1.\" Copyright (c) 1983, 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.\" @(#)telnetd.8 8.4 (Berkeley) 6/1/94
33.\"
34.Dd June 1, 1994
35.Dt TELNETD 8
36.Os BSD 4.2
37.Sh NAME
38.Nm telnetd
39.Nd DARPA
40.Tn TELNET
41protocol server
42.Sh SYNOPSIS
43.Nm telnetd
44.Op Fl BUhkln
45.Op Fl D Ar debugmode
46.Op Fl S Ar tos
47.Op Fl X Ar authtype
48.Op Fl a Ar authmode
49.Op Fl r Ns Ar lowpty-highpty
50.Op Fl u Ar len
51.Op Fl debug
52.Op Fl L Ar /bin/login
53.Op Ar port
54.Sh DESCRIPTION
55The
56.Nm telnetd
57command is a server which supports the
58.Tn DARPA
59standard
60.Tn TELNET
61virtual terminal protocol.
62.Nm Telnetd
63is normally invoked by the internet server (see
64.Xr inetd 8 )
65for requests to connect to the
66.Tn TELNET
67port as indicated by the
68.Pa /etc/services
69file (see
70.Xr services 5 ) .
71The
72.Fl debug
73option may be used to start up
74.Nm telnetd
75manually, instead of through
76.Xr inetd 8 .
77If started up this way,
78.Ar port
79may be specified to run
80.Nm telnetd
81on an alternate
82.Tn TCP
83port number.
84.Pp
85The
86.Nm telnetd
87command accepts the following options:
88.Bl -tag -width "-a authmode"
89.It Fl a Ar authmode
90This option may be used for specifying what mode should
91be used for authentication.
92Note that this option is only useful if
93.Nm telnetd
94has been compiled with support for the
95.Dv AUTHENTICATION
96option.
97There are several valid values for
| 1.\" Copyright (c) 1983, 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.\" @(#)telnetd.8 8.4 (Berkeley) 6/1/94
33.\"
34.Dd June 1, 1994
35.Dt TELNETD 8
36.Os BSD 4.2
37.Sh NAME
38.Nm telnetd
39.Nd DARPA
40.Tn TELNET
41protocol server
42.Sh SYNOPSIS
43.Nm telnetd
44.Op Fl BUhkln
45.Op Fl D Ar debugmode
46.Op Fl S Ar tos
47.Op Fl X Ar authtype
48.Op Fl a Ar authmode
49.Op Fl r Ns Ar lowpty-highpty
50.Op Fl u Ar len
51.Op Fl debug
52.Op Fl L Ar /bin/login
53.Op Ar port
54.Sh DESCRIPTION
55The
56.Nm telnetd
57command is a server which supports the
58.Tn DARPA
59standard
60.Tn TELNET
61virtual terminal protocol.
62.Nm Telnetd
63is normally invoked by the internet server (see
64.Xr inetd 8 )
65for requests to connect to the
66.Tn TELNET
67port as indicated by the
68.Pa /etc/services
69file (see
70.Xr services 5 ) .
71The
72.Fl debug
73option may be used to start up
74.Nm telnetd
75manually, instead of through
76.Xr inetd 8 .
77If started up this way,
78.Ar port
79may be specified to run
80.Nm telnetd
81on an alternate
82.Tn TCP
83port number.
84.Pp
85The
86.Nm telnetd
87command accepts the following options:
88.Bl -tag -width "-a authmode"
89.It Fl a Ar authmode
90This option may be used for specifying what mode should
91be used for authentication.
92Note that this option is only useful if
93.Nm telnetd
94has been compiled with support for the
95.Dv AUTHENTICATION
96option.
97There are several valid values for
|
98.Ar authmode:
| 98.Ar authmode :
|
99.Bl -tag -width debug
100.It debug
101Turns on authentication debugging code.
102.It user
103Only allow connections when the remote user
104can provide valid authentication information
105to identify the remote user,
106and is allowed access to the specified account
107without providing a password.
108.It valid
109Only allow connections when the remote user
110can provide valid authentication information
111to identify the remote user.
