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.\" $FreeBSD$ 30.\" 31.Dd September 18, 2006 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 B Ar baudrate 43.Op Fl S Ar tos 44.Op Fl X Ar authtype 45.Op Fl e Ar escapechar 46.Op Fl k Ar realm 47.Op Fl l Ar user 48.Op Fl n Ar tracefile 49.Op Fl s Ar src_addr 50.Oo 51.Ar host 52.Op Ar port 53.Oc 54.Sh DESCRIPTION 55The 56.Nm 57command 58is used to communicate with another host using the 59.Tn TELNET 60protocol. 61If 62.Nm 63is invoked without the 64.Ar host 65argument, it enters command mode, 66indicated by its prompt 67.Pq Dq Li telnet\&> . 68In this mode, it accepts and executes the commands listed below. 69If it is invoked with arguments, it performs an 70.Ic open 71command with those arguments. 72.Pp 73Options: 74.Bl -tag -width indent 75.It Fl 4 76Forces 77.Nm 78to use IPv4 addresses only. 79.It Fl 6 80Forces 81.Nm 82to use IPv6 addresses only. 83.It Fl 8 84Specifies an 8-bit data path. 85This causes an attempt to 86negotiate the 87.Dv TELNET BINARY 88option on both input and output. 89.It Fl B Ar baudrate 90Sets the baud rate to 91.Ar baudrate . 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.Bl -tag -width "mode type" 348.It Ic auth Ar argument ... 349The auth command manipulates the information sent through the 350.Dv TELNET AUTHENTICATE 351option. 352Valid arguments for the 353.Ic auth 354command are: 355.Bl -tag -width "disable type" 356.It Ic disable Ar type 357Disables the specified type of authentication. 358To 359obtain a list of available types, use the 360.Ic auth disable ?\& 361command. 362.It Ic enable Ar type 363Enables the specified type of authentication. 364To 365obtain a list of available types, use the 366.Ic auth enable ?\& 367command. 368.It Ic status 369Lists the current status of the various types of 370authentication. 371.El 372.It Ic close 373Close a 374.Tn TELNET 375session and return to command mode. 376.It Ic display Ar argument ... 377Displays all, or some, of the 378.Ic set 379and 380.Ic toggle 381values (see below). 382.It Ic encrypt Ar argument ... 383The encrypt command manipulates the information sent through the 384.Dv TELNET ENCRYPT 385option. 386.Pp 387Valid arguments for the 388.Ic encrypt 389command are: 390.Bl -tag -width Ar 391.It Ic disable Ar type Xo 392.Op Cm input | output 393.Xc 394Disables the specified type of encryption. 395If you 396omit the input and output, both input and output 397are disabled. 398To obtain a list of available 399types, use the 400.Ic encrypt disable ?\& 401command. 402.It Ic enable Ar type Xo 403.Op Cm input | output 404.Xc 405Enables the specified type of encryption. 406If you 407omit input and output, both input and output are 408enabled. 409To obtain a list of available types, use the 410.Ic encrypt enable ?\& 411command. 412.It Ic input 413This is the same as the 414.Ic encrypt start input 415command. 416.It Ic -input 417This is the same as the 418.Ic encrypt stop input 419command. 420.It Ic output 421This is the same as the 422.Ic encrypt start output 423command. 424.It Ic -output 425This is the same as the 426.Ic encrypt stop output 427command. 428.It Ic start Op Cm input | output 429Attempts to start encryption. 430If you omit 431.Ic input 432and 433.Ic output , 434both input and output are enabled. 435To 436obtain a list of available types, use the 437.Ic encrypt enable ?\& 438command. 439.It Ic status 440Lists the current status of encryption. 441.It Ic stop Op Cm input | output 442Stops encryption. 443If you omit input and output, 444encryption is on both input and output. 445.It Ic type Ar type 446Sets the default type of encryption to be used 447with later 448.Ic encrypt start 449or 450.Ic encrypt stop 451commands. 452.El 453.It Ic environ Ar arguments ... 454The 455.Ic environ 456command is used to manipulate the 457variables that may be sent through the 458.Dv TELNET ENVIRON 459option. 460The initial set of variables is taken from the users 461environment, with only the 462.Ev DISPLAY 463and 464.Ev PRINTER 465variables being exported by default. 