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+
+Network Working Group J. White
+Request for Comments: 206 Computer Research Lab, UCSB
+NIC: 7176 9 August 1971
+
+
+ A User TELNET
+ Description of an Initial Implementation
+
+PREFACE
+
+ The User TELNET described in this document has been implemented
+ within UCSB's Online System by Mark Krilanovich and makes teletype-
+ compatible time-sharing systems in the Net accessible to Online
+ System users.
+
+Contents
+
+ Page
+ I. Function................................................... 1
+ II. Invoking TELNET............................................ 2
+ III. The Virtual Teletype....................................... 5
+ IV. Returning to TELNET........................................ 11
+ V. Breaking TELNET Connections................................ 12
+ VI. Abnormal Network Conditions................................ 12
+
+FIGURES
+
+ Page
+ Figure 1. Network Sites........................................ 4
+ Figure 2. TELNET Character Set................................. 6
+ Figure 3. Connect Error Codes.................................. 13
+ Figure 4. Input Error Codes.................................... 13
+ Figure 5. Output Error Codes................................... 14
+
+I. Function
+
+ This document describes a program whose function is to make an Online
+ System terminal _appear_ to any teletype-compatible, time-sharing
+ system in the Network _as if it were directly connected to that
+ system_. By invoking this program from his terminal, an OLS user can
+ effectively dial up a system at another site and use it as if he were
+ a local user of that system. The program performs the following
+ major functions:
+
+ 1) it resolves keyboard and display device incompatibilities
+
+ 2) performs character set transformations, and
+
+
+
+
+White [Page 1]
+
+RFC 206 A User TELNET August 1971
+
+
+ 3) makes its presence and that of the Network transparent to the
+ user.
+
+ The program which performs these functions is called a _User TELNET_.
+ It operates in conjunction with another program called a _Server
+ TELNET_ executing at the site whose system is being used. A Server
+ TELNET exists at each site whose system is accessible from the Net.
+ Similarly, a User TELNET must exist at a site before users at that
+ site have access to remote systems.
+
+ User and Server TELNETs access the Net through their respective NCPs,
+ and operate under a Network-standard protocol which specifies the
+ hand-shaking procedure by which the two parties connect themselves to
+ one another, as well as the format of data sent over a pair of
+ Network connections established between them. A User TELNET makes
+ such protocol considerations transparent to its users.
+
+ The TELNET protocol is based upon the notion of a virtual teletype,
+ employing a 7-bit ASCII character set. The primary function of a
+ User TELNET, then, is to provide the means by which its users can
+ 'hit' all the keys on that virtual teletype. If the user's keyboard
+ happens in fact to actually be a teletype, then the mapping procedure
+ is a very simple one. However, in UCSB's case, where a user's input
+ device is an OLS keyboard (a device very different from a teletype),
+ the mapping is more complex.
+
+ The primary function of a Server TELNET is to map the keys on the
+ virtual teletype into that set of keys _its_ local users can push on
+ _their_ keyboards. Again, if those keyboards are teletypes, the
+ mapping done by the Server TELNET is straightforward. In other
+ cases, the task may be very complex.
+
+ A similar set of mappings transforms ouput generated by the remote
+ system into a form displayable on the user's output device (in UCSB's
+ case, this device is normally a storage scope).
+
+II. Invoking TELNET
+
+ This and succeeding sections describe a preliminary version of a User
+ TELNET (hereafter referred to simply as TELNET) currently implemented
+ within the Online System. This initial implementation does not
+ provide all of the services that a final version must provide, nor
+ does it provide all the conveniences that the next version will
+ offer. It's a first pass which will be upgraded in the near future.
+
+
+
+
+
+
+
+White [Page 2]
+
+RFC 206 A User TELNET August 1971
+
+
+ TELNET is accessible from NET, a subsystem (like MOLSF and COL) of
+ OLS. A user is by default prohibited from loading NET. To have
+ access to NET enabled fro his user number, a user need only contact
+ the Computer Center. Assuming the foregoing, Net can be loaded with
+ the key sequence:
+
+ KEYBOARD ENTRY OLS QUERY/RESPONSE
+ SYST WORK AREAS UPDATED
+ LOAD NET LOAD NET
+ RETURN FILE LOADED
+
+ or by specifying the system name 'NET' at login.