112The
113.Xr login 1
114command will provide any additional user verification
115needed if the remote user is not allowed automatic
116access to the specified account.
117.It other
118Only allow connections that supply some authentication information.
119This option is currently not supported
120by any of the existing authentication mechanisms,
121and is thus the same as specifying
122.Fl a
123.Cm valid .
124.It otp
125Only allow authenticated connections (as with
126.Fl a
127.Cm user )
128and also logins with one-time passwords (OTPs). This option will call
129login with an option so that only OTPs are accepted. The user can of
130course still type secret information at the prompt.
131.It none
132This is the default state.
133Authentication information is not required.
134If no or insufficient authentication information
135is provided, then the
136.Xr login 1
137program will provide the necessary user
138verification.
139.It off
140This disables the authentication code.
141All user verification will happen through the
142.Xr login 1
143program.
144.El
145.It Fl B
146Ignored.
147.It Fl D Ar debugmode
148This option may be used for debugging purposes.
149This allows
150.Nm telnetd
151to print out debugging information
152to the connection, allowing the user to see what
153.Nm telnetd
154is doing.
155There are several possible values for
| 99.Bl -tag -width debug
100.It debug
101Turns on authentication debugging code.
102.It user
103Only allow connections when the remote user
104can provide valid authentication information
105to identify the remote user,
106and is allowed access to the specified account
107without providing a password.
108.It valid
109Only allow connections when the remote user
110can provide valid authentication information
111to identify the remote user.
112The
113.Xr login 1
114command will provide any additional user verification
115needed if the remote user is not allowed automatic
116access to the specified account.
117.It other
118Only allow connections that supply some authentication information.
119This option is currently not supported
120by any of the existing authentication mechanisms,
121and is thus the same as specifying
122.Fl a
123.Cm valid .
124.It otp
125Only allow authenticated connections (as with
126.Fl a
127.Cm user )
128and also logins with one-time passwords (OTPs). This option will call
129login with an option so that only OTPs are accepted. The user can of
130course still type secret information at the prompt.
131.It none
132This is the default state.
133Authentication information is not required.
134If no or insufficient authentication information
135is provided, then the
136.Xr login 1
137program will provide the necessary user
138verification.
139.It off
140This disables the authentication code.
141All user verification will happen through the
142.Xr login 1
143program.
144.El
145.It Fl B
146Ignored.
147.It Fl D Ar debugmode
148This option may be used for debugging purposes.
149This allows
150.Nm telnetd
151to print out debugging information
152to the connection, allowing the user to see what
153.Nm telnetd
154is doing.
155There are several possible values for
|
156.Ar debugmode:
| 156.Ar debugmode :
|
157.Bl -tag -width exercise
158.It Cm options
159Prints information about the negotiation of
160.Tn TELNET
161options.
162.It Cm report
163Prints the
164.Cm options
165information, plus some additional information
166about what processing is going on.
167.It Cm netdata
168Displays the data stream received by
| 157.Bl -tag -width exercise
158.It Cm options
159Prints information about the negotiation of
160.Tn TELNET
161options.
162.It Cm report
163Prints the
164.Cm options
165information, plus some additional information
166about what processing is going on.
167.It Cm netdata
168Displays the data stream received by
|
169.Nm telnetd.
| 169.Nm telnetd .
|
170.It Cm ptydata
171Displays data written to the pty.
172.It Cm exercise
173Has not been implemented yet.
174.El
175.It Fl h
176Disables the printing of host-specific information before
177login has been completed.
178.It Fl k
179.It Fl l
180Ignored.
181.It Fl n
182Disable
183.Dv TCP
184keep-alives. Normally
185.Nm telnetd
186enables the
187.Tn TCP
188keep-alive mechanism to probe connections that
189have been idle for some period of time to determine
190if the client is still there, so that idle connections
191from machines that have crashed or can no longer
192be reached may be cleaned up.
193.It Fl r Ar lowpty-highpty
194This option is only enabled when
195.Nm telnetd
196is compiled for
| 170.It Cm ptydata
171Displays data written to the pty.
172.It Cm exercise
173Has not been implemented yet.
174.El
175.It Fl h
176Disables the printing of host-specific information before
177login has been completed.
