-
Notifications
You must be signed in to change notification settings - Fork 4
/
Copy pathrfc0137.txt
619 lines (327 loc) · 19.3 KB
/
rfc0137.txt
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
Network Working Group T. C. O'Sullivan
Request for Comments: 137 Raytheon
NIC 6714 30 April 1971
TELNET Protocol
This is a request for comment and is being distributed in advance of
the Atlantic City meetings for review and comment prior to or during
discussions on TELNET in preparation for issuing an official
document.
It is also being distributed so that selected installations planning
to implement early versions of TELNET will have a common basis for
such implementation.
The proposed document is the result of the work of the committee. It
represents a TELNET protocol felt to be adequate for initial
implementation. A few recent suggestions by committee members and
others have been incorporated where even though not thoroughly
cleared with all members, the chairman felt that they clarified the
protocol or would tend to simplify implementation but not
substantially change the agreed-upon approach.
Readers are referenced to the following previous releases of
information:
1. Conventions for Using an IBM 2741 Terminal or a User Console for
Access to Network Server HOSTS
Joel Winett, RFC 110 (NIC #5809)
2. Level III Server Protocol for the Lincoln Laboratory 360/67 HOST
Joel Winett, RFC 109 (NIC #5808)
3. First Cut at a Proposed TELNET Protocol
J. Melvin, D. Watson, RFC 97 (NIC #5740)
4. ASCII Format for Network Interchange
V. Cerf, RFC 20 (NIC# 4722)
Another RFC will be distributed prior to the Atlantic City Meetings
containing many of the arguments supporting the proposal.
O'Sullivan [Page 1]
RFC 137 TELNET Protocol April 1971
TELNET PROTOCOL
A Proposed Document
T. O'Sullivan for the TELNET Committee
Will Crowther BBN
Bob Long SDC
John Melvin SRI-ARC
Bob Metcalf Harvard
Ed Meyer MAC
Tom O'Sullivan (Chairman) Raytheon
Joel Winett MIT-LL
O'Sullivan [Page 2]
RFC 137 TELNET Protocol April 1971
TELNET is a third-level protocol, the function of which is to make a
terminal (or process) at a using site appear to the system or a
process at a serving site as logically equivalent to a terminal
"directly" connected to the serving site. In performing this
function, the protocol attempts to minimize the amount of information
each HOST must keep about the characteristics of other HOSTS.
Definitions
Protocol Levels (see Figure 1)
Level 1
HOST-IMP protocol specified by BBN in NIC 5735, Specifications
for the Interconnection of a HOST, and an IMP (BBN Report 1822)
Level 2
HOST-HOST protocol performed by NCPs as described in Document
Number 1 (NIC 5413) and subsequent amendments, see RFC 107 (NIC
#5806)
One view of the NCP's function is that it takes information
from the net and routes it to receiving processes via
mechanisms internal to each HOST; conversely, processes use
the NCP, via internal system calls, to have information
routed to other processes in the net (via the other
processes' NCPs).
Level 3 (see Figure 2)
Level 3 is, by definition, the place to which and from which
the NCP communicates internally in its own host.
This level may be equivalent to the user process level in
some systems, but this may not be the case in all systems.
In using sites, the TELNET process operates at this level.
In serving sites, the TELNET server operates at this level.
Initial Connection Protocol (ICP)
An agreed-upon sequence of level 3 exchanges between two processes
which is, in general, used to synchronize the dialogue between the
processes, e.g., RFC 80 (NIC #5608) #1.
O'Sullivan [Page 3]
RFC 137 TELNET Protocol April 1971
Serving Site
The HOST into which the TELNET process is directing the user's
keyboard input and from which the TELNET process is receiving
control information and data effecting the user's terminal. At
the serving site, a TELNET server is executing.
Using Site
The HOST in which the TELNET process is executing.
Sending Site
The HOST transmitting data, could be either using site or serving
site.
Receiving Site
Converse of sending site.
User
The person or process "driving" the TELNET process.
In providing services the TELNET protocol will use established
network conventions, specifically the Network Control Program, and
Initial Connection Protocol referenced in the above definitions.
The TELNET protocol provides for a Network Virtual Terminal (NVT)
through which users may transmit and receive data over connections
between the using site and the serving site.
The code of the NVT will be full ASCII. The seven-bit code will be
transmitted in eight-bit bytes, the high order bit set to zero.
It will be the responsibility of the using site to provide its users
with a means of producing all 128 ASCII codes, as well as a selected
set of special TELNET control signals (see Figure 3).
O'Sullivan [Page 4]
RFC 137 TELNET Protocol April 1971
The ASCII character ESC will be employed by the user as an escape
signal indicating that the next character(s) has special meaning.
