904is operating in 905.Dv LINEMODE , 906these are the 907characters that, when typed, cause partial lines to be 908forwarded to the remote system. 909The initial value for 910the forwarding characters are taken from the terminal's 911eol and eol2 characters. 912.It Ic interrupt 913If 914.Nm 915is in 916.Ic localchars 917mode (see 918.Ic toggle 919.Ic localchars 920below) 921and the 922.Ic interrupt 923character is typed, a 924.Dv TELNET IP 925sequence (see 926.Ic send 927.Ic ip 928above) 929is sent to the remote host. 930The initial value for the interrupt character is taken to be 931the terminal's 932.Ic intr 933character. 934.It Ic kill 935If 936.Nm 937is in 938.Ic localchars 939mode (see 940.Ic toggle 941.Ic localchars 942below), 943.Ic and 944if 945.Nm 946is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 947character is typed, a 948.Dv TELNET EL 949sequence (see 950.Ic send 951.Ic el 952above) 953is sent to the remote system. 954The initial value for the kill character is taken to be 955the terminal's 956.Ic kill 957character. 958.It Ic lnext 959If 960.Nm 961is operating in 962.Dv LINEMODE 963or \*(Lqold line by line\*(Rq mode, then this character is taken to 964be the terminal's 965.Ic lnext 966character. 967The initial value for the lnext character is taken to be 968the terminal's 969.Ic lnext 970character. 971.It Ic quit 972If 973.Nm 974is in 975.Ic localchars 976mode (see 977.Ic toggle 978.Ic localchars 979below) 980and the 981.Ic quit 982character is typed, a 983.Dv TELNET BRK 984sequence (see 985.Ic send 986.Ic brk 987above) 988is sent to the remote host. 989The initial value for the quit character is taken to be 990the terminal's 991.Ic quit 992character. 993.It Ic reprint 994If 995.Nm 996is operating in 997.Dv LINEMODE 998or \*(Lqold line by line\*(Rq mode, then this character is taken to 999be the terminal's 1000.Ic reprint 1001character. 1002The initial value for the reprint character is taken to be 1003the terminal's 1004.Ic reprint 1005character. 1006.It Ic rlogin 1007This is the rlogin escape character. 1008If set, the normal 1009.Nm 1010escape character is ignored unless it is 1011preceded by this character at the beginning of a line. 1012This character, at the beginning of a line followed by 1013a "." closes the connection; when followed by a ^Z it 1014suspends the 1015.Nm 1016command. 1017The initial state is to 1018disable the 1019.Nm rlogin 1020escape character. 1021.It Ic start 1022If the 1023.Dv TELNET TOGGLE-FLOW-CONTROL 1024option has been enabled, 1025then this character is taken to 1026be the terminal's 1027.Ic start 1028character. 1029The initial value for the start character is taken to be 1030the terminal's 1031.Ic start 1032character. 1033.It Ic stop 1034If the 1035.Dv TELNET TOGGLE-FLOW-CONTROL 1036option has been enabled, 1037then this character is taken to 1038be the terminal's 1039.Ic stop 1040character. 1041The initial value for the stop character is taken to be 1042the terminal's 1043.Ic stop 1044character. 1045.It Ic susp 1046If 1047.Nm 1048is in 1049.Ic localchars 1050mode, or 1051.Dv LINEMODE 1052is enabled, and the 1053.Ic suspend 1054character is typed, a 1055.Dv TELNET SUSP 1056sequence (see 1057.Ic send 1058.Ic susp 1059above) 1060is sent to the remote host. 1061The initial value for the suspend character is taken to be 1062the terminal's 1063.Ic suspend 1064character. 1065.It Ic tracefile 1066This is the file to which the output, caused by 1067.Ic netdata 1068or 1069.Ic option 1070tracing being 1071.Dv TRUE , 1072will be written. 1073If it is set to 1074.Dq Fl , 1075then tracing information will be written to standard output (the default). 1076.It Ic worderase 1077If 1078.Nm 1079is operating in 1080.Dv LINEMODE 1081or \*(Lqold line by line\*(Rq mode, then this character is taken to 1082be the terminal's 1083.Ic worderase 1084character. 1085The initial value for the worderase character is taken to be 1086the terminal's 1087.Ic worderase 1088character. 1089.It Ic ?\& 1090Displays the legal 1091.Ic set 1092.Pq Ic unset 1093commands. 1094.El 1095.It Ic opie Ar sequence challenge 1096The 1097.Ic opie 1098command computes a response to the OPIE challenge. 1099.It Ic slc Ar state 1100The 1101.Ic slc 1102command (Set Local Characters) is used to set 1103or change the state of the special 1104characters when the 1105.Dv TELNET LINEMODE 1106option has 1107been enabled. 