178.It Fl k
179.It Fl l
180Ignored.
181.It Fl n
182Disable
183.Dv TCP
184keep-alives. Normally
185.Nm telnetd
186enables the
187.Tn TCP
188keep-alive mechanism to probe connections that
189have been idle for some period of time to determine
190if the client is still there, so that idle connections
191from machines that have crashed or can no longer
192be reached may be cleaned up.
193.It Fl r Ar lowpty-highpty
194This option is only enabled when
195.Nm telnetd
196is compiled for
|
197.Dv UNICOS.
| 197.Dv UNICOS .
|
198It specifies an inclusive range of pseudo-terminal devices to
199use. If the system has sysconf variable
200.Dv _SC_CRAY_NPTY
201configured, the default pty search range is 0 to
| 198It specifies an inclusive range of pseudo-terminal devices to
199use. If the system has sysconf variable
200.Dv _SC_CRAY_NPTY
201configured, the default pty search range is 0 to
|
202.Dv _SC_CRAY_NPTY;
| 202.Dv _SC_CRAY_NPTY ;
|
203otherwise, the default range is 0 to 128. Either
204.Ar lowpty
205or
206.Ar highpty
207may be omitted to allow changing
208either end of the search range. If
209.Ar lowpty
210is omitted, the - character is still required so that
211.Nm telnetd
212can differentiate
213.Ar highpty
214from
215.Ar lowpty .
216.It Fl S Ar tos
217.It Fl u Ar len
218This option is used to specify the size of the field
219in the
220.Dv utmp
221structure that holds the remote host name.
222If the resolved host name is longer than
223.Ar len ,
224the dotted decimal value will be used instead.
225This allows hosts with very long host names that
226overflow this field to still be uniquely identified.
227Specifying
228.Fl u0
229indicates that only dotted decimal addresses
230should be put into the
231.Pa utmp
232file.
| 203otherwise, the default range is 0 to 128. Either
204.Ar lowpty
205or
206.Ar highpty
207may be omitted to allow changing
208either end of the search range. If
209.Ar lowpty
210is omitted, the - character is still required so that
211.Nm telnetd
212can differentiate
213.Ar highpty
214from
215.Ar lowpty .
216.It Fl S Ar tos
217.It Fl u Ar len
218This option is used to specify the size of the field
219in the
220.Dv utmp
221structure that holds the remote host name.
222If the resolved host name is longer than
223.Ar len ,
224the dotted decimal value will be used instead.
225This allows hosts with very long host names that
226overflow this field to still be uniquely identified.
227Specifying
228.Fl u0
229indicates that only dotted decimal addresses
230should be put into the
231.Pa utmp
232file.
|
233.ne 1i
| |
234.It Fl U
235This option causes
236.Nm telnetd
237to refuse connections from addresses that
238cannot be mapped back into a symbolic name
239via the
240.Xr gethostbyaddr 3
241routine.
242.It Fl X Ar authtype
243This option is only valid if
244.Nm telnetd
245has been built with support for the authentication option.
246It disables the use of
247.Ar authtype
248authentication, and
249can be used to temporarily disable
250a specific authentication type without having to recompile
251.Nm telnetd .
252.It Fl L pathname
253Specify pathname to an alternative login program.
254.El
255.Pp
256.Nm Telnetd
257operates by allocating a pseudo-terminal device (see
258.Xr pty 4 )
259for a client, then creating a login process which has
260the slave side of the pseudo-terminal as
261.Dv stdin ,
262.Dv stdout
263and
264.Dv stderr .
265.Nm Telnetd
266manipulates the master side of the pseudo-terminal,
267implementing the
268.Tn TELNET
269protocol and passing characters
270between the remote client and the login process.