+
+ Once in NET, TELNET is invoked by going to Level II Real and hitting
+ _LOG_. TELNET responds with a query for site number. The user
+ should enter in decimal the number of the site (as indicated in
+ Figure 1) to which he desires access, followed by _RETURN_. TELNET
+ will then query the user for the Server TELNET's socket_number. By
+ convention, this number is normally 1, but in certain cases some
+ other socket may be appropriate. In any case, the user should enter
+ the socket number in decimal and hit _RETURN_. The dialogue, then,
+ goes like this:
+
+ KEYBOARD ENTRY OLS QUERY/RESPONSE
+ II LOG FOREIGN SITE NO. = (site number)
+ site number RETURN FOREIGN SCK NO. = 1
+ 1 RETURN
+
+ When the second RETURN is depressed, TELNET will attempt to contact
+ the designated Server TELNET and establish a duplex connection for
+ the user. Once the connection has been established, TELNET will
+ erase the tube and position the carriage to the upper left-hand
+ corner of the screen. From this point on, the user is effectively
+ connected to the remote system. TELNET enters a mode in which keys
+ pushed by the user are mapped into their virtual-teletype equivalents
+ and incoming text similarly transformed and displayed on the scope.
+ If the remote system to which the user is connected normally issues a
+ login message, that message will be the first to be displayed. In
+ any case, the user should proceed by logging in to the remote system
+ according to the conventions appropriate to that system.
+
+
+
+
+
+
+
+
+
+
+
+White [Page 3]
+
+RFC 206 A User TELNET August 1971
+
+
+ Figure 1.
+
+ Network Sites
+
+Institution Location Computer Site Site # Site #
+ Name (HEX) (DEC)
+------------------------------------------------------------------------
+UCLA Los Angeles Sigma-7 UCLA 01 1
+
+UCLA Los Angeles IBM 360/91 UCL1 41 65
+
+Stanford Research
+Institute Menlo Park PDP-10 SRI0 02 2
+
+Stanford Research
+Institute Menlo Park PDP-15 SRI1 42 66
+
+UCSB Santa Barbara IBM 360/75 UCSB 03 3
+
+University of Salt Lake City,
+Utah Utah PDP-10 UTAH 04 4
+
+Bolt, Beranek, Cambridge,
+and Newman Mass. PDP-10 BBN0 05 5
+
+Bolt, Beranek, Cambridge,
+and Newman Mass. DDP-516 BBN1 45 69
+
+MIT Cambridge,
+ Mass. GE 645 MIT0 06 6
+
+MIT Cambridge,
+ Mass. PDP-10 MIT1 46 70
+
+Rand
+Corporation Santa Monica IBM 1800 RAND 07 7
+ (IBM 360/65)
+
+System Development
+Corporation Santa Monica DDP-516 SDC 08 8
+ (IBM 360/67)
+
+Harvard Cambridge,
+University Mass. PDP-10 HRV0 09 9
+
+Harvard Cambridge,
+University Mass. PDP-1 HRV1 49 73
+
+
+
+
+White [Page 4]
+
+RFC 206 A User TELNET August 1971
+
+
+Lincoln Lexington,
+Laboratory (MIT)Mass. IBM 360/67 LINO 0A 10
+
+Lincoln Lexington,
+Laboratory (MIT)Mass. TX2 LIN1 4A 74
+
+Stanford
+University Stanford PDP-10 STAN 0B 11
+
+University of Urbana, Ill. PDP-11 ILl 0C 12
+Illinois
+
+Case Western
+Resevrve Cleveland,
+University Ohio PDP-10 CASE 0D 13
+
+Carnegie-Mellon Pittsburgh,
+University Pa. PDP-10 CARN 0E 14
+
+Burroughs Paoli, Pa. B-6500 BURR 0F 15
+ (Illiac IV)
+
+III. The Virtual Teletype
+
+ The algorithm by which TELNET maps the OLS keyboard into the virtual
+ teletype's character set, and by which it maps that same character
+ set into the set of characters which can be displayed on the user's
+ storage scope is defined in Figure 2. A line of that figure reads as
+ follows:
+
+ For line 11:
+
+ The key labeled 'LF' (meaning 'Line Feed') on the virtual
+ teletype, sometimes referred to as 'control-J', is struck by
+ pressing either _SUB_, _CASE J_, or [1] on an OLS keyboard.
