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1.1 ! root 1: .\" Copyright (c) 1983 Regents of the University of California. ! 2: .\" All rights reserved. The Berkeley software License Agreement ! 3: .\" specifies the terms and conditions for redistribution. ! 4: .\" ! 5: .\" @(#)telnet.1c 6.5 (Berkeley) 5/10/86 ! 6: .\" ! 7: .TH TELNET 1C "May 10, 1986" ! 8: .UC 5 ! 9: .SH NAME ! 10: telnet \- user interface to the \s-1TELNET\s0 protocol ! 11: .SH SYNOPSIS ! 12: telnet [ host [ port ] ] ! 13: .SH DESCRIPTION ! 14: .I Telnet ! 15: is used to communicate with another host using the ! 16: .B TELNET ! 17: protocol. ! 18: If ! 19: .I telnet ! 20: is invoked without arguments, it enters command mode, ! 21: indicated by its prompt (\*(lqtelnet>\*(rq). ! 22: In this mode, it accepts and executes the commands listed below. ! 23: If it is invoked with arguments, it performs an ! 24: .B open ! 25: command (see below) with those arguments. ! 26: .PP ! 27: Once a connection has been opened, ! 28: .I telnet ! 29: enters an input mode. ! 30: The input mode entered will be either \*(lqcharacter at a time\*(rq ! 31: or \*(lqline by line\*(rq ! 32: depending on what the remote system supports. ! 33: .PP ! 34: In \*(lqcharacter at a time\*(rq mode, most ! 35: text typed is immediately sent to the remote host for processing. ! 36: .PP ! 37: In \*(lqline by line\*(rq mode, all text is echoed locally, ! 38: and (normally) only completed lines are sent to the remote host. ! 39: The \*(lqlocal echo character\*(rq (initially \*(lq^E\*(rq) may be used ! 40: to turn off and on the local echo ! 41: (this would mostly be used to enter passwords ! 42: without the password being echoed). ! 43: .PP ! 44: In either mode, if the ! 45: .I localchars ! 46: toggle is TRUE (the default in line mode; see below), ! 47: the user's ! 48: .IR quit , ! 49: .IR intr , ! 50: and ! 51: .I flush ! 52: characters are trapped locally, and sent as ! 53: .B TELNET ! 54: protocol sequences to the remote side. ! 55: There are options (see ! 56: .B toggle ! 57: .I autoflush ! 58: and ! 59: .B toggle ! 60: .I autosynch ! 61: below) ! 62: which cause this action to flush subsequent output to the terminal ! 63: (until the remote host acknowledges the ! 64: .B TELNET ! 65: sequence) and flush previous terminal input ! 66: (in the case of ! 67: .I quit ! 68: and ! 69: .IR intr ). ! 70: .PP ! 71: While connected to a remote host, ! 72: .I telnet ! 73: command mode may be entered by typing the ! 74: .I telnet ! 75: \*(lqescape character\*(rq (initially \*(lq^]\*(rq). ! 76: When in command mode, the normal terminal editing conventions are available. ! 77: .PP ! 78: .B COMMANDS ! 79: .PP ! 80: The following commands are available. ! 81: Only enough of each command to uniquely identify it need be typed ! 82: (this is also true for arguments to the ! 83: .BR mode , ! 84: .BR set , ! 85: .BR toggle , ! 86: and ! 87: .B display ! 88: commands). ! 89: .PP ! 90: .TP ! 91: .B open \fIhost\fP \fR[\fP \fIport\fP \fR]\fP ! 92: .br ! 93: Open a connection to the named host. ! 94: If no port number ! 95: is specified, ! 96: .I telnet ! 97: will attempt to contact a ! 98: .B TELNET ! 99: server at the default port. ! 100: The host specification may be either a host name (see ! 101: .IR hosts (5)) ! 102: or an Internet address specified in the \*(lqdot notation\*(rq (see ! 103: .IR inet (3N)). ! 104: .TP ! 105: .B close ! 106: .br ! 107: Close a ! 108: .B TELNET ! 109: session and return to command mode. ! 110: .TP ! 111: .B quit ! 112: .br ! 113: Close any open ! 114: .B TELNET ! 115: session and exit ! 116: .IR telnet . ! 117: An end of file (in command mode) will also close a session and exit. ! 118: .TP ! 119: .B z ! 120: .br ! 121: Suspend ! 122: .IR telnet . ! 123: This command only works when the user is using the ! 124: .IR csh (1). ! 