271.Pp
272When a
273.Tn TELNET
274session is started up,
275.Nm telnetd
276sends
277.Tn TELNET
278options to the client side indicating
279a willingness to do the
280following
281.Tn TELNET
282options, which are described in more detail below:
283.Bd -literal -offset indent
284DO AUTHENTICATION
285WILL ENCRYPT
286DO TERMINAL TYPE
287DO TSPEED
288DO XDISPLOC
289DO NEW-ENVIRON
290DO ENVIRON
291WILL SUPPRESS GO AHEAD
292DO ECHO
293DO LINEMODE
294DO NAWS
295WILL STATUS
296DO LFLOW
297DO TIMING-MARK
298.Ed
299.Pp
300The pseudo-terminal allocated to the client is configured
301to operate in
302.Dq cooked
303mode, and with
304.Dv XTABS and
305.Dv CRMOD
306enabled (see
307.Xr tty 4 ) .
308.Pp
309.Nm Telnetd
310has support for enabling locally the following
311.Tn TELNET
312options:
313.Bl -tag -width "DO AUTHENTICATION"
314.It "WILL ECHO"
315When the
316.Dv LINEMODE
317option is enabled, a
318.Dv WILL ECHO
319or
320.Dv WONT ECHO
321will be sent to the client to indicate the
322current state of terminal echoing.
323When terminal echo is not desired, a
324.Dv WILL ECHO
325is sent to indicate that
326.Tn telnetd
327will take care of echoing any data that needs to be
328echoed to the terminal, and then nothing is echoed.
329When terminal echo is desired, a
330.Dv WONT ECHO
331is sent to indicate that
332.Tn telnetd
333will not be doing any terminal echoing, so the
334client should do any terminal echoing that is needed.
335.It "WILL BINARY"
336Indicates that the client is willing to send a
3378 bits of data, rather than the normal 7 bits
338of the Network Virtual Terminal.
339.It "WILL SGA"
340Indicates that it will not be sending
| 233.It Fl U
234This option causes
235.Nm telnetd
236to refuse connections from addresses that
237cannot be mapped back into a symbolic name
238via the
239.Xr gethostbyaddr 3
240routine.
241.It Fl X Ar authtype
242This option is only valid if
243.Nm telnetd
244has been built with support for the authentication option.
245It disables the use of
246.Ar authtype
247authentication, and
248can be used to temporarily disable
249a specific authentication type without having to recompile
250.Nm telnetd .
251.It Fl L pathname
252Specify pathname to an alternative login program.
253.El
254.Pp
255.Nm Telnetd
256operates by allocating a pseudo-terminal device (see
257.Xr pty 4 )
258for a client, then creating a login process which has
259the slave side of the pseudo-terminal as
260.Dv stdin ,
261.Dv stdout
262and
263.Dv stderr .
264.Nm Telnetd
265manipulates the master side of the pseudo-terminal,
266implementing the
267.Tn TELNET
268protocol and passing characters
269between the remote client and the login process.
270.Pp
271When a
272.Tn TELNET
273session is started up,
274.Nm telnetd
275sends
276.Tn TELNET
277options to the client side indicating
278a willingness to do the
279following
280.Tn TELNET
281options, which are described in more detail below:
282.Bd -literal -offset indent
283DO AUTHENTICATION
284WILL ENCRYPT
285DO TERMINAL TYPE
286DO TSPEED
287DO XDISPLOC
288DO NEW-ENVIRON
289DO ENVIRON
290WILL SUPPRESS GO AHEAD
291DO ECHO
292DO LINEMODE
293DO NAWS
294WILL STATUS
295DO LFLOW
296DO TIMING-MARK
297.Ed
298.Pp
299The pseudo-terminal allocated to the client is configured
300to operate in
301.Dq cooked
302mode, and with
303.Dv XTABS and
304.Dv CRMOD
305enabled (see
306.Xr tty 4 ) .
307.Pp
308.Nm Telnetd
309has support for enabling locally the following
310.Tn TELNET
311options:
312.Bl -tag -width "DO AUTHENTICATION"
313.It "WILL ECHO"
314When the
315.Dv LINEMODE
316option is enabled, a
317.Dv WILL ECHO
318or
319.Dv WONT ECHO
320will be sent to the client to indicate the
321current state of terminal echoing.
322When terminal echo is not desired, a
323.Dv WILL ECHO
324is sent to indicate that
325.Tn telnetd
326will take care of echoing any data that needs to be
327echoed to the terminal, and then nothing is echoed.
