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 B Ar baudrate 47.Op Fl S Ar tos 48.Op Fl X Ar authtype 49.Op Fl e Ar escapechar 50.Op Fl k Ar realm 51.Op Fl l Ar user 52.Op Fl n Ar tracefile 53.Op Fl s Ar src_addr 54.Oo 55.Ar host 56.Op Ar port 57.Oc 58.Sh DESCRIPTION 59The 60.Nm 61command 62is used to communicate with another host using the 63.Tn TELNET 64protocol. 65If 66.Nm 67is invoked without the 68.Ar host 69argument, it enters command mode, 70indicated by its prompt 71.Pq Dq Li telnet\&> . 72In this mode, it accepts and executes the commands listed below. 73If it is invoked with arguments, it performs an 74.Ic open 75command with those arguments. 76.Pp 77Options: 78.Bl -tag -width indent 79.It Fl 4 80Forces 81.Nm 82to use IPv4 addresses only. 83.It Fl 6 84Forces 85.Nm 86to use IPv6 addresses only. 87.It Fl 8 88Specifies an 8-bit data path. 89This causes an attempt to 90negotiate the 91.Dv TELNET BINARY 92option on both input and output. 93.It Fl B Ar baudrate 94Sets the baud rate to 95.Ar baudrate . 96.It Fl E 97Stops any character from being recognized as an escape character. 98.It Fl F 99If Kerberos V5 authentication is being used, the 100.Fl F 101option allows the local credentials to be forwarded 102to the remote system, including any credentials that 103have already been forwarded into the local environment. 104.It Fl K 105Specifies no automatic login to the remote system. 106.It Fl L 107Specifies an 8-bit data path on output. 108This causes the 109.Dv BINARY 110option to be negotiated on output. 111.It Fl N 112Prevents IP address to name lookup when destination host is given 113as an IP address. 114.It Fl S Ar tos 115Sets the IP type-of-service (TOS) option for the telnet 116connection to the value 117.Ar tos , 118which can be a numeric TOS value 119or, on systems that support it, a symbolic 120TOS name found in the 121.Pa /etc/iptos 122file. 123.It Fl X Ar atype 124Disables the 125.Ar atype 126type of authentication. 127.It Fl a 128Attempt automatic login. 129This is now the default, so this option is ignored. 130Currently, this sends the user name via the 131.Ev USER 132variable 133of the 134.Ev ENVIRON 135option if supported by the remote system. 136The name used is that of the current user as returned by 137.Xr getlogin 2 138if it agrees with the current user ID, 139otherwise it is the name associated with the user ID. 140.It Fl c 141Disables the reading of the user's 142.Pa \&.telnetrc 143file. 144(See the 145.Ic toggle skiprc 146command on this man page.) 147.It Fl d 148Sets the initial value of the 149.Ic debug 150toggle to 151.Dv TRUE . 152.It Fl e Ar escapechar 153Sets the initial 154.Nm 155escape character to 156.Ar escapechar . 157If 158.Ar escapechar 159is omitted, then 160there will be no escape character. 161.It Fl f 162If Kerberos V5 authentication is being used, the 163.Fl f 164option allows the local credentials to be forwarded to the remote system. 165.It Fl k Ar realm 166If Kerberos authentication is being used, the 167.Fl k 168option requests that 169.Nm 170obtain tickets for the remote host in 171realm 172.Ar realm 173instead of the remote host's realm, as determined by 174.Xr krb_realmofhost 3 . 175.It Fl l Ar user 176When connecting to the remote system, if the remote system 177understands the 178.Ev ENVIRON 179option, then 180.Ar user 181will be sent to the remote system as the value for the variable 182.Ev USER . 183This option implies the 184.Fl a 185option. 186This option may also be used with the 187.Ic open 188command. 189.It Fl n Ar tracefile 190Opens 191.Ar tracefile 192for recording trace information. 193See the 194.Ic set tracefile 195command below. 196.It Fl r 197Specifies a user interface similar to 198.Xr rlogin 1 . 199In this 200mode, the escape character is set to the tilde (~) character, 201unless modified by the 202.Fl e 203option. 204.It Fl s Ar src_addr 205Set the source IP address for the 206.Nm 207connection to 208.Ar src_addr , 209which can be an IP address or a host name. 210.It Fl u 211Forces 212.Nm 213to use 214.Dv AF_UNIX 215addresses only (e.g., 216.Ux 217domain sockets, accessed with a file path). 218.It Fl x 219Turns on encryption of the data stream if possible. 220This is now the default, so this option is ignored. 221.It Fl y 222Suppresses encryption of the data stream. 