1108Special characters are characters that get 1109mapped to 1110.Tn TELNET 1111commands sequences (like 1112.Ic ip 1113or 1114.Ic quit ) 1115or line editing characters (like 1116.Ic erase 1117and 1118.Ic kill ) . 1119By default, the local special characters are exported. 1120.Bl -tag -width Fl 1121.It Ic check 1122Verify the current settings for the current special characters. 1123The remote side is requested to send all the current special 1124character settings, and if there are any discrepancies with 1125the local side, the local side will switch to the remote value. 1126.It Ic export 1127Switch to the local defaults for the special characters. 1128The 1129local default characters are those of the local terminal at 1130the time when 1131.Nm 1132was started. 1133.It Ic import 1134Switch to the remote defaults for the special characters. 1135The remote default characters are those of the remote system 1136at the time when the 1137.Tn TELNET 1138connection was established. 1139.It Ic ?\& 1140Prints out help information for the 1141.Ic slc 1142command. 1143.El 1144.It Ic status 1145Show the current status of 1146.Nm . 1147This includes the peer one is connected to, as well 1148as the current mode. 1149.It Ic toggle Ar arguments ... 1150Toggle (between 1151.Dv TRUE 1152and 1153.Dv FALSE ) 1154various flags that control how 1155.Nm 1156responds to events. 1157These flags may be set explicitly to 1158.Dv TRUE 1159or 1160.Dv FALSE 1161using the 1162.Ic set 1163and 1164.Ic unset 1165commands listed above. 1166More than one argument may be specified. 1167The state of these flags may be interrogated with the 1168.Ic display 1169command. 1170Valid arguments are: 1171.Bl -tag -width Ar 1172.It Ic authdebug 1173Turns on debugging information for the authentication code. 1174.It Ic autoflush 1175If 1176.Ic autoflush 1177and 1178.Ic localchars 1179are both 1180.Dv TRUE , 1181then when the 1182.Ic ao , 1183or 1184.Ic quit 1185characters are recognized (and transformed into 1186.Tn TELNET 1187sequences; see 1188.Ic set 1189above for details), 1190.Nm 1191refuses to display any data on the user's terminal 1192until the remote system acknowledges (via a 1193.Dv TELNET TIMING MARK 1194option) 1195that it has processed those 1196.Tn TELNET 1197sequences. 1198The initial value for this toggle is 1199.Dv TRUE 1200if the terminal user had not 1201done an "stty noflsh", otherwise 1202.Dv FALSE 1203(see 1204.Xr stty 1 ) . 1205.It Ic autodecrypt 1206When the 1207.Dv TELNET ENCRYPT 1208option is negotiated, by 1209default the actual encryption (decryption) of the data 1210stream does not start automatically. 1211The autoencrypt 1212(autodecrypt) command states that encryption of the 1213output (input) stream should be enabled as soon as 1214possible. 1215.It Ic autologin 1216If the remote side supports the 1217.Dv TELNET AUTHENTICATION 1218option 1219.Nm 1220attempts to use it to perform automatic authentication. 1221If the 1222.Dv AUTHENTICATION 1223option is not supported, the user's login 1224name are propagated through the 1225.Dv TELNET ENVIRON 1226option. 1227This command is the same as specifying 1228.Fl a 1229option on the 1230.Ic open 1231command. 1232.It Ic autosynch 1233If 1234.Ic autosynch 1235and 1236.Ic localchars 1237are both 1238.Dv TRUE , 1239then when either the 1240.Ic intr 1241or 1242.Ic quit 1243characters is typed (see 1244.Ic set 1245above for descriptions of the 1246.Ic intr 1247and 1248.Ic quit 1249characters), the resulting 1250.Tn TELNET 1251sequence sent is followed by the 1252.Dv TELNET SYNCH 1253sequence. 1254This procedure 1255.Ic should 1256cause the remote system to begin throwing away all previously 1257typed input until both of the 1258.Tn TELNET 1259sequences have been read and acted upon. 1260The initial value of this toggle is 1261.Dv FALSE . 1262.It Ic binary 1263Enable or disable the 1264.Dv TELNET BINARY 1265option on both input and output. 1266.It Ic inbinary 1267Enable or disable the 1268.Dv TELNET BINARY 1269option on input. 1270.It Ic outbinary 1271Enable or disable the 1272.Dv TELNET BINARY 1273option on output. 1274.It Ic crlf 1275If this is 1276.Dv TRUE , 1277then carriage returns will be sent as 1278.Li <CR><LF> . 1279If this is 1280.Dv FALSE , 1281then carriage returns will be send as 1282.Li <CR><NUL> . 1283The initial value for this toggle is 1284.Dv FALSE . 