466The 467.Ev USER 468variable is also exported if the 469.Fl a 470or 471.Fl l 472options are used. 473.Pp 474Valid arguments for the 475.Ic environ 476command are: 477.Bl -tag -width Fl 478.It Ic define Ar variable value 479Define the variable 480.Ar variable 481to have a value of 482.Ar value . 483Any variables defined by this command are automatically exported. 484The 485.Ar value 486may be enclosed in single or double quotes so 487that tabs and spaces may be included. 488.It Ic undefine Ar variable 489Remove 490.Ar variable 491from the list of environment variables. 492.It Ic export Ar variable 493Mark the variable 494.Ar variable 495to be exported to the remote side. 496.It Ic unexport Ar variable 497Mark the variable 498.Ar variable 499to not be exported unless 500explicitly asked for by the remote side. 501.It Ic list 502List the current set of environment variables. 503Those marked with a 504.Cm * 505will be sent automatically, 506other variables will only be sent if explicitly requested. 507.It Ic ?\& 508Prints out help information for the 509.Ic environ 510command. 511.El 512.It Ic logout 513Sends the 514.Dv TELNET LOGOUT 515option to the remote side. 516This command is similar to a 517.Ic close 518command; however, if the remote side does not support the 519.Dv LOGOUT 520option, nothing happens. 521If, however, the remote side does support the 522.Dv LOGOUT 523option, this command should cause the remote side to close the 524.Tn TELNET 525connection. 526If the remote side also supports the concept of 527suspending a user's session for later reattachment, 528the logout argument indicates that you 529should terminate the session immediately. 530.It Ic mode Ar type 531.Ar Type 532is one of several options, depending on the state of the 533.Tn TELNET 534session. 535The remote host is asked for permission to go into the requested mode. 536If the remote host is capable of entering that mode, the requested 537mode will be entered. 538.Bl -tag -width Ar 539.It Ic character 540Disable the 541.Dv TELNET LINEMODE 542option, or, if the remote side does not understand the 543.Dv LINEMODE 544option, then enter \*(Lqcharacter at a time\*(Rq mode. 545.It Ic line 546Enable the 547.Dv TELNET LINEMODE 548option, or, if the remote side does not understand the 549.Dv LINEMODE 550option, then attempt to enter \*(Lqold-line-by-line\*(Rq mode. 551.It Ic isig Pq Ic \-isig 552Attempt to enable (disable) the 553.Dv TRAPSIG 554mode of the 555.Dv LINEMODE 556option. 557This requires that the 558.Dv LINEMODE 559option be enabled. 560.It Ic edit Pq Ic \-edit 561Attempt to enable (disable) the 562.Dv EDIT 563mode of the 564.Dv LINEMODE 565option. 566This requires that the 567.Dv LINEMODE 568option be enabled. 569.It Ic softtabs Pq Ic \-softtabs 570Attempt to enable (disable) the 571.Dv SOFT_TAB 572mode of the 573.Dv LINEMODE 574option. 575This requires that the 576.Dv LINEMODE 577option be enabled. 578.It Ic litecho Pq Ic \-litecho 579Attempt to enable (disable) the 580.Dv LIT_ECHO 581mode of the 582.Dv LINEMODE 583option. 584This requires that the 585.Dv LINEMODE 586option be enabled. 587.It Ic ?\& 588Prints out help information for the 589.Ic mode 590command. 591.El 592.It Xo 593.Ic open 594.Op Fl l Ar user 595.Op Ar host 596.Op Oo Fl /+ Oc Ns Ar port 597.Xc 598Open a connection to the named host. 599If no port number 600is specified, 601.Nm 602will attempt to contact a 603.Tn TELNET 604server at the default port. 605The host specification may be either a host name (see 606.Xr hosts 5 ) , 607an Internet address specified in the \*(Lqdot notation\*(Rq (see 608.Xr inet 3 ) , 609or IPv6 host name or IPv6 coloned-hexadecimal addreess. 610The 611.Fl l 612option may be used to specify the user name 613to be passed to the remote system via the 614.Ev ENVIRON 615option. 616When connecting to a non-standard port, 617.Nm 618omits any automatic initiation of 619.Tn TELNET 620options. 