223.It Ar host 224Indicates the official name, an alias, or the Internet address 225of a remote host. 226If 227.Ar host 228starts with a 229.Ql / , 230.Nm 231establishes a connection to the corresponding named socket. 232.It Ar port 233Indicates a port number (address of an application). 234If a number is 235not specified, the default 236.Nm 237port is used. 238.El 239.Pp 240When in rlogin mode, a line of the form ~.\& disconnects from the 241remote host; ~ is the 242.Nm 243escape character. 244Similarly, the line ~^Z suspends the 245.Nm 246session. 247The line ~^] escapes to the normal 248.Nm 249escape prompt. 250.Pp 251Once a connection has been opened, 252.Nm 253will attempt to enable the 254.Dv TELNET LINEMODE 255option. 256If this fails, then 257.Nm 258will revert to one of two input modes: 259either \*(Lqcharacter at a time\*(Rq 260or \*(Lqold line by line\*(Rq 261depending on what the remote system supports. 262.Pp 263When 264.Dv LINEMODE 265is enabled, character processing is done on the 266local system, under the control of the remote system. 267When input 268editing or character echoing is to be disabled, the remote system 269will relay that information. 270The remote system will also relay 271changes to any special characters that happen on the remote 272system, so that they can take effect on the local system. 273.Pp 274In \*(Lqcharacter at a time\*(Rq mode, most 275text typed is immediately sent to the remote host for processing. 276.Pp 277In \*(Lqold line by line\*(Rq mode, all text is echoed locally, 278and (normally) only completed lines are sent to the remote host. 279The \*(Lqlocal echo character\*(Rq (initially \*(Lq^E\*(Rq) may be used 280to turn off and on the local echo 281(this would mostly be used to enter passwords 282without the password being echoed). 283.Pp 284If the 285.Dv LINEMODE 286option is enabled, or if the 287.Ic localchars 288toggle is 289.Dv TRUE 290(the default for \*(Lqold line by line\*(Rq; see below), 291the user's 292.Ic quit , 293.Ic intr , 294and 295.Ic flush 296characters are trapped locally, and sent as 297.Tn TELNET 298protocol sequences to the remote side. 299If 300.Dv LINEMODE 301has ever been enabled, then the user's 302.Ic susp 303and 304.Ic eof 305are also sent as 306.Tn TELNET 307protocol sequences, 308and 309.Ic quit 310is sent as a 311.Dv TELNET ABORT 312instead of 313.Dv BREAK . 314There are options (see 315.Ic toggle 316.Ic autoflush 317and 318.Ic toggle 319.Ic autosynch 320below) 321which cause this action to flush subsequent output to the terminal 322(until the remote host acknowledges the 323.Tn TELNET 324sequence) and flush previous terminal input 325(in the case of 326.Ic quit 327and 328.Ic intr ) . 329.Pp 330While connected to a remote host, 331.Nm 332command mode may be entered by typing the 333.Nm 334\*(Lqescape character\*(Rq (initially \*(Lq^]\*(Rq). 335When in command mode, the normal terminal editing conventions are available. 336.Pp 337The following 338.Nm 339commands are available. 340Only enough of each command to uniquely identify it need be typed 341(this is also true for arguments to the 342.Ic mode , 343.Ic set , 344.Ic toggle , 345.Ic unset , 346.Ic slc , 347.Ic environ , 348and 349.Ic display 350commands). 351.Bl -tag -width "mode type" 352.It Ic auth Ar argument ... 353The auth command manipulates the information sent through the 354.Dv TELNET AUTHENTICATE 355option. 356Valid arguments for the 357.Ic auth 358command are: 359.Bl -tag -width "disable type" 360.It Ic disable Ar type 361Disables the specified type of authentication. 362To 363obtain a list of available types, use the 364.Ic auth disable ?\& 365command. 366.It Ic enable Ar type 367Enables the specified type of authentication. 368To 369obtain a list of available types, use the 370.Ic auth enable ?\& 371command. 372.It Ic status 373Lists the current status of the various types of 374authentication. 375.El 376.It Ic close 377Close a 378.Tn TELNET 379session and return to command mode. 380.It Ic display Ar argument ... 381Displays all, or some, of the 382.Ic set 383and 384.Ic toggle 385values (see below). 386.It Ic encrypt Ar argument ... 387The encrypt command manipulates the information sent through the 388.Dv TELNET ENCRYPT 389option. 