1285.It Ic crmod 1286Toggle carriage return mode. 1287When this mode is enabled, most carriage return characters received from 1288the remote host will be mapped into a carriage return followed by 1289a line feed. 1290This mode does not affect those characters typed by the user, only 1291those received from the remote host. 1292This mode is not very useful unless the remote host 1293only sends carriage return, but never line feed. 1294The initial value for this toggle is 1295.Dv FALSE . 1296.It Ic debug 1297Toggles socket level debugging (useful only to the 1298.Ic super user ) . 1299The initial value for this toggle is 1300.Dv FALSE . 1301.It Ic encdebug 1302Turns on debugging information for the encryption code. 1303.It Ic localchars 1304If this is 1305.Dv TRUE , 1306then the 1307.Ic flush , 1308.Ic interrupt , 1309.Ic quit , 1310.Ic erase , 1311and 1312.Ic kill 1313characters (see 1314.Ic set 1315above) are recognized locally, and transformed into (hopefully) appropriate 1316.Tn TELNET 1317control sequences 1318(respectively 1319.Ic ao , 1320.Ic ip , 1321.Ic brk , 1322.Ic ec , 1323and 1324.Ic el ; 1325see 1326.Ic send 1327above). 1328The initial value for this toggle is 1329.Dv TRUE 1330in \*(Lqold line by line\*(Rq mode, 1331and 1332.Dv FALSE 1333in \*(Lqcharacter at a time\*(Rq mode. 1334When the 1335.Dv LINEMODE 1336option is enabled, the value of 1337.Ic localchars 1338is ignored, and assumed to always be 1339.Dv TRUE . 1340If 1341.Dv LINEMODE 1342has ever been enabled, then 1343.Ic quit 1344is sent as 1345.Ic abort , 1346and 1347.Ic eof 1348and 1349.Ic suspend 1350are sent as 1351.Ic eof 1352and 1353.Ic susp 1354(see 1355.Ic send 1356above). 1357.It Ic netdata 1358Toggles the display of all network data (in hexadecimal format). 1359The initial value for this toggle is 1360.Dv FALSE . 1361.It Ic options 1362Toggles the display of some internal 1363.Nm 1364protocol processing (having to do with 1365.Tn TELNET 1366options). 1367The initial value for this toggle is 1368.Dv FALSE . 1369.It Ic prettydump 1370When the 1371.Ic netdata 1372toggle is enabled, if 1373.Ic prettydump 1374is enabled the output from the 1375.Ic netdata 1376command will be formatted in a more user readable format. 1377Spaces are put between each character in the output, and the 1378beginning of any 1379.Nm 1380escape sequence is preceded by a '*' to aid in locating them. 1381.It Ic skiprc 1382When the skiprc toggle is 1383.Dv TRUE , 1384.Nm 1385skips the reading of the 1386.Pa \&.telnetrc 1387file in the users home 1388directory when connections are opened. 1389The initial 1390value for this toggle is 1391.Dv FALSE . 1392.It Ic termdata 1393Toggles the display of all terminal data (in hexadecimal format). 1394The initial value for this toggle is 1395.Dv FALSE . 1396.It Ic verbose_encrypt 1397When the 1398.Ic verbose_encrypt 1399toggle is 1400.Dv TRUE , 1401.Nm 1402prints out a message each time encryption is enabled or 1403disabled. 1404The initial value for this toggle is 1405.Dv FALSE . 1406.It Ic ?\& 1407Displays the legal 1408.Ic toggle 1409commands. 1410.El 1411.It Ic z 1412Suspend 1413.Nm . 1414This command only works when the user is using the 1415.Xr csh 1 . 1416.It Ic \&! Op Ar command 1417Execute a single command in a subshell on the local 1418system. 1419If 1420.Ar command 1421is omitted, then an interactive 1422subshell is invoked. 1423.It Ic ?\& Op Ar command 1424Get help. 1425With no arguments, 1426.Nm 1427prints a help summary. 1428If 1429.Ar command 1430is specified, 1431.Nm 1432will print the help information for just that command. 1433.El 1434.Sh ENVIRONMENT 1435.Nm 1436uses at least the 1437.Ev HOME , 1438.Ev SHELL , 1439.Ev DISPLAY , 1440and 1441.Ev TERM 1442environment variables. 1443Other environment variables may be propagated 1444to the other side via the 1445.Dv TELNET ENVIRON 1446option. 1447.Sh FILES 1448.Bl -tag -width ~/.telnetrc -compact 1449.It Pa ~/.telnetrc 1450user customized telnet startup values 1451.El 1452.Sh SEE ALSO 1453.Xr rlogin 1 , 1454.Xr rsh 1 , 1455.Xr hosts 5 , 1456.Xr nologin 5 , 1457.Xr telnetd 8 1458.Sh HISTORY 1459The 1460.Nm 1461command appeared in 1462.Bx 4.2 . 1463.Pp 1464IPv6 support was added by WIDE/KAME project. 1465.Sh NOTES 1466On some remote systems, echo has to be turned off manually when in 1467\*(Lqold line by line\*(Rq mode. 1468.Pp 1469In \*(Lqold line by line\*(Rq mode or 1470.Dv LINEMODE 1471the terminal's 1472.Ic eof 1473character is only recognized (and sent to the remote system) 1474when it is the first character on a line. 1475