1f060403bSbostic.\" Copyright (c) 1983, 1993 2f060403bSbostic.\" The Regents of the University of California. All rights reserved. 308fa8b2fSmckusick.\" 479069e29Scael.\" %sccs.include.redist.man% 508fa8b2fSmckusick.\" 6*d80f734cSah.\" @(#)telnetd.8 8.4 (Berkeley) 06/01/94 753bd74d7Sbostic.\" 8bfa5000bSdab.Dd 9bfa5000bSdab.Dt TELNETD 8 10bfa5000bSdab.Os BSD 4.2 11bfa5000bSdab.Sh NAME 12bfa5000bSdab.Nm telnetd 13bfa5000bSdab.Nd DARPA 14bfa5000bSdab.Tn TELNET 15bfa5000bSdabprotocol server 16bfa5000bSdab.Sh SYNOPSIS 17bfa5000bSdab.Nm /usr/libexec/telnetd 18fda9006dSdab.Op Fl BUhlkns 19bfa5000bSdab.Op Fl D Ar debugmode 20bfa5000bSdab.Op Fl I Ns Ar initid 21bfa5000bSdab.Op Fl S Ar tos 22bfa5000bSdab.Op Fl X Ar authtype 23fda9006dSdab.Op Fl a Ar authmode 24fda9006dSdab.Op Fl edebug 25fda9006dSdab.Op Fl r Ns Ar lowpty-highpty 26fda9006dSdab.Op Fl u Ar len 27bfa5000bSdab.Op Fl debug Op Ar port 28bfa5000bSdab.Sh DESCRIPTION 29bfa5000bSdabThe 30bfa5000bSdab.Nm telnetd 31bfa5000bSdabcommand is a server which supports the 32bfa5000bSdab.Tn DARPA 33bfa5000bSdabstandard 34bfa5000bSdab.Tn TELNET 35292dc983Sminshallvirtual terminal protocol. 36bfa5000bSdab.Nm Telnetd 37bfa5000bSdabis normally invoked by the internet server (see 38bfa5000bSdab.Xr inetd 8 ) 39bfa5000bSdabfor requests to connect to the 40bfa5000bSdab.Tn TELNET 41292dc983Sminshallport as indicated by the 42bfa5000bSdab.Pa /etc/services 43292dc983Sminshallfile (see 44bfa5000bSdab.Xr services 5 ) . 45bfa5000bSdabThe 46bfa5000bSdab.Fl debug 47bfa5000bSdaboption may be used to start up 48bfa5000bSdab.Nm telnetd 49ce93a3c8Sbormanmanually, instead of through 50bfa5000bSdab.Xr inetd 8 . 51bfa5000bSdabIf started up this way, 52bfa5000bSdab.Ar port 53bfa5000bSdabmay be specified to run 54bfa5000bSdab.Nm telnetd 55bfa5000bSdabon an alternate 56bfa5000bSdab.Tn TCP 57bfa5000bSdabport number. 58bfa5000bSdab.Pp 59bfa5000bSdabThe 60bfa5000bSdab.Nm telnetd 61bfa5000bSdabcommand accepts the following options: 62bfa5000bSdab.Bl -tag -width "-a authmode" 63bfa5000bSdab.It Fl a Ar authmode 64bfa5000bSdabThis option may be used for specifying what mode should 65bfa5000bSdabbe used for authentication. 66bfa5000bSdabNote that this option is only useful if 67bfa5000bSdab.Nm telnetd 68bfa5000bSdabhas been compiled with support for the 69bfa5000bSdab.Dv AUTHENTICATION 70bfa5000bSdaboption. 71bfa5000bSdabThere are several valid values for 72bfa5000bSdab.Ar authmode: 73bfa5000bSdab.Bl -tag -width debug 74bfa5000bSdab.It debug 75bfa5000bSdabTurns on authentication debugging code. 76bfa5000bSdab.It user 77bfa5000bSdabOnly allow connections when the remote user 78bfa5000bSdabcan provide valid authentication information 79bfa5000bSdabto identify the remote user, 80bfa5000bSdaband is allowed access to the specified account 81bfa5000bSdabwithout providing a password. 82bfa5000bSdab.It valid 83bfa5000bSdabOnly allow connections when the remote user 84bfa5000bSdabcan provide valid authentication information 85bfa5000bSdabto identify the remote user. 86bfa5000bSdabThe 87bfa5000bSdab.Xr login 1 88bfa5000bSdabcommand will provide any additional user verification 89bfa5000bSdabneeded if the remote user is not allowed automatic 90bfa5000bSdabaccess to the specified account. 