390.Pp 391Valid arguments for the 392.Ic encrypt 393command are: 394.Bl -tag -width Ar 395.It Ic disable Ar type Xo 396.Op Cm input | output 397.Xc 398Disables the specified type of encryption. 399If you 400omit the input and output, both input and output 401are disabled. 402To obtain a list of available 403types, use the 404.Ic encrypt disable ?\& 405command. 406.It Ic enable Ar type Xo 407.Op Cm input | output 408.Xc 409Enables the specified type of encryption. 410If you 411omit input and output, both input and output are 412enabled. 413To obtain a list of available types, use the 414.Ic encrypt enable ?\& 415command. 416.It Ic input 417This is the same as the 418.Ic encrypt start input 419command. 420.It Ic -input 421This is the same as the 422.Ic encrypt stop input 423command. 424.It Ic output 425This is the same as the 426.Ic encrypt start output 427command. 428.It Ic -output 429This is the same as the 430.Ic encrypt stop output 431command. 432.It Ic start Op Cm input | output 433Attempts to start encryption. 434If you omit 435.Ic input 436and 437.Ic output , 438both input and output are enabled. 439To 440obtain a list of available types, use the 441.Ic encrypt enable ?\& 442command. 443.It Ic status 444Lists the current status of encryption. 445.It Ic stop Op Cm input | output 446Stops encryption. 447If you omit input and output, 448encryption is on both input and output. 449.It Ic type Ar type 450Sets the default type of encryption to be used 451with later 452.Ic encrypt start 453or 454.Ic encrypt stop 455commands. 456.El 457.It Ic environ Ar arguments ... 458The 459.Ic environ 460command is used to manipulate the 461variables that may be sent through the 462.Dv TELNET ENVIRON 463option. 464The initial set of variables is taken from the users 465environment, with only the 466.Ev DISPLAY 467and 468.Ev PRINTER 469variables being exported by default. 470The 471.Ev USER 472variable is also exported if the 473.Fl a 474or 475.Fl l 476options are used. 477.Pp 478Valid arguments for the 479.Ic environ 480command are: 481.Bl -tag -width Fl 482.It Ic define Ar variable value 483Define the variable 484.Ar variable 485to have a value of 486.Ar value . 487Any variables defined by this command are automatically exported. 488The 489.Ar value 490may be enclosed in single or double quotes so 491that tabs and spaces may be included. 492.It Ic undefine Ar variable 493Remove 494.Ar variable 495from the list of environment variables. 496.It Ic export Ar variable 497Mark the variable 498.Ar variable 499to be exported to the remote side. 500.It Ic unexport Ar variable 501Mark the variable 502.Ar variable 503to not be exported unless 504explicitly asked for by the remote side. 505.It Ic list 506List the current set of environment variables. 507Those marked with a 508.Cm * 509will be sent automatically, 510other variables will only be sent if explicitly requested. 511.It Ic ?\& 512Prints out help information for the 513.Ic environ 514command. 515.El 516.It Ic logout 517Sends the 518.Dv TELNET LOGOUT 519option to the remote side. 520This command is similar to a 521.Ic close 522command; however, if the remote side does not support the 523.Dv LOGOUT 524option, nothing happens. 525If, however, the remote side does support the 526.Dv LOGOUT 527option, this command should cause the remote side to close the 528.Tn TELNET 529connection. 530If the remote side also supports the concept of 531suspending a user's session for later reattachment, 532the logout argument indicates that you 533should terminate the session immediately. 534.It Ic mode Ar type 535.Ar Type 536is one of several options, depending on the state of the 537.Tn TELNET 538session. 539The remote host is asked for permission to go into the requested mode. 540If the remote host is capable of entering that mode, the requested 541mode will be entered. 542.Bl -tag -width Ar 543.It Ic character 544Disable the 545.Dv TELNET LINEMODE 546option, or, if the remote side does not understand the 547.Dv LINEMODE 548option, then enter \*(Lqcharacter at a time\*(Rq mode. 549.It Ic line 550Enable the 551.Dv TELNET LINEMODE 552option, or, if the remote side does not understand the 553.Dv LINEMODE 554option, then attempt to enter \*(Lqold-line-by-line\*(Rq mode. 555.It Ic isig Pq Ic \-isig 556Attempt to enable (disable) the 557.Dv TRAPSIG 558mode of the 559.Dv LINEMODE 560option. 