+ TELNET sends to the remote system an 8-bit character with the
+ value X'0A'. Whenever 'LF' is received from the foreign system,
+ TELNET displays it by rolling the carriage down one line.
+
+ As indicated in the figure, _CASE_ substitutes for the CNTRL key on a
+ teletype. Hence, for example, 'control-C' is represented by the key
+ pair 'CASE C'. Note, however, that _CASE_ and 'C' are hit in
+ sequence, whereas on a teletype the CNTRL key is held down while 'C'
+ is struck. 'CASE A' - 'CASE Z' each have an equivalent on the upper
+ keyboard, and the position of that key on the upper keyboard
+ corresponds to that of its counterpart on the lower keyboard. Hence,
+ LS equivalent to CASE A.
+
+
+
+
+White [Page 5]
+
+RFC 206 A User TELNET August 1971
+
+
+ Although TELNET provides the user with the means for transmitting
+ both upper- and lower-case alphabetics (hitting 'A' sends a lower-
+ case 'A'; holding down _SHIFT_ and hitting 'A' sends upper-case 'A'),
+ there is no provision in OLS for displaying lower-case characters on
+ the storage scope. Hence, TELNET maps lower-case alphabetics into
+ upper-case before displaying them.
+
+ The four virtual teltype keys 'ENQ', 'ACK', 'BEL', and 'NAK' are
+ displayed by TELNET in a special manner. Two lines are reserved for
+ these characters at the top of the display area, and whenever TELNET
+ receives such a character from the remote system, it displays it in
+ its assigned position within the two-line field. TELNET always
+ positions those four characters at the top of the display area,
+ regardless of the user's current position on the scope, then returns
+ to it.
+
+ A storage scope has both positive and negative attributes relative to
+ a teletype. Display is much quieter on a scope than on a teletype.
+ However, the noise made by the return of a teletype carriage is often
+ a valuable cue to the user, frequently signifying that the previous
+ line of input from the user has been accepted by the system. As a
+ substitute for this particular cue, TELNET displays an underline
+ ('_') at the left edge on the next line whenever it receives a
+ carriage return (CR) from the remote system.
+
+ Figure 2. TELNET Character Set
+
+To | | Also |Push | Or |Code Sent |Upon receipt
+Send| (Explanation)| Known as |Either| |is (in hex)|Displayed as
+----+--------------+----------+------+---------+-----------+------------
+NUL |NULL | ^@ | [2] | | 00 |
+ | | | | | |
+SOH |Start of | [3]^A | LS |[4]CASE A| 01 |
+ | Heading | | | | |
+ | | | | | |
+STX |Start of Text | ^B | ATAN | CASE B | 02 |
+ | | | | | |
+ETX |End of Text | ^C | LOG | CASE C | 03 |
+ | | | | | |
+EOT |End of | | | | |
+ | Transmission| ^D | REFL | CASE D | 04 |
+ | | | | | |
+ENQ |Enquiry | ^E | [4] | CASE E | 05 | [5] <ENQ>
+ | | | | | |
+ACK |Acknowledge | ^F | UP | CASE F | 06 | <ACK>
+ | | | | | |
+BEL |Bell | ^G | DOWN | CASE G | 07 | <BELL>
+
+
+
+
+White [Page 6]
+
+RFC 206 A User TELNET August 1971
+
+
+BS |Backspace | ^H | EVAL | CASE H | 08 |
+ | | | | | |