328When terminal echo is desired, a
329.Dv WONT ECHO
330is sent to indicate that
331.Tn telnetd
332will not be doing any terminal echoing, so the
333client should do any terminal echoing that is needed.
334.It "WILL BINARY"
335Indicates that the client is willing to send a
3368 bits of data, rather than the normal 7 bits
337of the Network Virtual Terminal.
338.It "WILL SGA"
339Indicates that it will not be sending
|
341.Dv IAC GA,
| 340.Dv IAC GA ,
|
342go ahead, commands.
343.It "WILL STATUS"
344Indicates a willingness to send the client, upon
345request, of the current status of all
346.Tn TELNET
347options.
348.It "WILL TIMING-MARK"
349Whenever a
350.Dv DO TIMING-MARK
351command is received, it is always responded
352to with a
353.Dv WILL TIMING-MARK
| 341go ahead, commands.
342.It "WILL STATUS"
343Indicates a willingness to send the client, upon
344request, of the current status of all
345.Tn TELNET
346options.
347.It "WILL TIMING-MARK"
348Whenever a
349.Dv DO TIMING-MARK
350command is received, it is always responded
351to with a
352.Dv WILL TIMING-MARK
|
354.ne 1i
| |
355.It "WILL LOGOUT"
356When a
357.Dv DO LOGOUT
358is received, a
359.Dv WILL LOGOUT
360is sent in response, and the
361.Tn TELNET
362session is shut down.
363.It "WILL ENCRYPT"
364Only sent if
365.Nm telnetd
366is compiled with support for data encryption, and
367indicates a willingness to decrypt
368the data stream.
369.El
370.Pp
371.Nm Telnetd
372has support for enabling remotely the following
373.Tn TELNET
374options:
375.Bl -tag -width "DO AUTHENTICATION"
376.It "DO BINARY"
377Sent to indicate that
378.Tn telnetd
379is willing to receive an 8 bit data stream.
380.It "DO LFLOW"
381Requests that the client handle flow control
382characters remotely.
383.It "DO ECHO"
384This is not really supported, but is sent to identify a 4.2BSD
385.Xr telnet 1
386client, which will improperly respond with
| 353.It "WILL LOGOUT"
354When a
355.Dv DO LOGOUT
356is received, a
357.Dv WILL LOGOUT
358is sent in response, and the
359.Tn TELNET
360session is shut down.
361.It "WILL ENCRYPT"
362Only sent if
363.Nm telnetd
364is compiled with support for data encryption, and
365indicates a willingness to decrypt
366the data stream.
367.El
368.Pp
369.Nm Telnetd
370has support for enabling remotely the following
371.Tn TELNET
372options:
373.Bl -tag -width "DO AUTHENTICATION"
374.It "DO BINARY"
375Sent to indicate that
376.Tn telnetd
377is willing to receive an 8 bit data stream.
378.It "DO LFLOW"
379Requests that the client handle flow control
380characters remotely.
381.It "DO ECHO"
382This is not really supported, but is sent to identify a 4.2BSD
383.Xr telnet 1
384client, which will improperly respond with
|
387.Dv WILL ECHO.
| 385.Dv WILL ECHO .
|
388If a
389.Dv WILL ECHO
390is received, a
391.Dv DONT ECHO
392will be sent in response.
393.It "DO TERMINAL-TYPE"
394Indicates a desire to be able to request the
395name of the type of terminal that is attached
396to the client side of the connection.
397.It "DO SGA"
398Indicates that it does not need to receive
| 386If a
387.Dv WILL ECHO
388is received, a
389.Dv DONT ECHO
390will be sent in response.
391.It "DO TERMINAL-TYPE"
392Indicates a desire to be able to request the
393name of the type of terminal that is attached
394to the client side of the connection.
395.It "DO SGA"
396Indicates that it does not need to receive
|
399.Dv IAC GA,
| 397.Dv IAC GA ,
|
400the go ahead command.
401.It "DO NAWS"
402Requests that the client inform the server when
403the window (display) size changes.
404.It "DO TERMINAL-SPEED"
405Indicates a desire to be able to request information
406about the speed of the serial line to which
407the client is attached.