561This requires that the 562.Dv LINEMODE 563option be enabled. 564.It Ic edit Pq Ic \-edit 565Attempt to enable (disable) the 566.Dv EDIT 567mode of the 568.Dv LINEMODE 569option. 570This requires that the 571.Dv LINEMODE 572option be enabled. 573.It Ic softtabs Pq Ic \-softtabs 574Attempt to enable (disable) the 575.Dv SOFT_TAB 576mode of the 577.Dv LINEMODE 578option. 579This requires that the 580.Dv LINEMODE 581option be enabled. 582.It Ic litecho Pq Ic \-litecho 583Attempt to enable (disable) the 584.Dv LIT_ECHO 585mode of the 586.Dv LINEMODE 587option. 588This requires that the 589.Dv LINEMODE 590option be enabled. 591.It Ic ?\& 592Prints out help information for the 593.Ic mode 594command. 595.El 596.It Xo 597.Ic open 598.Op Fl l Ar user 599.Op Ar host 600.Op Oo Fl /+ Oc Ns Ar port 601.Xc 602Open a connection to the named host. 603If no port number 604is specified, 605.Nm 606will attempt to contact a 607.Tn TELNET 608server at the default port. 609The host specification may be either a host name (see 610.Xr hosts 5 ) , 611an Internet address specified in the \*(Lqdot notation\*(Rq (see 612.Xr inet 3 ) , 613or IPv6 host name or IPv6 coloned-hexadecimal addreess. 614The 615.Fl l 616option may be used to specify the user name 617to be passed to the remote system via the 618.Ev ENVIRON 619option. 620When connecting to a non-standard port, 621.Nm 622omits any automatic initiation of 623.Tn TELNET 624options. 625When the port number is preceded by a minus sign, 626the initial option negotiation is done. 627When, however, the port number 628is preceded by a plus sign, 629any option negotiation and understanding is prohibited, 630making telnet dumb client for POP3/SMTP/NNTP/HTTP-like 631protocols with any data including 632.Tn TELNET 633IAC character (0xff). 634After establishing a connection, the file 635.Pa \&.telnetrc 636in the 637users home directory is opened. 638Lines beginning with a # are 639comment lines. 640Blank lines are ignored. 641Lines that begin 642without white space are the start of a machine entry. 643The 644first thing on the line is the name of the machine that is 645being connected to. 646It may be the hostname or numeric address specified as the argument 647.Ar host , 648the canonical name of that string as determined by 649.Xr getaddrinfo 3 , 650or the string 651.Dq Li DEFAULT 652indicating all hosts. 653The rest of the line, and successive 654lines that begin with white space are assumed to be 655.Nm 656commands and are processed as if they had been typed 657in manually to the 658.Nm 659command prompt. 660.It Ic quit 661Close any open 662.Tn TELNET 663session and exit 664.Nm . 665An end of file (in command mode) will also close a session and exit. 666.It Ic send Ar arguments 667Sends one or more special character sequences to the remote host. 668The following are the arguments which may be specified 669(more than one argument may be specified at a time): 670.Bl -tag -width escape 671.It Ic abort 672Sends the 673.Dv TELNET ABORT 674(Abort 675processes) 676sequence. 677.It Ic ao 678Sends the 679.Dv TELNET AO 680(Abort Output) sequence, which should cause the remote system to flush 681all output 682.Em from 683the remote system 684.Em to 685the user's terminal. 686.It Ic ayt 687Sends the 688.Dv TELNET AYT 689(Are You There) 690sequence, to which the remote system may or may not choose to respond. 691.It Ic brk 692Sends the 693.Dv TELNET BRK 694(Break) sequence, which may have significance to the remote 695system. 696.It Ic ec 697Sends the 698.Dv TELNET EC 699(Erase Character) 700sequence, which should cause the remote system to erase the last character 701entered. 702.It Ic el 703Sends the 704.Dv TELNET EL 705(Erase Line) 706sequence, which should cause the remote system to erase the line currently 707being entered. 708.It Ic eof 709Sends the 710.Dv TELNET EOF 711(End Of File) 712sequence. 713.It Ic eor 714Sends the 715.Dv TELNET EOR 716(End of Record) 717sequence. 718.It Ic escape 719Sends the current 720.Nm 721escape character (initially \*(Lq^\*(Rq). 722.It Ic ga 723Sends the 724.Dv TELNET GA 725(Go Ahead) 726sequence, which likely has no significance to the remote system. 727.It Ic getstatus 728If the remote side supports the 729.Dv TELNET STATUS 730command, 731.Ic getstatus 732will send the subnegotiation to request that the server send 733its current option status. 