621When the port number is preceded by a minus sign, 622the initial option negotiation is done. 623When, however, the port number 624is preceded by a plus sign, 625any option negotiation and understanding is prohibited, 626making telnet dumb client for POP3/SMTP/NNTP/HTTP-like 627protocols with any data including 628.Tn TELNET 629IAC character (0xff). 630After establishing a connection, the file 631.Pa \&.telnetrc 632in the 633users home directory is opened. 634Lines beginning with a # are 635comment lines. 636Blank lines are ignored. 637Lines that begin 638without white space are the start of a machine entry. 639The 640first thing on the line is the name of the machine that is 641being connected to. 642It may be the hostname or numeric address specified as the argument 643.Ar host , 644the canonical name of that string as determined by 645.Xr getaddrinfo 3 , 646or the string 647.Dq Li DEFAULT 648indicating all hosts. 649The rest of the line, and successive 650lines that begin with white space are assumed to be 651.Nm 652commands and are processed as if they had been typed 653in manually to the 654.Nm 655command prompt. 656.It Ic quit 657Close any open 658.Tn TELNET 659session and exit 660.Nm . 661An end of file (in command mode) will also close a session and exit. 662.It Ic send Ar arguments 663Sends one or more special character sequences to the remote host. 664The following are the arguments which may be specified 665(more than one argument may be specified at a time): 666.Bl -tag -width escape 667.It Ic abort 668Sends the 669.Dv TELNET ABORT 670(Abort 671processes) 672sequence. 673.It Ic ao 674Sends the 675.Dv TELNET AO 676(Abort Output) sequence, which should cause the remote system to flush 677all output 678.Em from 679the remote system 680.Em to 681the user's terminal. 682.It Ic ayt 683Sends the 684.Dv TELNET AYT 685(Are You There) 686sequence, to which the remote system may or may not choose to respond. 687.It Ic brk 688Sends the 689.Dv TELNET BRK 690(Break) sequence, which may have significance to the remote 691system. 692.It Ic ec 693Sends the 694.Dv TELNET EC 695(Erase Character) 696sequence, which should cause the remote system to erase the last character 697entered. 698.It Ic el 699Sends the 700.Dv TELNET EL 701(Erase Line) 702sequence, which should cause the remote system to erase the line currently 703being entered. 704.It Ic eof 705Sends the 706.Dv TELNET EOF 707(End Of File) 708sequence. 709.It Ic eor 710Sends the 711.Dv TELNET EOR 712(End of Record) 713sequence. 714.It Ic escape 715Sends the current 716.Nm 717escape character (initially \*(Lq^\*(Rq). 718.It Ic ga 719Sends the 720.Dv TELNET GA 721(Go Ahead) 722sequence, which likely has no significance to the remote system. 723.It Ic getstatus 724If the remote side supports the 725.Dv TELNET STATUS 726command, 727.Ic getstatus 728will send the subnegotiation to request that the server send 729its current option status. 730.It Ic ip 731Sends the 732.Dv TELNET IP 733(Interrupt Process) sequence, which should cause the remote 734system to abort the currently running process. 735.It Ic nop 736Sends the 737.Dv TELNET NOP 738(No OPeration) 739sequence. 740.It Ic susp 741Sends the 742.Dv TELNET SUSP 743(SUSPend process) 744sequence. 745.It Ic synch 746Sends the 747.Dv TELNET SYNCH 748sequence. 749This sequence causes the remote system to discard all previously typed 750(but not yet read) input. 751This sequence is sent as 752.Tn TCP 753urgent 754data (and may not work if the remote system is a 755.Bx 4.2 756system -- if 757it doesn't work, a lower case \*(Lqr\*(Rq may be echoed on the terminal). 758.It Ic do Ar cmd 759.It Ic dont Ar cmd 760.It Ic will Ar cmd 761.It Ic wont Ar cmd 762Sends the 763.Dv TELNET DO 764.Ar cmd 765sequence. 766.Ar Cmd 767can be either a decimal number between 0 and 255, 768or a symbolic name for a specific 769.Dv TELNET 770command. 771.Ar Cmd 772can also be either 773.Ic help 774or 775.Ic ?\& 776to print out help information, including 777a list of known symbolic names. 778.It Ic ?