125: .TP ! 126: .B mode \fItype\fP ! 127: .br ! 128: .I Type ! 129: is either ! 130: .I line ! 131: (for \*(lqline by line\*(rq mode) ! 132: or ! 133: .I character ! 134: (for \*(lqcharacter at a time\*(rq mode). ! 135: The remote host is asked for permission to go into the requested mode. ! 136: If the remote host is capable of entering that mode, the requested ! 137: mode will be entered. ! 138: .TP ! 139: .B status ! 140: .br ! 141: Show the current status of ! 142: .IR telnet . ! 143: This includes the peer one is connected to, as well ! 144: as the current mode. ! 145: .TP ! 146: .B display \fR[\fP \fIargument...\fP \fR]\fP ! 147: .br ! 148: Displays all, or some, of the ! 149: .B set ! 150: and ! 151: .B toggle ! 152: values (see below). ! 153: .TP ! 154: .B ? \fR[\fP \fIcommand\fP \fR]\fP ! 155: .br ! 156: Get help. With no arguments, ! 157: .I telnet ! 158: prints a help summary. ! 159: If a command is specified, ! 160: .I telnet ! 161: will print the help information for just that command. ! 162: .TP ! 163: .B send \fIarguments\fP ! 164: .br ! 165: Sends one or more special character sequences to the remote host. ! 166: The following are the arguments which may be specified ! 167: (more than one argument may be specified at a time): ! 168: .RS ! 169: .TP ! 170: .I escape ! 171: .br ! 172: Sends the current ! 173: .I telnet ! 174: escape character (initially \*(lq^]\*(rq). ! 175: .TP ! 176: .I synch ! 177: .br ! 178: Sends the ! 179: .B TELNET SYNCH ! 180: sequence. ! 181: This sequence causes the remote system to discard all previously typed ! 182: (but not yet read) input. ! 183: This sequence is sent as TCP urgent ! 184: data (and may not work if the remote system is a 4.2 BSD system -- if ! 185: it doesn't work, a lower case \*(lqr\*(rq may be echoed on the terminal). ! 186: .TP ! 187: .I brk ! 188: .br ! 189: Sends the ! 190: .B TELNET BRK ! 191: (Break) sequence, which may have significance to the remote ! 192: system. ! 193: .TP ! 194: .I ip ! 195: .br ! 196: Sends the ! 197: .B TELNET IP ! 198: (Interrupt Process) sequence, which should cause the remote ! 199: system to abort the currently running process. ! 200: .TP ! 201: .I ao ! 202: .br ! 203: Sends the ! 204: .B TELNET AO ! 205: (Abort Output) sequence, which should cause the remote system to flush ! 206: all output ! 207: .B from ! 208: the remote system ! 209: .B to ! 210: the user's terminal. ! 211: .TP ! 212: .I ayt ! 213: .br ! 214: Sends the ! 215: .B TELNET AYT ! 216: (Are You There) ! 217: sequence, to which the remote system may or may not choose to respond. ! 218: .TP ! 219: .I ec ! 220: .br ! 221: Sends the ! 222: .B TELNET EC ! 223: (Erase Character) ! 224: sequence, which should cause the remote system to erase the last character ! 225: entered. ! 226: .TP ! 227: .I el ! 228: .br ! 229: Sends the ! 230: .B TELNET EL ! 231: (Erase Line) ! 232: sequence, which should cause the remote system to erase the line currently ! 233: being entered. ! 234: .TP ! 235: .I ga ! 236: .br ! 237: Sends the ! 238: .B TELNET GA ! 239: (Go Ahead) ! 240: sequence, which likely has no significance to the remote system. ! 241: .TP ! 242: .I nop ! 243: .br ! 244: Sends the ! 245: .B TELNET NOP ! 246: (No OPeration) ! 247: sequence. ! 248: .TP ! 249: .I ? ! 250: .br ! 251: Prints out help information for the ! 252: .B send ! 253: command. ! 254: .RE ! 255: .TP ! 256: .B set \fIargument value\fP ! 257: .br ! 258: Set any one of a number of ! 259: .I telnet ! 260: variables to a specific value. ! 261: The special value \*(lqoff\*(rq turns off the function associated with ! 262: the variable. ! 263: The values of variables may be interrogated with the ! 264: .B display ! 265: command. ! 266: The variables which may be specified are: ! 267: .RS ! 268: .TP ! 269: .I echo ! 270: .br ! 271: This is the value (initially \*(lq^E\*(rq) which, when in ! 