91bfa5000bSdab.It other 92bfa5000bSdabOnly allow connections that supply some authentication information. 93bfa5000bSdabThis option is currently not supported 94bfa5000bSdabby any of the existing authentication mechanisms, 95bfa5000bSdaband is thus the same as specifying 96bfa5000bSdab.Fl a 97bfa5000bSdab.Cm valid . 98bfa5000bSdab.It none 99bfa5000bSdabThis is the default state. 100bfa5000bSdabAuthentication information is not required. 101bfa5000bSdabIf no or insufficient authentication information 102bfa5000bSdabis provided, then the 103bfa5000bSdab.Xr login 1 104bfa5000bSdabprogram will provide the necessary user 105bfa5000bSdabverification. 106bfa5000bSdab.It off 107bfa5000bSdabThis disables the authentication code. 108bfa5000bSdabAll user verification will happen through the 109bfa5000bSdab.Xr login 1 110bfa5000bSdabprogram. 111bfa5000bSdab.El 112bfa5000bSdab.It Fl B 113bfa5000bSdabSpecifies bftp server mode. In this mode, 114bfa5000bSdab.Nm telnetd 115bfa5000bSdabcauses login to start a 116bfa5000bSdab.Xr bftp 1 117bfa5000bSdabsession rather than the user's 118bfa5000bSdabnormal shell. In bftp daemon mode normal 119bfa5000bSdablogins are not supported, and it must be used 120bfa5000bSdabon a port other than the normal 121bfa5000bSdab.Tn TELNET 122bfa5000bSdabport. 123bfa5000bSdab.It Fl D Ar debugmode 124bfa5000bSdabThis option may be used for debugging purposes. 125bfa5000bSdabThis allows 126bfa5000bSdab.Nm telnetd 127bfa5000bSdabto print out debugging information 128bfa5000bSdabto the connection, allowing the user to see what 129bfa5000bSdab.Nm telnetd 130ce93a3c8Sbormanis doing. 131bfa5000bSdabThere are several possible values for 132bfa5000bSdab.Ar debugmode: 133bfa5000bSdab.Bl -tag -width exercise 134bfa5000bSdab.It Cm options 135bfa5000bSdabPrints information about the negotiation of 136bfa5000bSdab.Tn TELNET 137bfa5000bSdaboptions. 138bfa5000bSdab.It Cm report 139bfa5000bSdabPrints the 140bfa5000bSdab.Cm options 141bfa5000bSdabinformation, plus some additional information 142bfa5000bSdababout what processing is going on. 143bfa5000bSdab.It Cm netdata 144bfa5000bSdabDisplays the data stream received by 145bfa5000bSdab.Nm telnetd. 146bfa5000bSdab.It Cm ptydata 147bfa5000bSdabDisplays data written to the pty. 148bfa5000bSdab.It Cm exercise 149bfa5000bSdabHas not been implemented yet. 150bfa5000bSdab.El 151bfa5000bSdab.It Fl debug 152bfa5000bSdabEnables debugging on each socket created by 153bfa5000bSdab.Nm telnetd 154bfa5000bSdab(see 155bfa5000bSdab.Dv SO_DEBUG 156bfa5000bSdabin 157bfa5000bSdab.Xr socket 2 ) . 158bfa5000bSdab.It Fl edebug 159bfa5000bSdabIf 160bfa5000bSdab.Nm telnetd 161bfa5000bSdabhas been compiled with support for data encryption, then the 162bfa5000bSdab.Fl edebug 163bfa5000bSdaboption may be used to enable encryption debugging code. 164bfa5000bSdab.It Fl h 165bfa5000bSdabDisables the printing of host-specific information before 166bfa5000bSdablogin has been completed. 167bfa5000bSdab.It Fl I Ar initid 168bfa5000bSdabThis option is only applicable to 169bfa5000bSdab.Tn UNICOS 170bfa5000bSdabsystems prior to 7.0. 