\& 779Prints out help information for the 780.Ic send 781command. 782.El 783.It Ic set Ar argument value 784.It Ic unset Ar argument value 785The 786.Ic set 787command will set any one of a number of 788.Nm 789variables to a specific value or to 790.Dv TRUE . 791The special value 792.Ic off 793turns off the function associated with 794the variable, this is equivalent to using the 795.Ic unset 796command. 797The 798.Ic unset 799command will disable or set to 800.Dv FALSE 801any of the specified functions. 802The values of variables may be interrogated with the 803.Ic display 804command. 805The variables which may be set or unset, but not toggled, are 806listed here. 807In addition, any of the variables for the 808.Ic toggle 809command may be explicitly set or unset using 810the 811.Ic set 812and 813.Ic unset 814commands. 815.Bl -tag -width escape 816.It Ic ayt 817If 818.Tn TELNET 819is in localchars mode, or 820.Dv LINEMODE 821is enabled, and the status character is typed, a 822.Dv TELNET AYT 823sequence (see 824.Ic send ayt 825preceding) is sent to the 826remote host. 827The initial value for the \*(LqAre You There\*(Rq 828character is the terminal's status character. 829.It Ic echo 830This is the value (initially \*(Lq^E\*(Rq) which, when in 831\*(Lqline by line\*(Rq mode, toggles between doing local echoing 832of entered characters (for normal processing), and suppressing 833echoing of entered characters (for entering, say, a password). 834.It Ic eof 835If 836.Nm 837is operating in 838.Dv LINEMODE 839or \*(Lqold line by line\*(Rq mode, entering this character 840as the first character on a line will cause this character to be 841sent to the remote system. 842The initial value of the eof character is taken to be the terminal's 843.Ic eof 844character. 845.It Ic erase 846If 847.Nm 848is in 849.Ic localchars 850mode (see 851.Ic toggle 852.Ic localchars 853below), 854.Sy and 855if 856.Nm 857is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 858character is typed, a 859.Dv TELNET EC 860sequence (see 861.Ic send 862.Ic ec 863above) 864is sent to the remote system. 865The initial value for the erase character is taken to be 866the terminal's 867.Ic erase 868character. 869.It Ic escape 870This is the 871.Nm 872escape character (initially \*(Lq^[\*(Rq) which causes entry 873into 874.Nm 875command mode (when connected to a remote system). 876.It Ic flushoutput 877If 878.Nm 879is in 880.Ic localchars 881mode (see 882.Ic toggle 883.Ic localchars 884below) 885and the 886.Ic flushoutput 887character is typed, a 888.Dv TELNET AO 889sequence (see 890.Ic send 891.Ic ao 892above) 893is sent to the remote host. 894The initial value for the flush character is taken to be 895the terminal's 896.Ic flush 897character. 898.It Ic forw1 899.It Ic forw2 900If 901.Nm 902is operating in 903.Dv LINEMODE , 904these are the 905characters that, when typed, cause partial lines to be 906forwarded to the remote system. 907The initial value for 908the forwarding characters are taken from the terminal's 909eol and eol2 characters. 910.It Ic interrupt 911If 912.Nm 913is in 914.Ic localchars 915mode (see 916.Ic toggle 917.Ic localchars 918below) 919and the 920.Ic interrupt 921character is typed, a 922.Dv TELNET IP 923sequence (see 924.Ic send 925.Ic ip 926above) 927is sent to the remote host. 928The initial value for the interrupt character is taken to be 929the terminal's 930.Ic intr 931character. 932.It Ic kill 933If 934.Nm 935is in 936.Ic localchars 937mode (see 938.Ic toggle 939.Ic localchars 940below), 941.Ic and 942if 943.Nm 944is operating in \*(Lqcharacter at a time\*(Rq mode, then when this 945character is typed, a 946.Dv TELNET EL 947sequence (see 948.Ic send 949.Ic el 950above) 951is sent to the remote system. 952The initial value for the kill character is taken to be 953the terminal's 954.Ic kill 955character. 956.It Ic lnext 957If 958.Nm 959is operating in 960.Dv LINEMODE 961or \*(Lqold line by line\*(Rq mode, then this character is taken to 962be the terminal's 963.Ic lnext 964character. 