734.It Ic ip 735Sends the 736.Dv TELNET IP 737(Interrupt Process) sequence, which should cause the remote 738system to abort the currently running process. 739.It Ic nop 740Sends the 741.Dv TELNET NOP 742(No OPeration) 743sequence. 744.It Ic susp 745Sends the 746.Dv TELNET SUSP 747(SUSPend process) 748sequence. 749.It Ic synch 750Sends the 751.Dv TELNET SYNCH 752sequence. 753This sequence causes the remote system to discard all previously typed 754(but not yet read) input. 755This sequence is sent as 756.Tn TCP 757urgent 758data (and may not work if the remote system is a 759.Bx 4.2 760system -- if 761it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal). 762.It Ic do Ar cmd 763.It Ic dont Ar cmd 764.It Ic will Ar cmd 765.It Ic wont Ar cmd 766Sends the 767.Dv TELNET DO 768.Ar cmd 769sequence. 770.Ar Cmd 771can be either a decimal number between 0 and 255, 772or a symbolic name for a specific 773.Dv TELNET 774command. 775.Ar Cmd 776can also be either 777.Ic help 778or 779.Ic ?\& 780to print out help information, including 781a list of known symbolic names. 782.It Ic ?\& 783Prints out help information for the 784.Ic send 785command. 786.El 787.It Ic set Ar argument value 788.It Ic unset Ar argument value 789The 790.Ic set 791command will set any one of a number of 792.Nm 793variables to a specific value or to 794.Dv TRUE . 795The special value 796.Ic off 797turns off the function associated with 798the variable, this is equivalent to using the 799.Ic unset 800command. 801The 802.Ic unset 803command will disable or set to 804.Dv FALSE 805any of the specified functions. 806The values of variables may be interrogated with the 807.Ic display 808command. 809The variables which may be set or unset, but not toggled, are 810listed here. 811In addition, any of the variables for the 812.Ic toggle 813command may be explicitly set or unset using 814the 815.Ic set 816and 817.Ic unset 818commands. 819.Bl -tag -width escape 820.It Ic ayt 821If 822.Tn TELNET 823is in localchars mode, or 824.Dv LINEMODE 825is enabled, and the status character is typed, a 826.Dv TELNET AYT 827sequence (see 828.Ic send ayt 829preceding) is sent to the 830remote host. 831The initial value for the \*(LqAre You There\*(Rq 832character is the terminal's status character. 833.It Ic echo 834This is the value (initially \*(Lq^E\*(Rq) which, when in 835\*(Lqline by line\*(Rq mode, toggles between doing local echoing 836of entered characters (for normal processing), and suppressing 837echoing of entered characters (for entering, say, a password). 838.It Ic eof 839If 840.Nm 841is operating in 842.Dv LINEMODE 843or \*(Lqold line by line\*(Rq mode, entering this character 844as the first character on a line will cause this character to be 845sent to the remote system. 846The initial value of the eof character is taken to be the terminal's 847.Ic eof 848character. 849.It Ic erase 850If 851.Nm 852is in 853.Ic localchars 854mode (see 855.Ic toggle 856.Ic localchars 857below), 858.Sy and 859if 860.Nm 861is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 862character is typed, a 863.Dv TELNET EC 864sequence (see 865.Ic send 866.Ic ec 867above) 868is sent to the remote system. 869The initial value for the erase character is taken to be 870the terminal's 871.Ic erase 872character. 873.It Ic escape 874This is the 875.Nm 876escape character (initially \*(Lq^[\*(Rq) which causes entry 877into 878.Nm 879command mode (when connected to a remote system). 880.It Ic flushoutput 881If 882.Nm 883is in 884.Ic localchars 885mode (see 886.Ic toggle 887.Ic localchars 888below) 889and the 890.Ic flushoutput 891character is typed, a 892.Dv TELNET AO 893sequence (see 894.Ic send 895.Ic ao 896above) 897is sent to the remote host. 898The initial value for the flush character is taken to be 899the terminal's 900.Ic flush 901character. 902.It Ic forw1 903.It Ic forw2 904If 905.Nm 906is operating in 907.Dv LINEMODE , 908these are the 909characters that, when typed, cause partial lines to be 910forwarded to the remote system. 911The initial value for 912the forwarding characters are taken from the terminal's 913eol and eol2 characters. 