The meaning assigned to escape code will be serving site defined and
therefore may not be consistant across the network.
It will be the responsibility of the serving site to specify for
users how the NVT code will be used to represent the codes normally
generated by a local terminal. The serving sites specification of
this representation is expected, where reasonable, to map on a one-
for-one basis for ASCII graphics and controls that are provided
through local terminals. The serving site will also specify how the
escape conventions will be interpreted by the system.
The end of a line will be represented in the NVT as carriage return
followed by line feed.
The protocol assumes that at initially the serving site will not
provide any echo to the using site.
Each TELNET control signal for which code must be sent over the
connection will be represented in the NVT by an eight-bit code, with
the high order bit set to one. Following are the special codes
established to date. (U) indicates that in most implementations the
user would be expected to have the ability to signal the TELNET
process from his terminal to initiate the code.
Code X'A0'
Source: Both Sites (U)
Meaning: A DATA TYPE[1] signal indicating that code will be
transmitted by NVT, i.e., using the seven-bit ASCII
conventions.
Code X'80'
Source: Using Site (U)
Meaning: Order using site NCP to send an INS and insert X'80' in
data stream.
Code X'81'
Source: Using Site (U)
Meaning: Break or Attention
O'Sullivan [Page 5]
RFC 137 TELNET Protocol April 1971
Code X'82'
Source: Serving System
Meaning: Reverse Break
Code X'83'
Source: Both Sites
Meaning: I Echo
Code X'84'
Source: Both Sites
Meaning: You Echo
Code X'85'
Reserved
Code X'86'
Reserved
Code X'87'
Source: Both Sites
Meaning: This site has not implemented the following control code.
Code X'88'
Source: Both Sites
Meaning: [2]Return to control mode, i.e. next byte will be a
control signal, possible a new DATA TYPE.
Some special TELNET control signals are required to permit the user
on some systems to send control information to the using site TELNET
process. These do not require a corresponding control code for
transmission. The local TELNET control signals are:
1. Transmit all data to this point.
2. Suppress transmission of end of line, send all other data.
O'Sullivan [Page 6]
RFC 137 TELNET Protocol April 1971
Data is to be forwarded to the NCP for transmission as convenient,
but at least at the end of line, end of line suppression, and
transmit signals. If the normal line length of the sending site is
greater than the allocation given by the receiving site, the sending
sites TELNET process or TELNET server will be responsible for
breaking the line into convenient lengths and turning them over to
the NCP for transmission.
This document will be revised as necessary to provide conventions for
data types, in addition to the NVT ASCII type.
Footnotes:
[1] A one-byte DATA TYPE signal is sent as the first byte of data
over a connection. A default is employed if the first byte over a
connection has the high order bit set to zero, and it is assumed that
the seven-bit ASCII NVT convention will be employed. After initial
connection, the DATA TYPE may be changed (see code X'88'). Most
implementations and applications may expect the DATA TYPES to be
symmetrical at any point in time,(i.e. both using a serving site
using the same DATA TYPE.).
[2] A site receiving a DATA TYPE signal is to respond with a double
X'88' if the new DATA TYPE is acceptable.
O'Sullivan [Page 7]
RFC 137 TELNET Protocol April 1971
|<------- 32 ------->|<-8->|<-8->|<-- 16 -->|<-8->|<---
+--------------------+-----+-----+----------+-----+------------------
| leader | x |size | count | x | TEXT
+--------------------+-----+-----+----------+-----+------------------
|<---- level 1 ---->|
message leader
|<------------------ level 2 ------------------>|
message preamble
level 3
|<- message text..-->
Figure 1. Network Message on Link 2-31
Indicating Portions of Interest to Various Levels
USING HOST Serving HOST
-----------------------+ +----------------------
| |
\ | | /
\ -----------------| +-+ +-+ |-----------------/
\ NCP | |I| |I| | NCP /
\ ^ <--->|M|---NETWORK--|M|<---> ^ /
\ -----|-----+ | |P| |P| | +-----|-----/
\ v | | +-+ +-+ | | v /
USER \ | | | | TELNET / USER
PROCESSES, ) TELNET |--| |--|Protocol( PROCESS
Sub <===> | | | |Routing<--->Sub
Systems, / ^ | | | | ^^ \Systems
ETC /-----|-----+ | | +----||-----\ETC
/ TTY v <---> Local Local <===> TTY vv \
/ Handles | Terminals Terminals| Handles <===>
/-----------------| |-----------------\
/ | | \
| |
-----------------------+ +----------------------
<---> Current TELNET paths
<===> Candidate future TELNET paths