272: \*(lqline by line\*(rq mode, toggles between doing local echoing ! 273: of entered characters (for normal processing), and suppressing ! 274: echoing of entered characters (for entering, say, a password). ! 275: .TP ! 276: .I escape ! 277: .br ! 278: This is the ! 279: .I telnet ! 280: escape character (initially \*(lq^[\*(rq) which causes entry ! 281: into ! 282: .I telnet ! 283: command mode (when connected to a remote system). ! 284: .TP ! 285: .I interrupt ! 286: .br ! 287: If ! 288: .I telnet ! 289: is in ! 290: .I localchars ! 291: mode (see ! 292: .B toggle ! 293: .I localchars ! 294: below) ! 295: and the ! 296: .I interrupt ! 297: character is typed, a ! 298: .B TELNET IP ! 299: sequence (see ! 300: .B send ! 301: .I ip ! 302: above) ! 303: is sent to the remote host. ! 304: The initial value for the interrupt character is taken to be ! 305: the terminal's ! 306: .B intr ! 307: character. ! 308: .TP ! 309: .I quit ! 310: .br ! 311: If ! 312: .I telnet ! 313: is in ! 314: .I localchars ! 315: mode (see ! 316: .B toggle ! 317: .I localchars ! 318: below) ! 319: and the ! 320: .I quit ! 321: character is typed, a ! 322: .B TELNET BRK ! 323: sequence (see ! 324: .B send ! 325: .I brk ! 326: above) ! 327: is sent to the remote host. ! 328: The initial value for the quit character is taken to be ! 329: the terminal's ! 330: .B quit ! 331: character. ! 332: .TP ! 333: .I flushoutput ! 334: .br ! 335: If ! 336: .I telnet ! 337: is in ! 338: .I localchars ! 339: mode (see ! 340: .B toggle ! 341: .I localchars ! 342: below) ! 343: and the ! 344: .I flushoutput ! 345: character is typed, a ! 346: .B TELNET AO ! 347: sequence (see ! 348: .B send ! 349: .I ao ! 350: above) ! 351: is sent to the remote host. ! 352: The initial value for the flush character is taken to be ! 353: the terminal's ! 354: .B flush ! 355: character. ! 356: .TP ! 357: .I erase ! 358: .br ! 359: If ! 360: .I telnet ! 361: is in ! 362: .I localchars ! 363: mode (see ! 364: .B toggle ! 365: .I localchars ! 366: below), ! 367: .B and ! 368: if ! 369: .I telnet ! 370: is operating in \*(lqcharacter at a time\*(rq mode, then when this ! 371: character is typed, a ! 372: .B TELNET EC ! 373: sequence (see ! 374: .B send ! 375: .I ec ! 376: above) ! 377: is sent to the remote system. ! 378: The initial value for the erase character is taken to be ! 379: the terminal's ! 380: .B erase ! 381: character. ! 382: .TP ! 383: .I kill ! 384: .br ! 385: If ! 386: .I telnet ! 387: is in ! 388: .I localchars ! 389: mode (see ! 390: .B toggle ! 391: .I localchars ! 392: below), ! 393: .B and ! 394: if ! 395: .I telnet ! 396: is operating in \*(lqcharacter at a time\*(rq mode, then when this ! 397: character is typed, a ! 398: .B TELNET EL ! 399: sequence (see ! 400: .B send ! 401: .I el ! 402: above) ! 403: is sent to the remote system. ! 404: The initial value for the kill character is taken to be ! 405: the terminal's ! 406: .B kill ! 407: character. ! 408: .TP ! 409: .I eof ! 410: .br ! 411: If ! 412: .I telnet ! 413: is operating in \*(lqline by line\*(rq mode, entering this character ! 414: as the first character on a line will cause this character to be ! 415: sent to the remote system. ! 416: The initial value of the eof character is taken to be the terminal's ! 417: .B eof ! 418: character. ! 419: .RE ! 420: .TP ! 421: .B toggle \fIarguments...\fP ! 422: .br ! 423: Toggle (between ! 424: TRUE ! 425: and ! 426: FALSE) ! 427: various flags that control how ! 428: .I telnet ! 429: responds to events. ! 430: More than one argument may be specified. ! 431: The state of these flags may be interrogated with the ! 432: .B display ! 433: command. ! 434: Valid arguments are: ! 435: .RS ! 436: .TP ! 437: .I localchars ! 438: .br ! 439: If this is ! 440: TRUE, ! 441: then the ! 442: .IR flush , ! 