914.It Ic interrupt 915If 916.Nm 917is in 918.Ic localchars 919mode (see 920.Ic toggle 921.Ic localchars 922below) 923and the 924.Ic interrupt 925character is typed, a 926.Dv TELNET IP 927sequence (see 928.Ic send 929.Ic ip 930above) 931is sent to the remote host. 932The initial value for the interrupt character is taken to be 933the terminal's 934.Ic intr 935character. 936.It Ic kill 937If 938.Nm 939is in 940.Ic localchars 941mode (see 942.Ic toggle 943.Ic localchars 944below), 945.Ic and 946if 947.Nm 948is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 949character is typed, a 950.Dv TELNET EL 951sequence (see 952.Ic send 953.Ic el 954above) 955is sent to the remote system. 956The initial value for the kill character is taken to be 957the terminal's 958.Ic kill 959character. 960.It Ic lnext 961If 962.Nm 963is operating in 964.Dv LINEMODE 965or \*(Lqold line by line\*(Rq mode, then this character is taken to 966be the terminal's 967.Ic lnext 968character. 969The initial value for the lnext character is taken to be 970the terminal's 971.Ic lnext 972character. 973.It Ic quit 974If 975.Nm 976is in 977.Ic localchars 978mode (see 979.Ic toggle 980.Ic localchars 981below) 982and the 983.Ic quit 984character is typed, a 985.Dv TELNET BRK 986sequence (see 987.Ic send 988.Ic brk 989above) 990is sent to the remote host. 991The initial value for the quit character is taken to be 992the terminal's 993.Ic quit 994character. 995.It Ic reprint 996If 997.Nm 998is operating in 999.Dv LINEMODE 1000or \*(Lqold line by line\*(Rq mode, then this character is taken to 1001be the terminal's 1002.Ic reprint 1003character. 1004The initial value for the reprint character is taken to be 1005the terminal's 1006.Ic reprint 1007character. 1008.It Ic rlogin 1009This is the rlogin escape character. 1010If set, the normal 1011.Nm 1012escape character is ignored unless it is 1013preceded by this character at the beginning of a line. 1014This character, at the beginning of a line followed by 1015a "." closes the connection; when followed by a ^Z it 1016suspends the 1017.Nm 1018command. 1019The initial state is to 1020disable the 1021.Nm rlogin 1022escape character. 1023.It Ic start 1024If the 1025.Dv TELNET TOGGLE-FLOW-CONTROL 1026option has been enabled, 1027then this character is taken to 1028be the terminal's 1029.Ic start 1030character. 1031The initial value for the start character is taken to be 1032the terminal's 1033.Ic start 1034character. 1035.It Ic stop 1036If the 1037.Dv TELNET TOGGLE-FLOW-CONTROL 1038option has been enabled, 1039then this character is taken to 1040be the terminal's 1041.Ic stop 1042character. 1043The initial value for the stop character is taken to be 1044the terminal's 1045.Ic stop 1046character. 1047.It Ic susp 1048If 1049.Nm 1050is in 1051.Ic localchars 1052mode, or 1053.Dv LINEMODE 1054is enabled, and the 1055.Ic suspend 1056character is typed, a 1057.Dv TELNET SUSP 1058sequence (see 1059.Ic send 1060.Ic susp 1061above) 1062is sent to the remote host. 1063The initial value for the suspend character is taken to be 1064the terminal's 1065.Ic suspend 1066character. 1067.It Ic tracefile 1068This is the file to which the output, caused by 1069.Ic netdata 1070or 1071.Ic option 1072tracing being 1073.Dv TRUE , 1074will be written. 1075If it is set to 1076.Dq Fl , 1077then tracing information will be written to standard output (the default). 1078.It Ic worderase 1079If 1080.Nm 1081is operating in 1082.Dv LINEMODE 1083or \*(Lqold line by line\*(Rq mode, then this character is taken to 1084be the terminal's 1085.Ic worderase 1086character. 1087The initial value for the worderase character is taken to be 1088the terminal's 1089.Ic worderase 1090character. 1091.It Ic ?\& 1092Displays the legal 1093.Ic set 1094.Pq Ic unset 1095commands. 1096.El 1097.It Ic opie Ar sequence challenge 1098The 1099.Ic opie 1100command computes a response to the OPIE challenge. 1101.It Ic slc Ar state 1102The 1103.Ic slc 1104command (Set Local Characters) is used to set 1105or change the state of the special 1106characters when the 1107.Dv TELNET LINEMODE 1108option has 1109been enabled. 1110Special characters are characters that get 1111mapped to 1112.Tn TELNET 1113commands sequences (like 1114.Ic ip 1115or 1116.Ic quit ) 1117or line editing characters (like 1118.Ic erase 1119and 1120.Ic kill ) . 1121By default, the local special characters are exported. 