171bfa5000bSdabIt specifies the 172bfa5000bSdab.Dv ID 173bfa5000bSdabfrom 174bfa5000bSdab.Pa /etc/inittab 175bfa5000bSdabto use when init starts login sessions. The default 176bfa5000bSdab.Dv ID 177bfa5000bSdabis 178bfa5000bSdab.Dv fe. 179bfa5000bSdab.It Fl k 180bfa5000bSdabThis option is only useful if 181bfa5000bSdab.Nm telnetd 182bfa5000bSdabhas been compiled with both linemode and kludge linemode 183bfa5000bSdabsupport. If the 184bfa5000bSdab.Fl k 185bfa5000bSdaboption is specified, then if the remote client does not 186bfa5000bSdabsupport the 187bfa5000bSdab.Dv LINEMODE 188bfa5000bSdaboption, then 189bfa5000bSdab.Nm telnetd 190bfa5000bSdabwill operate in character at a time mode. 191bfa5000bSdabIt will still support kludge linemode, but will only 192bfa5000bSdabgo into kludge linemode if the remote client requests 193bfa5000bSdabit. 194bfa5000bSdab(This is done by by the client sending 195bfa5000bSdab.Dv DONT SUPPRESS-GO-AHEAD 196bfa5000bSdaband 197bfa5000bSdab.Dv DONT ECHO . ) 198bfa5000bSdabThe 199bfa5000bSdab.Fl k 200bfa5000bSdaboption is most useful when there are remote clients 201bfa5000bSdabthat do not support kludge linemode, but pass the heuristic 202bfa5000bSdab(if they respond with 203bfa5000bSdab.Dv WILL TIMING-MARK 204bfa5000bSdabin response to a 205bfa5000bSdab.Dv DO TIMING-MARK) 206bfa5000bSdabfor kludge linemode support. 207bfa5000bSdab.It Fl l 208bfa5000bSdabSpecifies line mode. Tries to force clients to use line- 209bfa5000bSdabat-a-time mode. 210bfa5000bSdabIf the 211bfa5000bSdab.Dv LINEMODE 212bfa5000bSdaboption is not supported, it will go 213bfa5000bSdabinto kludge linemode. 214bfa5000bSdab.It Fl n 215bfa5000bSdabDisable 216bfa5000bSdab.Dv TCP 217bfa5000bSdabkeep-alives. Normally 218bfa5000bSdab.Nm telnetd 219bfa5000bSdabenables the 220bfa5000bSdab.Tn TCP 221bfa5000bSdabkeep-alive mechanism to probe connections that 222bfa5000bSdabhave been idle for some period of time to determine 223bfa5000bSdabif the client is still there, so that idle connections 224bfa5000bSdabfrom machines that have crashed or can no longer 225bfa5000bSdabbe reached may be cleaned up. 226bfa5000bSdab.It Fl r Ar lowpty-highpty 227bfa5000bSdabThis option is only enabled when 228bfa5000bSdab.Nm telnetd 229bfa5000bSdabis compiled for 230bfa5000bSdab.Dv UNICOS. 231bfa5000bSdabIt specifies an inclusive range of pseudo-terminal devices to 232bfa5000bSdabuse. If the system has sysconf variable 233bfa5000bSdab.Dv _SC_CRAY_NPTY 234bfa5000bSdabconfigured, the default pty search range is 0 to 235bfa5000bSdab.Dv _SC_CRAY_NPTY; 236bfa5000bSdabotherwise, the default range is 0 to 128. Either 237bfa5000bSdab.Ar lowpty 238bfa5000bSdabor 239bfa5000bSdab.Ar highpty 240bfa5000bSdabmay be omitted to allow changing 241bfa5000bSdabeither end of the search range. If 242bfa5000bSdab.Ar lowpty 243bfa5000bSdabis omitted, the - character is still required so that 244bfa5000bSdab.Nm telnetd 245bfa5000bSdabcan differentiate 246bfa5000bSdab.Ar highpty 247bfa5000bSdabfrom 248bfa5000bSdab.Ar lowpty . 249bfa5000bSdab.It Fl s 250bfa5000bSdabThis option is only enabled if 251bfa5000bSdab.Nm telnetd 252bfa5000bSdabis compiled with support for 253bfa5000bSdab.Tn SecurID 254bfa5000bSdabcards. 