408.It "DO XDISPLOC"
409Indicates a desire to be able to request the name
410of the X windows display that is associated with
411the telnet client.
412.It "DO NEW-ENVIRON"
413Indicates a desire to be able to request environment
414variable information, as described in RFC 1572.
415.It "DO ENVIRON"
416Indicates a desire to be able to request environment
417variable information, as described in RFC 1408.
418.It "DO LINEMODE"
419Only sent if
420.Nm telnetd
421is compiled with support for linemode, and
422requests that the client do line by line processing.
423.It "DO TIMING-MARK"
424Only sent if
425.Nm telnetd
426is compiled with support for both linemode and
427kludge linemode, and the client responded with
| 398the go ahead command.
399.It "DO NAWS"
400Requests that the client inform the server when
401the window (display) size changes.
402.It "DO TERMINAL-SPEED"
403Indicates a desire to be able to request information
404about the speed of the serial line to which
405the client is attached.
406.It "DO XDISPLOC"
407Indicates a desire to be able to request the name
408of the X windows display that is associated with
409the telnet client.
410.It "DO NEW-ENVIRON"
411Indicates a desire to be able to request environment
412variable information, as described in RFC 1572.
413.It "DO ENVIRON"
414Indicates a desire to be able to request environment
415variable information, as described in RFC 1408.
416.It "DO LINEMODE"
417Only sent if
418.Nm telnetd
419is compiled with support for linemode, and
420requests that the client do line by line processing.
421.It "DO TIMING-MARK"
422Only sent if
423.Nm telnetd
424is compiled with support for both linemode and
425kludge linemode, and the client responded with
|
428.Dv WONT LINEMODE.
| 426.Dv WONT LINEMODE .
|
429If the client responds with
| 427If the client responds with
|
430.Dv WILL TM,
| 428.Dv WILL TM ,
|
431the it is assumed that the client supports
432kludge linemode.
433Note that the
434.Op Fl k
435option can be used to disable this.
436.It "DO AUTHENTICATION"
437Only sent if
438.Nm telnetd
439is compiled with support for authentication, and
440indicates a willingness to receive authentication
441information for automatic login.
442.It "DO ENCRYPT"
443Only sent if
444.Nm telnetd
445is compiled with support for data encryption, and
446indicates a willingness to decrypt
447the data stream.
448.El
449.Sh ENVIRONMENT
450.Sh FILES
| 429the it is assumed that the client supports
430kludge linemode.
431Note that the
432.Op Fl k
433option can be used to disable this.
434.It "DO AUTHENTICATION"
435Only sent if
436.Nm telnetd
437is compiled with support for authentication, and
438indicates a willingness to receive authentication
439information for automatic login.
440.It "DO ENCRYPT"
441Only sent if
442.Nm telnetd
443is compiled with support for data encryption, and
444indicates a willingness to decrypt
445the data stream.
446.El
447.Sh ENVIRONMENT
448.Sh FILES
|
451.Pa /etc/services
452.br
453.Pa /etc/inittab
| 449.Bl -tag -width /etc/services -compact
450.It Pa /etc/services
451.It Pa /etc/inittab
|
454(UNICOS systems only)
| 452(UNICOS systems only)
|
455.br
456.Pa /etc/iptos
| 453.It Pa /etc/iptos
|
457(if supported)
| 454(if supported)
|
458.br
| 455.El
|
459.Sh "SEE ALSO"
460.Xr telnet 1 ,
461.Xr login 1
462.Sh STANDARDS
463.Bl -tag -compact -width RFC-1572
464.It Cm RFC-854
465.Tn TELNET
466PROTOCOL SPECIFICATION
467.It Cm RFC-855
468TELNET OPTION SPECIFICATIONS
469.It Cm RFC-856
470TELNET BINARY TRANSMISSION
471.It Cm RFC-857
472TELNET ECHO OPTION
473.It Cm RFC-858
474TELNET SUPPRESS GO AHEAD OPTION
475.It Cm RFC-859
476TELNET STATUS OPTION
477.It Cm RFC-860
478TELNET TIMING MARK OPTION
479.It Cm RFC-861
480TELNET EXTENDED OPTIONS - LIST OPTION
481.It Cm RFC-885
482TELNET END OF RECORD OPTION
483.It Cm RFC-1073
484Telnet Window Size Option
485.It Cm RFC-1079
486Telnet Terminal Speed Option
487.It Cm RFC-1091
488Telnet Terminal-Type Option
489.It Cm RFC-1096
490Telnet X Display Location Option
491.It Cm RFC-1123
492Requirements for Internet Hosts -- Application and Support
493.It Cm RFC-1184
494Telnet Linemode Option
495.It Cm RFC-1372
496Telnet Remote Flow Control Option
497.It Cm RFC-1416
498Telnet Authentication Option
499.It Cm RFC-1411
500Telnet Authentication: Kerberos Version 4
501.It Cm RFC-1412
502Telnet Authentication: SPX
503.It Cm RFC-1571
504Telnet Environment Option Interoperability Issues
505.It Cm RFC-1572
506Telnet Environment Option
507.El
508.Sh BUGS
509Some
510.Tn TELNET
511commands are only partially implemented.