+HT |Horizontal | | | | |
+ |Tab. | ^I | INV | CASE I, | 09 |
+ | | | | TAB | |
+ | | | | | |
+LF |Line Feed | ^J | SUB | CASE J, | 0A | Carriage
+ | | | | [1] | | rolled down
+ | | | | | |
+VT |Vertical Tab. | ^K | MAX | CASE K | 0B |
+ | | | | | |
+FF |Form Feed | ^L | MOD | CASE L | 0C |
+ | | | | | |
+CR |Carriage | | | | |
+ | Return | ^M | DEL | CASE M, | 0D |[6]Carriage
+ | | | | RETURN| | returned
+ | | | | | |
+SO |Shift Out | ^N | ARG | CASE N | 0E |
+ | | | | | |
+SI |Shift In | ^O | DIFF | CASE O | 0F |
+ | | | | | |
+DLE |Data Link | | | | |
+ | Escape | ^P | SUM | CASE P | 10 |
+ | | | | | |
+DC1 |Device | | | | |
+ | Control 1 | ^Q | [7] | CASE Q | 11 |
+ | | | | | |
+DC2 |Device | | | | |
+ | Control 2 | ^R | [8] | CASE R | 12 |
+ | | | | | |
+DC3 |Device | | | | |
+ | Control 3 | ^S | RS | CASE S | 13 |
+ | | | | | |
+DC4 |Device | | | | |
+ | Control 4 | ^T | SQ | CASE T | 14 |
+ | | | | | |
+NAK |Negative | | | | |
+ | Acknowledge | ^U | CONJ | CASE U | 15 | <NAK>
+ | | | | | |
+SYN |Synchronous | | | | |
+ | Idle | ^V | EXP | CASE V | 16 |
+ | | | | | |
+ETB |End of | | | | |
+ | Transmission| | | | |
+ | Block | ^W | [9] | CASE W | 17 |
+ | | | | | |
+CAN |Cancel | ^X | COS | CASE X | 18 |
+
+
+
+
+White [Page 7]
+
+RFC 206 A User TELNET August 1971
+
+
+EM |End of Medium | ^Y | SQRT | CASE Y | 19 |
+ | | | | | |
+SUB | Substitute | ^Z | SIN | CASE Z | 1A |
+ | | | | | |
+ESC | Escape |Alt Mode, | NEG | | 1B |
+ | | ^[ | | | |
+ | | | | | |
+FS | File | ^ | PROD | | 1C |
+ | Separator | | | | |
+ | | | | | |
+GS | Group | ^] | SORT | | 1D |
+ | Separator | | | | |
+ | | | | | |
+RS | Record | ^^ | CONV | | 1E |
+ | Separator | | | | |
+ | | | | | |
+US | Unit | ^<- | PWR | | 1F |
+ | Separator | | | | |
+ | | | | | |
+SP | Space | |SPACE | | 20 |blank
+ | | | | | |
+! | Exclamation | | ! | | 21 | !
+ | Point | | | | |
+ | | | | | |
+" | Quotation |Diaeresis | " | | 22 | "
+ | Marks | | | | |
+ | | | | | |
+# | Number Sign | | # | | 23 | #
+ | | | | | |
+$ | Dollar Sign | | $ | | 24 | $
+ | | | | | |
+% | Percent | | % | | 25 | %
+ | | | | | |
+& | Ampersand | | & | | 26 | &
+ | | | | | |
+' | Apostrophe |Acute | ' | | 27 | '
+ | | Accent, | | | |
+ | | Closing | | | |
+ | | Single | | | |
+ | | Quote | | | |
+ | | | | | |
+( | Opening | | | | 28 | (
+ | Parenthesis| | ( | | |
+ | | | | | |
+) | Closing | | | | 29 | (
+ | Parenthesis| | ( | | |
+ | | | | | |
+* | Asterick | | * | | 2A | *
+
+
+
+White [Page 8]
+
+RFC 206 A User TELNET August 1971
+
+
++ | Plus | | + | | 2B | +
+ | | | | | |
+, | Comma |Cedilla | , | | 2C | ,
+ | | | | | |
+- | Hyphen |Minus | - | | 2D | -
+ | | | | | |
+. | Period |Decimal | . | | 2E | .
+ | | Point | | | |
+ | | | | | |
+/ | Slant | | / | | 2F | /
+ | | | | | |
+: | Colon | | : | | 3A | :
+ | | | | | |
+; | Semicolon | | ; | | 3B | ;
+ | | | | | |
+< | Less than | | < | | 3C | <
+ | | | | | |
+= | Equals | | = | | 3D | =
+ | | | | | |
+> | Greater than | | > | | 3E | >
+ | | | | | |
+? | Question Mark| | ? | | 3F | ?