255bfa5000bSdabIt causes the 256bfa5000bSdab.Fl s 257bfa5000bSdaboption to be passed on to 258bfa5000bSdab.Xr login 1 , 259bfa5000bSdaband thus is only useful if 260bfa5000bSdab.Xr login 1 261bfa5000bSdabsupports the 262bfa5000bSdab.Fl s 263bfa5000bSdabflag to indicate that only 264bfa5000bSdab.Tn SecurID 265bfa5000bSdabvalidated logins are allowed, and is 266bfa5000bSdabusually useful for controlling remote logins 267bfa5000bSdabfrom outside of a firewall. 268bfa5000bSdab.It Fl S Ar tos 269bfa5000bSdab.It Fl u Ar len 270bfa5000bSdabThis option is used to specify the size of the field 271bfa5000bSdabin the 272bfa5000bSdab.Dv utmp 273bfa5000bSdabstructure that holds the remote host name. 274bfa5000bSdabIf the resolved host name is longer than 275bfa5000bSdab.Ar len , 276bfa5000bSdabthe dotted decimal value will be used instead. 277bfa5000bSdabThis allows hosts with very long host names that 278bfa5000bSdaboverflow this field to still be uniquely identified. 279bfa5000bSdabSpecifying 280bfa5000bSdab.Fl u0 281bfa5000bSdabindicates that only dotted decimal addresses 282bfa5000bSdabshould be put into the 283bfa5000bSdab.Pa utmp 284bfa5000bSdabfile. 285*d80f734cSah.ne 1i 286bfa5000bSdab.It Fl U 287bfa5000bSdabThis option causes 288bfa5000bSdab.Nm telnetd 289bfa5000bSdabto refuse connections from addresses that 290bfa5000bSdabcannot be mapped back into a symbolic name 291bfa5000bSdabvia the 292bfa5000bSdab.Xr gethostbyaddr 3 293bfa5000bSdabroutine. 294bfa5000bSdab.It Fl X Ar authtype 295bfa5000bSdabThis option is only valid if 296bfa5000bSdab.Nm telnetd 297bfa5000bSdabhas been built with support for the authentication option. 298bfa5000bSdabIt disables the use of 299bfa5000bSdab.Ar authtype 300bfa5000bSdabauthentication, and 301bfa5000bSdabcan be used to temporarily disable 302bfa5000bSdaba specific authentication type without having to recompile 303bfa5000bSdab.Nm telnetd . 304bfa5000bSdab.El 305bfa5000bSdab.Pp 306bfa5000bSdab.Nm Telnetd 30708fa8b2fSmckusickoperates by allocating a pseudo-terminal device (see 308bfa5000bSdab.Xr pty 4 ) 30908fa8b2fSmckusickfor a client, then creating a login process which has 31008fa8b2fSmckusickthe slave side of the pseudo-terminal as 311bfa5000bSdab.Dv stdin , 312bfa5000bSdab.Dv stdout 31308fa8b2fSmckusickand 314bfa5000bSdab.Dv stderr . 315bfa5000bSdab.Nm Telnetd 316292dc983Sminshallmanipulates the master side of the pseudo-terminal, 317292dc983Sminshallimplementing the 318bfa5000bSdab.Tn TELNET 319292dc983Sminshallprotocol and passing characters 320292dc983Sminshallbetween the remote client and the login process. 321bfa5000bSdab.Pp 322292dc983SminshallWhen a 323bfa5000bSdab.Tn TELNET 324292dc983Sminshallsession is started up, 325bfa5000bSdab.Nm telnetd 326292dc983Sminshallsends 327bfa5000bSdab.Tn TELNET 328292dc983Sminshalloptions to the client side indicating 329bfa5000bSdaba willingness to do the 330bfa5000bSdabfollowing 331bfa5000bSdab.Tn TELNET 332bfa5000bSdaboptions, which are described in more detail below: 333bfa5000bSdab.Bd -literal -offset indent 334bfa5000bSdabDO AUTHENTICATION 