512.Pp
513Because of bugs in the original 4.2 BSD
514.Xr telnet 1 ,
515.Nm telnetd
516performs some dubious protocol exchanges to try to discover if the remote
517client is, in fact, a 4.2 BSD
518.Xr telnet 1 .
519.Pp
520Binary mode
521has no common interpretation except between similar operating systems
522(Unix in this case).
523.Pp
524The terminal type name received from the remote client is converted to
525lower case.
526.Pp
527.Nm Telnetd
528never sends
529.Tn TELNET
530.Dv IAC GA
531(go ahead) commands.
| 456.Sh "SEE ALSO"
457.Xr telnet 1 ,
458.Xr login 1
459.Sh STANDARDS
460.Bl -tag -compact -width RFC-1572
461.It Cm RFC-854
462.Tn TELNET
463PROTOCOL SPECIFICATION
464.It Cm RFC-855
465TELNET OPTION SPECIFICATIONS
466.It Cm RFC-856
467TELNET BINARY TRANSMISSION
468.It Cm RFC-857
469TELNET ECHO OPTION
470.It Cm RFC-858
471TELNET SUPPRESS GO AHEAD OPTION
472.It Cm RFC-859
473TELNET STATUS OPTION
474.It Cm RFC-860
475TELNET TIMING MARK OPTION
476.It Cm RFC-861
477TELNET EXTENDED OPTIONS - LIST OPTION
478.It Cm RFC-885
479TELNET END OF RECORD OPTION
480.It Cm RFC-1073
481Telnet Window Size Option
482.It Cm RFC-1079
483Telnet Terminal Speed Option
484.It Cm RFC-1091
485Telnet Terminal-Type Option
486.It Cm RFC-1096
487Telnet X Display Location Option
488.It Cm RFC-1123
489Requirements for Internet Hosts -- Application and Support
490.It Cm RFC-1184
491Telnet Linemode Option
492.It Cm RFC-1372
493Telnet Remote Flow Control Option
494.It Cm RFC-1416
495Telnet Authentication Option
496.It Cm RFC-1411
497Telnet Authentication: Kerberos Version 4
498.It Cm RFC-1412
499Telnet Authentication: SPX
500.It Cm RFC-1571
501Telnet Environment Option Interoperability Issues
502.It Cm RFC-1572
503Telnet Environment Option
504.El
505.Sh BUGS
506Some
507.Tn TELNET
508commands are only partially implemented.
509.Pp
510Because of bugs in the original 4.2 BSD
511.Xr telnet 1 ,
512.Nm telnetd
513performs some dubious protocol exchanges to try to discover if the remote
514client is, in fact, a 4.2 BSD
515.Xr telnet 1 .
516.Pp
517Binary mode
518has no common interpretation except between similar operating systems
519(Unix in this case).
520.Pp
521The terminal type name received from the remote client is converted to
522lower case.
523.Pp
524.Nm Telnetd
525never sends
526.Tn TELNET
527.Dv IAC GA
528(go ahead) commands.
|