1122.Bl -tag -width Fl 1123.It Ic check 1124Verify the current settings for the current special characters. 1125The remote side is requested to send all the current special 1126character settings, and if there are any discrepancies with 1127the local side, the local side will switch to the remote value. 1128.It Ic export 1129Switch to the local defaults for the special characters. 1130The 1131local default characters are those of the local terminal at 1132the time when 1133.Nm 1134was started. 1135.It Ic import 1136Switch to the remote defaults for the special characters. 1137The remote default characters are those of the remote system 1138at the time when the 1139.Tn TELNET 1140connection was established. 1141.It Ic ?\& 1142Prints out help information for the 1143.Ic slc 1144command. 1145.El 1146.It Ic status 1147Show the current status of 1148.Nm . 1149This includes the peer one is connected to, as well 1150as the current mode. 1151.It Ic toggle Ar arguments ... 1152Toggle (between 1153.Dv TRUE 1154and 1155.Dv FALSE ) 1156various flags that control how 1157.Nm 1158responds to events. 1159These flags may be set explicitly to 1160.Dv TRUE 1161or 1162.Dv FALSE 1163using the 1164.Ic set 1165and 1166.Ic unset 1167commands listed above. 1168More than one argument may be specified. 1169The state of these flags may be interrogated with the 1170.Ic display 1171command. 1172Valid arguments are: 1173.Bl -tag -width Ar 1174.It Ic authdebug 1175Turns on debugging information for the authentication code. 1176.It Ic autoflush 1177If 1178.Ic autoflush 1179and 1180.Ic localchars 1181are both 1182.Dv TRUE , 1183then when the 1184.Ic ao , 1185or 1186.Ic quit 1187characters are recognized (and transformed into 1188.Tn TELNET 1189sequences; see 1190.Ic set 1191above for details), 1192.Nm 1193refuses to display any data on the user's terminal 1194until the remote system acknowledges (via a 1195.Dv TELNET TIMING MARK 1196option) 1197that it has processed those 1198.Tn TELNET 1199sequences. 1200The initial value for this toggle is 1201.Dv TRUE 1202if the terminal user had not 1203done an "stty noflsh", otherwise 1204.Dv FALSE 1205(see 1206.Xr stty 1 ) . 1207.It Ic autodecrypt 1208When the 1209.Dv TELNET ENCRYPT 1210option is negotiated, by 1211default the actual encryption (decryption) of the data 1212stream does not start automatically. 1213The autoencrypt 1214(autodecrypt) command states that encryption of the 1215output (input) stream should be enabled as soon as 1216possible. 1217.It Ic autologin 1218If the remote side supports the 1219.Dv TELNET AUTHENTICATION 1220option 1221.Nm 1222attempts to use it to perform automatic authentication. 1223If the 1224.Dv AUTHENTICATION 1225option is not supported, the user's login 1226name are propagated through the 1227.Dv TELNET ENVIRON 1228option. 1229This command is the same as specifying 1230.Fl a 1231option on the 1232.Ic open 1233command. 1234.It Ic autosynch 1235If 1236.Ic autosynch 1237and 1238.Ic localchars 1239are both 1240.Dv TRUE , 1241then when either the 1242.Ic intr 1243or 1244.Ic quit 1245characters is typed (see 1246.Ic set 1247above for descriptions of the 1248.Ic intr 1249and 1250.Ic quit 1251characters), the resulting 1252.Tn TELNET 1253sequence sent is followed by the 1254.Dv TELNET SYNCH 1255sequence. 1256This procedure 1257.Ic should 1258cause the remote system to begin throwing away all previously 1259typed input until both of the 1260.Tn TELNET 1261sequences have been read and acted upon. 1262The initial value of this toggle is 1263.Dv FALSE . 1264.It Ic binary 1265Enable or disable the 1266.Dv TELNET BINARY 1267option on both input and output. 1268.It Ic inbinary 1269Enable or disable the 1270.Dv TELNET BINARY 1271option on input. 1272.It Ic outbinary 1273Enable or disable the 1274.Dv TELNET BINARY 1275option on output. 1276.It Ic crlf 1277If this is 1278.Dv TRUE , 1279then carriage returns will be sent as 1280.Li <CR><LF> . 1281If this is 1282.Dv FALSE , 1283then carriage returns will be send as 1284.Li <CR><NUL> . 1285The initial value for this toggle is 1286.Dv FALSE . 