335bfa5000bSdabWILL ENCRYPT 336bfa5000bSdabDO TERMINAL TYPE 337bfa5000bSdabDO TSPEED 338bfa5000bSdabDO XDISPLOC 339bfa5000bSdabDO NEW-ENVIRON 340bfa5000bSdabDO ENVIRON 341bfa5000bSdabWILL SUPPRESS GO AHEAD 342bfa5000bSdabDO ECHO 343bfa5000bSdabDO LINEMODE 344bfa5000bSdabDO NAWS 345bfa5000bSdabWILL STATUS 346bfa5000bSdabDO LFLOW 347bfa5000bSdabDO TIMING-MARK 348bfa5000bSdab.Ed 349bfa5000bSdab.Pp 350292dc983SminshallThe pseudo-terminal allocated to the client is configured 351bfa5000bSdabto operate in \*(lqcooked\*(rq mode, and with 352bfa5000bSdab.Dv XTABS and 353bfa5000bSdab.Dv CRMOD 35408fa8b2fSmckusickenabled (see 355bfa5000bSdab.Xr tty 4 ) . 356bfa5000bSdab.Pp 357bfa5000bSdab.Nm Telnetd 358bfa5000bSdabhas support for enabling locally the following 359bfa5000bSdab.Tn TELNET 360bfa5000bSdaboptions: 361bfa5000bSdab.Bl -tag -width "DO AUTHENTICATION" 362bfa5000bSdab.It "WILL ECHO" 363bfa5000bSdabWhen the 364bfa5000bSdab.Dv LINEMODE 365bfa5000bSdaboption is enabled, a 366bfa5000bSdab.Dv WILL ECHO 367bfa5000bSdabor 368bfa5000bSdab.Dv WONT ECHO 369bfa5000bSdabwill be sent to the client to indicate the 370bfa5000bSdabcurrent state of terminal echoing. 371bfa5000bSdabWhen terminal echo is not desired, a 372bfa5000bSdab.Dv WILL ECHO 373bfa5000bSdabis sent to indicate that 374bfa5000bSdab.Tn telnetd 375bfa5000bSdabwill take care of echoing any data that needs to be 376bfa5000bSdabechoed to the terminal, and then nothing is echoed. 377bfa5000bSdabWhen terminal echo is desired, a 378bfa5000bSdab.Dv WONT ECHO 379bfa5000bSdabis sent to indicate that 380bfa5000bSdab.Tn telnetd 381bfa5000bSdabwill not be doing any terminal echoing, so the 382bfa5000bSdabclient should do any terminal echoing that is needed. 383bfa5000bSdab.It "WILL BINARY" 384bfa5000bSdabIndicates that the client is willing to send a 385bfa5000bSdab8 bits of data, rather than the normal 7 bits 386bfa5000bSdabof the Network Virtual Terminal. 387bfa5000bSdab.It "WILL SGA" 388bfa5000bSdabIndicates that it will not be sending 389bfa5000bSdab.Dv IAC GA, 390bfa5000bSdabgo ahead, commands. 391bfa5000bSdab.It "WILL STATUS" 392bfa5000bSdabIndicates a willingness to send the client, upon 393bfa5000bSdabrequest, of the current status of all 394bfa5000bSdab.Tn TELNET 395bfa5000bSdaboptions. 396bfa5000bSdab.It "WILL TIMING-MARK" 397bfa5000bSdabWhenever a 398bfa5000bSdab.Dv DO TIMING-MARK 399bfa5000bSdabcommand is received, it is always responded 400bfa5000bSdabto with a 401bfa5000bSdab.Dv WILL TIMING-MARK 402*d80f734cSah.ne 1i 403bfa5000bSdab.It "WILL LOGOUT" 404bfa5000bSdabWhen a 405bfa5000bSdab.Dv DO LOGOUT 406bfa5000bSdabis received, a 407bfa5000bSdab.Dv WILL LOGOUT 408bfa5000bSdabis sent in response, and the 409bfa5000bSdab.Tn TELNET 410bfa5000bSdabsession is shut down. 411bfa5000bSdab.It "WILL ENCRYPT" 412bfa5000bSdabOnly sent if 413bfa5000bSdab.Nm telnetd 414bfa5000bSdabis compiled with support for data encryption, and 415bfa5000bSdabindicates a willingness to decrypt 416bfa5000bSdabthe data stream. 