965The initial value for the lnext character is taken to be 966the terminal's 967.Ic lnext 968character. 969.It Ic quit 970If 971.Nm 972is in 973.Ic localchars 974mode (see 975.Ic toggle 976.Ic localchars 977below) 978and the 979.Ic quit 980character is typed, a 981.Dv TELNET BRK 982sequence (see 983.Ic send 984.Ic brk 985above) 986is sent to the remote host. 987The initial value for the quit character is taken to be 988the terminal's 989.Ic quit 990character. 991.It Ic reprint 992If 993.Nm 994is operating in 995.Dv LINEMODE 996or \*(Lqold line by line\*(Rq mode, then this character is taken to 997be the terminal's 998.Ic reprint 999character. 1000The initial value for the reprint character is taken to be 1001the terminal's 1002.Ic reprint 1003character. 1004.It Ic rlogin 1005This is the rlogin escape character. 1006If set, the normal 1007.Nm 1008escape character is ignored unless it is 1009preceded by this character at the beginning of a line. 1010This character, at the beginning of a line followed by 1011a "." closes the connection; when followed by a ^Z it 1012suspends the 1013.Nm 1014command. 1015The initial state is to 1016disable the 1017.Nm rlogin 1018escape character. 1019.It Ic start 1020If the 1021.Dv TELNET TOGGLE-FLOW-CONTROL 1022option has been enabled, 1023then this character is taken to 1024be the terminal's 1025.Ic start 1026character. 1027The initial value for the start character is taken to be 1028the terminal's 1029.Ic start 1030character. 1031.It Ic stop 1032If the 1033.Dv TELNET TOGGLE-FLOW-CONTROL 1034option has been enabled, 1035then this character is taken to 1036be the terminal's 1037.Ic stop 1038character. 1039The initial value for the stop character is taken to be 1040the terminal's 1041.Ic stop 1042character. 1043.It Ic susp 1044If 1045.Nm 1046is in 1047.Ic localchars 1048mode, or 1049.Dv LINEMODE 1050is enabled, and the 1051.Ic suspend 1052character is typed, a 1053.Dv TELNET SUSP 1054sequence (see 1055.Ic send 1056.Ic susp 1057above) 1058is sent to the remote host. 1059The initial value for the suspend character is taken to be 1060the terminal's 1061.Ic suspend 1062character. 1063.It Ic tracefile 1064This is the file to which the output, caused by 1065.Ic netdata 1066or 1067.Ic option 1068tracing being 1069.Dv TRUE , 1070will be written. 1071If it is set to 1072.Dq Fl , 1073then tracing information will be written to standard output (the default). 1074.It Ic worderase 1075If 1076.Nm 1077is operating in 1078.Dv LINEMODE 1079or \*(Lqold line by line\*(Rq mode, then this character is taken to 1080be the terminal's 1081.Ic worderase 1082character. 1083The initial value for the worderase character is taken to be 1084the terminal's 1085.Ic worderase 1086character. 1087.It Ic ?\& 1088Displays the legal 1089.Ic set 1090.Pq Ic unset 1091commands. 1092.El 1093.It Ic opie Ar sequence challenge 1094The 1095.Ic opie 1096command computes a response to the OPIE challenge. 1097.It Ic slc Ar state 1098The 1099.Ic slc 1100command (Set Local Characters) is used to set 1101or change the state of the special 1102characters when the 1103.Dv TELNET LINEMODE 1104option has 1105been enabled. 1106Special characters are characters that get 1107mapped to 1108.Tn TELNET 1109commands sequences (like 1110.Ic ip 1111or 1112.Ic quit ) 1113or line editing characters (like 1114.Ic erase 1115and 1116.Ic kill ) . 1117By default, the local special characters are exported. 1118.Bl -tag -width Fl 1119.It Ic check 1120Verify the current settings for the current special characters. 1121The remote side is requested to send all the current special 1122character settings, and if there are any discrepancies with 1123the local side, the local side will switch to the remote value. 1124.It Ic export 1125Switch to the local defaults for the special characters. 1126The 1127local default characters are those of the local terminal at 1128the time when 1129.Nm 1130was started. 1131.It Ic import 1132Switch to the remote defaults for the special characters. 