1287.It Ic crmod 1288Toggle carriage return mode. 1289When this mode is enabled, most carriage return characters received from 1290the remote host will be mapped into a carriage return followed by 1291a line feed. 1292This mode does not affect those characters typed by the user, only 1293those received from the remote host. 1294This mode is not very useful unless the remote host 1295only sends carriage return, but never line feed. 1296The initial value for this toggle is 1297.Dv FALSE . 1298.It Ic debug 1299Toggles socket level debugging (useful only to the 1300.Ic super user ) . 1301The initial value for this toggle is 1302.Dv FALSE . 1303.It Ic encdebug 1304Turns on debugging information for the encryption code. 1305.It Ic localchars 1306If this is 1307.Dv TRUE , 1308then the 1309.Ic flush , 1310.Ic interrupt , 1311.Ic quit , 1312.Ic erase , 1313and 1314.Ic kill 1315characters (see 1316.Ic set 1317above) are recognized locally, and transformed into (hopefully) appropriate 1318.Tn TELNET 1319control sequences 1320(respectively 1321.Ic ao , 1322.Ic ip , 1323.Ic brk , 1324.Ic ec , 1325and 1326.Ic el ; 1327see 1328.Ic send 1329above). 1330The initial value for this toggle is 1331.Dv TRUE 1332in \*(Lqold line by line\*(Rq mode, 1333and 1334.Dv FALSE 1335in \*(Lqcharacter at a time\*(Rq mode. 1336When the 1337.Dv LINEMODE 1338option is enabled, the value of 1339.Ic localchars 1340is ignored, and assumed to always be 1341.Dv TRUE . 1342If 1343.Dv LINEMODE 1344has ever been enabled, then 1345.Ic quit 1346is sent as 1347.Ic abort , 1348and 1349.Ic eof 1350and 1351.Ic suspend 1352are sent as 1353.Ic eof 1354and 1355.Ic susp 1356(see 1357.Ic send 1358above). 1359.It Ic netdata 1360Toggles the display of all network data (in hexadecimal format). 1361The initial value for this toggle is 1362.Dv FALSE . 1363.It Ic options 1364Toggles the display of some internal 1365.Nm 1366protocol processing (having to do with 1367.Tn TELNET 1368options). 1369The initial value for this toggle is 1370.Dv FALSE . 1371.It Ic prettydump 1372When the 1373.Ic netdata 1374toggle is enabled, if 1375.Ic prettydump 1376is enabled the output from the 1377.Ic netdata 1378command will be formatted in a more user readable format. 1379Spaces are put between each character in the output, and the 1380beginning of any 1381.Nm 1382escape sequence is preceded by a '*' to aid in locating them. 1383.It Ic skiprc 1384When the skiprc toggle is 1385.Dv TRUE , 1386.Nm 1387skips the reading of the 1388.Pa \&.telnetrc 1389file in the users home 1390directory when connections are opened. 1391The initial 1392value for this toggle is 1393.Dv FALSE . 1394.It Ic termdata 1395Toggles the display of all terminal data (in hexadecimal format). 1396The initial value for this toggle is 1397.Dv FALSE . 1398.It Ic verbose_encrypt 1399When the 1400.Ic verbose_encrypt 1401toggle is 1402.Dv TRUE , 1403.Nm 1404prints out a message each time encryption is enabled or 1405disabled. 1406The initial value for this toggle is 1407.Dv FALSE . 1408.It Ic ?\& 1409Displays the legal 1410.Ic toggle 1411commands. 1412.El 1413.It Ic z 1414Suspend 1415.Nm . 1416This command only works when the user is using the 1417.Xr csh 1 . 1418.It Ic \&! Op Ar command 1419Execute a single command in a subshell on the local 1420system. 1421If 1422.Ar command 1423is omitted, then an interactive 1424subshell is invoked. 1425.It Ic ?\& Op Ar command 1426Get help. 1427With no arguments, 1428.Nm 1429prints a help summary. 1430If 1431.Ar command 1432is specified, 1433.Nm 1434will print the help information for just that command. 1435.El 1436.Sh ENVIRONMENT 1437.Nm 1438uses at least the 1439.Ev HOME , 1440.Ev SHELL , 1441.Ev DISPLAY , 1442and 1443.Ev TERM 1444environment variables. 1445Other environment variables may be propagated 1446to the other side via the 1447.Dv TELNET ENVIRON 1448option. 1449.Sh FILES 1450.Bl -tag -width ~/.telnetrc -compact 1451.It Pa ~/.telnetrc 1452user customized telnet startup values 1453.El 1454.Sh SEE ALSO 1455.Xr rlogin 1 , 1456.Xr rsh 1 , 1457.Xr hosts 5 , 1458.Xr nologin 5 , 1459.Xr telnetd 8 1460.Sh HISTORY 1461The 1462.Nm 1463command appeared in 1464.Bx 4.2 . 1465.Pp 1466IPv6 support was added by WIDE/KAME project. 1467.Sh NOTES 1468On some remote systems, echo has to be turned off manually when in 1469\*(Lqold line by line\*(Rq mode. 1470.Pp 1471In \*(Lqold line by line\*(Rq mode or 1472.Dv LINEMODE 1473the terminal's 1474.Ic eof 1475character is only recognized (and sent to the remote system) 1476when it is the first character on a line. 1477