443: .IR interrupt , ! 444: .IR quit , ! 445: .IR erase , ! 446: and ! 447: .I kill ! 448: characters (see ! 449: .B set ! 450: above) are recognized locally, and transformed into (hopefully) appropriate ! 451: .B TELNET ! 452: control sequences ! 453: (respectively ! 454: .IR ao , ! 455: .IR ip , ! 456: .IR brk , ! 457: .IR ec , ! 458: and ! 459: .IR el ; ! 460: see ! 461: .B send ! 462: above). ! 463: The initial value for this toggle is TRUE in \*(lqline by line\*(rq mode, ! 464: and FALSE in \*(lqcharacter at a time\*(rq mode. ! 465: .TP ! 466: .I autoflush ! 467: .br ! 468: If ! 469: .I autoflush ! 470: and ! 471: .I localchars ! 472: are both ! 473: TRUE, ! 474: then when the ! 475: .IR ao , ! 476: .IR intr , ! 477: or ! 478: .I quit ! 479: characters are recognized (and transformed into ! 480: .B TELNET ! 481: sequences; see ! 482: .B set ! 483: above for details), ! 484: .I telnet ! 485: refuses to display any data on the user's terminal ! 486: until the remote system acknowledges (via a ! 487: .B TELNET ! 488: .I Timing Mark ! 489: option) ! 490: that it has processed those ! 491: .B TELNET ! 492: sequences. ! 493: The initial value for this toggle is TRUE if the terminal user had not ! 494: done an "stty noflsh", otherwise FALSE (see ! 495: .IR stty(1)). ! 496: .TP ! 497: .I autosynch ! 498: If ! 499: .I autosynch ! 500: and ! 501: .I localchars ! 502: are both ! 503: TRUE, ! 504: then when either the ! 505: .I intr ! 506: or ! 507: .I quit ! 508: characters is typed (see ! 509: .B set ! 510: above for descriptions of the ! 511: .I intr ! 512: and ! 513: .I quit ! 514: characters), the resulting ! 515: .B TELNET ! 516: sequence sent is followed by the ! 517: .B TELNET SYNCH ! 518: sequence. ! 519: This procedure ! 520: .B should ! 521: cause the remote system to begin throwing away all previously ! 522: typed input until both of the ! 523: .B TELNET ! 524: sequences have been read and acted upon. ! 525: The initial value of this toggle is FALSE. ! 526: .TP ! 527: .I crmod ! 528: .br ! 529: Toggle carriage return mode. ! 530: When this mode is enabled, most carriage return characters received from ! 531: the remote host will be mapped into a carriage return followed by ! 532: a line feed. ! 533: This mode does not affect those characters typed by the user, only ! 534: those received from the remote host. ! 535: This mode is not very useful unless the remote host ! 536: only sends carriage return, but never line feed. ! 537: The initial value for this toggle is FALSE. ! 538: .TP ! 539: .I debug ! 540: .br ! 541: Toggles socket level debugging (useful only to the ! 542: .IR super user ). ! 543: The initial value for this toggle is FALSE. ! 544: .TP ! 545: .I options ! 546: .br ! 547: Toggles the display of some internal ! 548: .I telnet ! 549: protocol processing (having to do with ! 550: .B TELNET ! 551: options). ! 552: The initial value for this toggle is FALSE. ! 553: .TP ! 554: .I netdata ! 555: .br ! 556: Toggles the display of all network data (in hexadecimal format). ! 557: The initial value for this toggle is FALSE. ! 558: .TP ! 559: .I ? ! 560: .br ! 561: Displays the legal ! 562: .B toggle ! 563: commands. ! 564: .RE ! 565: .SH BUGS ! 566: .PP ! 567: There is no adequate way for dealing with flow control. ! 568: .PP ! 569: On some remote systems, echo has to be turned off manually when in ! 570: \*(lqline by line\*(rq mode. ! 571: .PP ! 572: There is enough settable state to justify a ! 573: .RI . telnetrc ! 574: file. ! 575: .PP ! 576: No capability for a ! 577: .RI . telnetrc ! 578: file is provided. ! 579: .PP ! 580: In \*(lqline by line\*(rq mode, the terminal's ! 581: .I eof ! 582: character is only recognized (and sent to the remote system) ! 583: when it is the first character on a line.
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