1133The remote default characters are those of the remote system 1134at the time when the 1135.Tn TELNET 1136connection was established. 1137.It Ic ?\& 1138Prints out help information for the 1139.Ic slc 1140command. 1141.El 1142.It Ic status 1143Show the current status of 1144.Nm . 1145This includes the peer one is connected to, as well 1146as the current mode. 1147.It Ic toggle Ar arguments ... 1148Toggle (between 1149.Dv TRUE 1150and 1151.Dv FALSE ) 1152various flags that control how 1153.Nm 1154responds to events. 1155These flags may be set explicitly to 1156.Dv TRUE 1157or 1158.Dv FALSE 1159using the 1160.Ic set 1161and 1162.Ic unset 1163commands listed above. 1164More than one argument may be specified. 1165The state of these flags may be interrogated with the 1166.Ic display 1167command. 1168Valid arguments are: 1169.Bl -tag -width Ar 1170.It Ic authdebug 1171Turns on debugging information for the authentication code. 1172.It Ic autoflush 1173If 1174.Ic autoflush 1175and 1176.Ic localchars 1177are both 1178.Dv TRUE , 1179then when the 1180.Ic ao , 1181or 1182.Ic quit 1183characters are recognized (and transformed into 1184.Tn TELNET 1185sequences; see 1186.Ic set 1187above for details), 1188.Nm 1189refuses to display any data on the user's terminal 1190until the remote system acknowledges (via a 1191.Dv TELNET TIMING MARK 1192option) 1193that it has processed those 1194.Tn TELNET 1195sequences. 1196The initial value for this toggle is 1197.Dv TRUE 1198if the terminal user had not 1199done an "stty noflsh", otherwise 1200.Dv FALSE 1201(see 1202.Xr stty 1 ) . 1203.It Ic autodecrypt 1204When the 1205.Dv TELNET ENCRYPT 1206option is negotiated, by 1207default the actual encryption (decryption) of the data 1208stream does not start automatically. 1209The autoencrypt 1210(autodecrypt) command states that encryption of the 1211output (input) stream should be enabled as soon as 1212possible. 1213.It Ic autologin 1214If the remote side supports the 1215.Dv TELNET AUTHENTICATION 1216option 1217.Nm 1218attempts to use it to perform automatic authentication. 1219If the 1220.Dv AUTHENTICATION 1221option is not supported, the user's login 1222name are propagated through the 1223.Dv TELNET ENVIRON 1224option. 1225This command is the same as specifying 1226.Fl a 1227option on the 1228.Ic open 1229command. 1230.It Ic autosynch 1231If 1232.Ic autosynch 1233and 1234.Ic localchars 1235are both 1236.Dv TRUE , 1237then when either the 1238.Ic intr 1239or 1240.Ic quit 1241characters is typed (see 1242.Ic set 1243above for descriptions of the 1244.Ic intr 1245and 1246.Ic quit 1247characters), the resulting 1248.Tn TELNET 1249sequence sent is followed by the 1250.Dv TELNET SYNCH 1251sequence. 1252This procedure 1253.Ic should 1254cause the remote system to begin throwing away all previously 1255typed input until both of the 1256.Tn TELNET 1257sequences have been read and acted upon. 1258The initial value of this toggle is 1259.Dv FALSE . 1260.It Ic binary 1261Enable or disable the 1262.Dv TELNET BINARY 1263option on both input and output. 1264.It Ic inbinary 1265Enable or disable the 1266.Dv TELNET BINARY 1267option on input. 1268.It Ic outbinary 1269Enable or disable the 1270.Dv TELNET BINARY 1271option on output. 1272.It Ic crlf 1273If this is 1274.Dv TRUE , 1275then carriage returns will be sent as 1276.Li <CR><LF> . 1277If this is 1278.Dv FALSE , 1279then carriage returns will be send as 1280.Li <CR><NUL> . 1281The initial value for this toggle is 1282.Dv FALSE . 1283.It Ic crmod 1284Toggle carriage return mode. 1285When this mode is enabled, most carriage return characters received from 1286the remote host will be mapped into a carriage return followed by 1287a line feed. 1288This mode does not affect those characters typed by the user, only 1289those received from the remote host. 1290This mode is not very useful unless the remote host 1291only sends carriage return, but never line feed. 1292The initial value for this toggle is 1293.Dv FALSE . 