417bfa5000bSdab.El 418bfa5000bSdab.Pp 419bfa5000bSdab.Nm Telnetd 420bfa5000bSdabhas support for enabling remotely the following 421bfa5000bSdab.Tn TELNET 422bfa5000bSdaboptions: 423bfa5000bSdab.Bl -tag -width "DO AUTHENTICATION" 424bfa5000bSdab.It "DO BINARY" 425bfa5000bSdabSent to indicate that 426bfa5000bSdab.Tn telnetd 427bfa5000bSdabis willing to receive an 8 bit data stream. 428bfa5000bSdab.It "DO LFLOW" 429bfa5000bSdabRequests that the client handle flow control 430bfa5000bSdabcharacters remotely. 431bfa5000bSdab.It "DO ECHO" 432bfa5000bSdabThis is not really supported, but is sent to identify a 4.2BSD 433bfa5000bSdab.Xr telnet 1 434bfa5000bSdabclient, which will improperly respond with 435bfa5000bSdab.Dv WILL ECHO. 436bfa5000bSdabIf a 437bfa5000bSdab.Dv WILL ECHO 438bfa5000bSdabis received, a 439bfa5000bSdab.Dv DONT ECHO 440bfa5000bSdabwill be sent in response. 441bfa5000bSdab.It "DO TERMINAL-TYPE" 442bfa5000bSdabIndicates a desire to be able to request the 443bfa5000bSdabname of the type of terminal that is attached 444bfa5000bSdabto the client side of the connection. 445bfa5000bSdab.It "DO SGA" 446bfa5000bSdabIndicates that it does not need to receive 447bfa5000bSdab.Dv IAC GA, 448bfa5000bSdabthe go ahead command. 449bfa5000bSdab.It "DO NAWS" 450bfa5000bSdabRequests that the client inform the server when 451bfa5000bSdabthe window (display) size changes. 452bfa5000bSdab.It "DO TERMINAL-SPEED" 453bfa5000bSdabIndicates a desire to be able to request information 454bfa5000bSdababout the speed of the serial line to which 455bfa5000bSdabthe client is attached. 456bfa5000bSdab.It "DO XDISPLOC" 457bfa5000bSdabIndicates a desire to be able to request the name 458bfa5000bSdabof the X windows display that is associated with 459bfa5000bSdabthe telnet client. 460bfa5000bSdab.It "DO NEW-ENVIRON" 461bfa5000bSdabIndicates a desire to be able to request environment 462bfa5000bSdabvariable information, as described in RFC 1572. 463bfa5000bSdab.It "DO ENVIRON" 464bfa5000bSdabIndicates a desire to be able to request environment 465bfa5000bSdabvariable information, as described in RFC 1408. 466bfa5000bSdab.It "DO LINEMODE" 467bfa5000bSdabOnly sent if 468bfa5000bSdab.Nm telnetd 469bfa5000bSdabis compiled with support for linemode, and 470bfa5000bSdabrequests that the client do line by line processing. 471bfa5000bSdab.It "DO TIMING-MARK" 472bfa5000bSdabOnly sent if 473bfa5000bSdab.Nm telnetd 474bfa5000bSdabis compiled with support for both linemode and 475bfa5000bSdabkludge linemode, and the client responded with 476bfa5000bSdab.Dv WONT LINEMODE. 477bfa5000bSdabIf the client responds with 478bfa5000bSdab.Dv WILL TM, 479bfa5000bSdabthe it is assumed that the client supports 480bfa5000bSdabkludge linemode. 481bfa5000bSdabNote that the 482bfa5000bSdab.Op Fl k 483bfa5000bSdaboption can be used to disable this. 484bfa5000bSdab.It "DO AUTHENTICATION" 485bfa5000bSdabOnly sent if 486bfa5000bSdab.Nm telnetd 487bfa5000bSdabis compiled with support for authentication, and 488bfa5000bSdabindicates a willingness to receive authentication 489bfa5000bSdabinformation for automatic login. 490bfa5000bSdab.It "DO ENCRYPT" 491bfa5000bSdabOnly sent if 492bfa5000bSdab.Nm telnetd 493bfa5000bSdabis compiled with support for data encryption, and 494bfa5000bSdabindicates a willingness to decrypt 495bfa5000bSdabthe data stream. 