Figure 2. Current and Candidate Future TELNET Paths
O'Sullivan [Page 8]
RFC 137 TELNET Protocol April 1971
+---------------------------+----+----+----+----+----+----+----+----+
|\ b8 -> | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| \ b7 -> | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 |
| \ b6 -> | 0 | 0 | 1 | 1 | 0 | 0 | 1 | 1 |
|B \ b5 -> | 0 | 1 | 0 | 1 | 0 | 1 | 0 | 1 |
| I +---+---+---+---+------+----+----+----+----+----+----+----+----+
+ T | b | b | b | b |\COL->| | | | | | | | |
\ S| 4 | 3 | 2 | 1 | \ | | | | | | | | |
\ | | | | | |\ | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
\ | | | | | | | | | v \ | | | | | | | | |
\ | v | v | v | v |ROW \ | | | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 0 | 0 | 0 | 0 |NUL |DLE | SP | 0 | @ | P | \ | p |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 0 | 0 | 1 | 1 |SOH |DC1 | ! | 1 | A | Q | a | q |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 0 | 1 | 0 | 2 |STX |DC2 | " | 2 | B | R | b | r |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 0 | 1 | 1 | 3 |ETX |DC3 | # | 3 | C | S | c | s |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 1 | 0 | 0 | 4 |EOT |DC4 | $ | 4 | D | T | d | t |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 1 | 0 | 1 | 5 |ENQ |NAC | % | 5 | E | U | e | u |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 1 | 1 | 0 | 6 |ACK |SYN | & | 6 | F | V | f | v |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 1 | 1 | 1 | 7 |BEL |ETB | ' | 7 | G | W | g | w |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 0 | 0 | 0 | 8 | BS |CAN | ( | 8 | H | X | h | x |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 0 | 0 | 1 | 9 | HT | EM | ) | 9 | I | Y | i | y |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 0 | 1 | 0 | 10 | LF |SUB | * | : | J | Z | j | z |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 0 | 1 | 1 | 11 | VT |ESC | + | ; | K | [ | k | { |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 1 | 0 | 0 | 12 | FF | FS | , | < | L | \ | l | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 1 | 0 | 1 | 13 | CR | GS | - | = | M | ] | m | } |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 1 | 1 | 0 | 14 | S0 | RS | . | > | N | ^ | n | ~ |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 1 | 1 | 1 | 15 | S1 | US | / | ? | O | _ | o |DEL |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
Code Structure 8 7 6 5 4 3 2 1
--- --- --- --- --- --- --- --- --- ---
O'Sullivan [Page 9]
RFC 137 TELNET Protocol April 1971
+---------------------------+----+----+----+----+----+----+----+----+
|\ b8 -> | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| \ b7 -> | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 |
| \ b6 -> | 0 | 0 | 1 | 1 | 0 | 0 | 1 | 1 |
|B \ b5 -> | 0 | 1 | 0 | 1 | 0 | 1 | 0 | 1 |
| I +---+---+---+---+------+----+----+----+----+----+----+----+----+
+ T | b | b | b | b |\COL->| | | | | | | | |
\ S| 4 | 3 | 2 | 1 | \ | | | | | | | | |
\ | | | | | |\ | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
\ | | | | | | | | | v \ | | | | | | | | |
\ | v | v | v | v |ROW \ | | | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 0 | 0 | 0 | 0 |'80'| |'A0'| | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 0 | 0 | 1 | 1 |'81'| | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 0 | 1 | 0 | 2 |'82'| | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 0 | 1 | 1 | 3 |'83'| | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 1 | 0 | 0 | 4 |'84'| | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 1 | 0 | 1 | 5 |'85'| | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 1 | 1 | 0 | 6 |'86'| | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 0 | 1 | 1 | 1 | 7 |'87'| | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 0 | 0 | 0 | 8 |'88'| | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 0 | 0 | 1 | 9 | | | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 0 | 1 | 0 | 10 | | | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 0 | 1 | 1 | 11 | | | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 1 | 0 | 0 | 12 | | | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 1 | 0 | 1 | 13 | | | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 1 | 1 | 0 | 14 | | | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
| 1 | 1 | 1 | 1 | 15 | | | | | | | | |
+---+---+---+---+------+----+----+----+----+----+----+----+----+
'XX' = HEX designation for codes assigned to TELNET Control Signals.
Figure 3. Official Network Virtual Terminal Code
O'Sullivan [Page 10]
RFC 137 TELNET Protocol April 1971
[This RFC was put into machine readable form for entry]
[into the online RFC archives by Sergio Kleiman, 8/01]
O'Sullivan [Page 11]