1294.It Ic debug 1295Toggles socket level debugging (useful only to the 1296.Ic super user ) . 1297The initial value for this toggle is 1298.Dv FALSE . 1299.It Ic encdebug 1300Turns on debugging information for the encryption code. 1301.It Ic localchars 1302If this is 1303.Dv TRUE , 1304then the 1305.Ic flush , 1306.Ic interrupt , 1307.Ic quit , 1308.Ic erase , 1309and 1310.Ic kill 1311characters (see 1312.Ic set 1313above) are recognized locally, and transformed into (hopefully) appropriate 1314.Tn TELNET 1315control sequences 1316(respectively 1317.Ic ao , 1318.Ic ip , 1319.Ic brk , 1320.Ic ec , 1321and 1322.Ic el ; 1323see 1324.Ic send 1325above). 1326The initial value for this toggle is 1327.Dv TRUE 1328in \*(Lqold line by line\*(Rq mode, 1329and 1330.Dv FALSE 1331in \*(Lqcharacter at a time\*(Rq mode. 1332When the 1333.Dv LINEMODE 1334option is enabled, the value of 1335.Ic localchars 1336is ignored, and assumed to always be 1337.Dv TRUE . 1338If 1339.Dv LINEMODE 1340has ever been enabled, then 1341.Ic quit 1342is sent as 1343.Ic abort , 1344and 1345.Ic eof 1346and 1347.Ic suspend 1348are sent as 1349.Ic eof 1350and 1351.Ic susp 1352(see 1353.Ic send 1354above). 1355.It Ic netdata 1356Toggles the display of all network data (in hexadecimal format). 1357The initial value for this toggle is 1358.Dv FALSE . 1359.It Ic options 1360Toggles the display of some internal 1361.Nm 1362protocol processing (having to do with 1363.Tn TELNET 1364options). 1365The initial value for this toggle is 1366.Dv FALSE . 1367.It Ic prettydump 1368When the 1369.Ic netdata 1370toggle is enabled, if 1371.Ic prettydump 1372is enabled the output from the 1373.Ic netdata 1374command will be formatted in a more user readable format. 1375Spaces are put between each character in the output, and the 1376beginning of any 1377.Nm 1378escape sequence is preceded by a '*' to aid in locating them. 1379.It Ic skiprc 1380When the skiprc toggle is 1381.Dv TRUE , 1382.Nm 1383skips the reading of the 1384.Pa \&.telnetrc 1385file in the users home 1386directory when connections are opened. 1387The initial 1388value for this toggle is 1389.Dv FALSE . 1390.It Ic termdata 1391Toggles the display of all terminal data (in hexadecimal format). 1392The initial value for this toggle is 1393.Dv FALSE . 1394.It Ic verbose_encrypt 1395When the 1396.Ic verbose_encrypt 1397toggle is 1398.Dv TRUE , 1399.Nm 1400prints out a message each time encryption is enabled or 1401disabled. 1402The initial value for this toggle is 1403.Dv FALSE . 1404.It Ic ?\& 1405Displays the legal 1406.Ic toggle 1407commands. 1408.El 1409.It Ic z 1410Suspend 1411.Nm . 1412This command only works when the user is using the 1413.Xr csh 1 . 1414.It Ic \&! Op Ar command 1415Execute a single command in a subshell on the local 1416system. 1417If 1418.Ar command 1419is omitted, then an interactive 1420subshell is invoked. 1421.It Ic ?\& Op Ar command 1422Get help. 1423With no arguments, 1424.Nm 1425prints a help summary. 1426If 1427.Ar command 1428is specified, 1429.Nm 1430will print the help information for just that command. 1431.El 1432.Sh ENVIRONMENT 1433.Nm 1434uses at least the 1435.Ev HOME , 1436.Ev SHELL , 1437.Ev DISPLAY , 1438and 1439.Ev TERM 1440environment variables. 1441Other environment variables may be propagated 1442to the other side via the 1443.Dv TELNET ENVIRON 1444option. 1445.Sh FILES 1446.Bl -tag -width ~/.telnetrc -compact 1447.It Pa ~/.telnetrc 1448user customized telnet startup values 1449.El 1450.Sh SEE ALSO 1451.Xr rlogin 1 , 1452.Xr rsh 1 , 1453.Xr hosts 5 , 1454.Xr nologin 5 , 1455.Xr telnetd 8 1456.Sh HISTORY 1457The 1458.Nm 1459command appeared in 1460.Bx 4.2 . 1461.Pp 1462IPv6 support was added by WIDE/KAME project. 1463.Sh NOTES 1464On some remote systems, echo has to be turned off manually when in 1465\*(Lqold line by line\*(Rq mode. 1466.Pp 1467In \*(Lqold line by line\*(Rq mode or 1468.Dv LINEMODE 1469the terminal's 1470.Ic eof 1471character is only recognized (and sent to the remote system) 1472when it is the first character on a line. 1473