496bfa5000bSdab.Sh ENVIRONMENT 497bfa5000bSdab.Sh FILES 498bfa5000bSdab.Pa /etc/services 499bfa5000bSdab.br 500bfa5000bSdab.Pa /etc/inittab 501bfa5000bSdab(UNICOS systems only) 502bfa5000bSdab.br 503bfa5000bSdab.Pa /etc/iptos 504bfa5000bSdab(if supported) 505bfa5000bSdab.br 506bfa5000bSdab.Pa /usr/ucb/bftp 507bfa5000bSdab(if supported) 508bfa5000bSdab.Sh "SEE ALSO" 509bfa5000bSdab.Xr telnet 1 , 510bfa5000bSdab.Xr login 1 , 511bfa5000bSdab.Xr bftp 1 512bfa5000bSdab(if supported) 513bfa5000bSdab.Sh STANDARDS 514bfa5000bSdab.Bl -tag -compact -width RFC-1572 515bfa5000bSdab.It Cm RFC-854 516bfa5000bSdab.Tn TELNET 517bfa5000bSdabPROTOCOL SPECIFICATION 518bfa5000bSdab.It Cm RFC-855 519bfa5000bSdabTELNET OPTION SPECIFICATIONS 520bfa5000bSdab.It Cm RFC-856 521bfa5000bSdabTELNET BINARY TRANSMISSION 522bfa5000bSdab.It Cm RFC-857 523bfa5000bSdabTELNET ECHO OPTION 524bfa5000bSdab.It Cm RFC-858 525bfa5000bSdabTELNET SUPPRESS GO AHEAD OPTION 526bfa5000bSdab.It Cm RFC-859 527bfa5000bSdabTELNET STATUS OPTION 528bfa5000bSdab.It Cm RFC-860 529bfa5000bSdabTELNET TIMING MARK OPTION 530bfa5000bSdab.It Cm RFC-861 531bfa5000bSdabTELNET EXTENDED OPTIONS - LIST OPTION 532bfa5000bSdab.It Cm RFC-885 533bfa5000bSdabTELNET END OF RECORD OPTION 534bfa5000bSdab.It Cm RFC-1073 535bfa5000bSdabTelnet Window Size Option 536bfa5000bSdab.It Cm RFC-1079 537bfa5000bSdabTelnet Terminal Speed Option 538bfa5000bSdab.It Cm RFC-1091 539bfa5000bSdabTelnet Terminal-Type Option 540bfa5000bSdab.It Cm RFC-1096 541bfa5000bSdabTelnet X Display Location Option 542bfa5000bSdab.It Cm RFC-1123 543bfa5000bSdabRequirements for Internet Hosts -- Application and Support 544bfa5000bSdab.It Cm RFC-1184 545bfa5000bSdabTelnet Linemode Option 546bfa5000bSdab.It Cm RFC-1372 547bfa5000bSdabTelnet Remote Flow Control Option 548bfa5000bSdab.It Cm RFC-1416 549bfa5000bSdabTelnet Authentication Option 550bfa5000bSdab.It Cm RFC-1411 551bfa5000bSdabTelnet Authentication: Kerberos Version 4 552bfa5000bSdab.It Cm RFC-1412 553bfa5000bSdabTelnet Authentication: SPX 554bfa5000bSdab.It Cm RFC-1571 555bfa5000bSdabTelnet Environment Option Interoperability Issues 556bfa5000bSdab.It Cm RFC-1572 557bfa5000bSdabTelnet Environment Option 558bfa5000bSdab.Sh BUGS 559292dc983SminshallSome 560bfa5000bSdab.Tn TELNET 561292dc983Sminshallcommands are only partially implemented. 562bfa5000bSdab.Pp 563292dc983SminshallBecause of bugs in the original 4.2 BSD 564bfa5000bSdab.Xr telnet 1 , 565bfa5000bSdab.Nm telnetd 566292dc983Sminshallperforms some dubious protocol exchanges to try to discover if the remote 567292dc983Sminshallclient is, in fact, a 4.2 BSD 568bfa5000bSdab.Xr telnet 1 . 569bfa5000bSdab.Pp 570bfa5000bSdabBinary mode 571292dc983Sminshallhas no common interpretation except between similar operating systems 572292dc983Sminshall(Unix in this case). 573bfa5000bSdab.Pp 574292dc983SminshallThe terminal type name received from the remote client is converted to 575292dc983Sminshalllower case. 576bfa5000bSdab.Pp 577bfa5000bSdab.Nm Telnetd 578292dc983Sminshallnever sends 579bfa5000bSdab.Tn TELNET 580bfa5000bSdab.Dv IAC GA 581bfa5000bSdab(go ahead) commands. 582