+ | | | | | |
+@ | Commercial At| | @ | | 40 | @
+ | | | | | |
+[ | Opening | | [ | | 5B | [
+ | Bracket | | | | |
+ | | | | | |
+\ | Reverse Slant| |CASE /| | 5C | \
+ | | | | | |
+] | Closing | | ] | | 5D | ]
+ | Bracket | | | | |
+ | | | | | |
+^ | Circumflex | | ^ | ^ | 5E | ^
+ | | | | | |
+_ | Underline | | <- | _ | 5F | _
+ | | | | | |
+` | Grave Accent | Opening |CASE `| | 60 |`
+ | | single | | | |
+ | | quote | | | |
+ | | | | | |
+{ | Opening Brace| |CASE (| | 7B | {
+ | | | | | |
+| | Vertical Line| | | | | 7C | |
+ | | | | | |
+} | Closing Brace| |CASE )| | 7D | }
+
+
+
+
+
+White [Page 9]
+
+RFC 206 A User TELNET August 1971
+
+
+~ | Tilde | Overline,| - | | 7E | ~
+ | | General | | | |
+ | | Accent | | | |
+ | | | | | |
+DEL | Delete | Rubout | BACK | | 7F |
+ | | | | | |
+0-9 | Numerics | | 0-9 | | 30-39 | 0-9
+ | | | | | |
+A-Z | Upper Case | |SHIFT | | 41-5A | A-Z
+ | Alphabetics | |[9] | | |
+ | | | A-Z | | |
+ | | | | | |
+a-z | Lower Case | | | | 61-7A | A-Z
+ | Alphabetics | | A-Z | | |
+ | | | | | |
+
+ Table Notes
+
+ [1] Down arrow
+ [2] Superscript 1
+ [3] Superscript 2
+ [4] Circle with Dot in the Middle
+ [5] Superscript 3
+ [6] Superscript 6
+ [7] Circle with Plus (+) in the Middle
+ [8] Circle with Slash (/) in the Middle
+ [9] Superscript 5
+
+ Notes for Figure 2. TELNET Character Set
+
+ Superscript 1 - All of the following keys send NULL:
+
+ SET, CLR, cent sign, Superscript 0-9
+
+ Superscript 2 - '^A' is read 'Control A'. Same for '^B', '^C', etc.
+
+ Superscript 3 - ENQ, ACK, BEL, and NAK are displayed as '<ENQ>',
+ '<ACK>', '<BELL>', and '<NAK>', respectively, in an
+ area at the top of the screen reserved especially for
+ those characters.
+
+ Superscript 4 - ^A is sent by hitting th keys 'CASE' and 'A' in turn.
+ Same for ^B, ^C, etc.
+
+ Superscript 5 - Upper case 'A' is sent by holding down the SHIFT key
+ while 'A' is struck. Same for upper case 'B', 'C',
+ etc.
+
+
+
+
+White [Page 10]
+
+RFC 206 A User TELNET August 1971
+
+
+ Superscript 6 - CR also causes an underline '_' to be displayed in
+ the left margin as a substitute for the often useful
+ cue provided by the noisy return of a teletype
+ carriage.
+
+ A storage scope is also a much faster display device than a teletype.
+ However, in some situations this apparent attribute can be
+ troublesome. In particular, when a system displays a whole series of
+ lines of text without requiring input from the user, the display may
+ be wrapped around from the bottom of the scope to the top, and begin
+ overlaying itself before the user has had some time to read it all.
+ In such cases, the following strategy is sometimes useful (and will
+ make sense once the next section -- Section IV -- has been read): hit
+ _II_ before the display begins to wrap around upon itself; the
+ display will stop. After the text has been read, erase the scope and
+ hit _LOG_ and display will resume.
+
+ If the user hits _ERASE_ while in TELNET, that key will have its
+ usual effect; it will have _no_effect upon the remote system.
+ However, because of a quirk in the current implementation of TELNET,
+ _ERASE_ will have the one additional effect of causing the display of
+ incoming text to be suspended until another key on the virtual
+ teletype is struck. The user is thus cautioned against erasing the
+ scope while waiting for a response from the remote system. However,
+ the user can extricate himself from the situation described by
+ following the _ERASE_ with NUL on the virtual teletype.
+
+IV. Returning to TELNET
+
+ The user can at any time escape from TELNET (and hence from the
+ remote system to which he is attached) by depressing a level key
+ (e.g., I, II,...,_SYST, TYPE, LIST_) or of course, by hitting
+ _RESET_. Any time thereafter, the user may return to TELNET by
+ hitting _II LOG_ (on NET) once again, and resume operation on his
+ remote system _exactly where he left off_. When _'II LOG'_ is
+ pressed this second time, instead of querying the user for site
+ number as before, TELNET will notice that the user is already
+ connected to a remote system and simply resume where _it_ left off.
+
+ After he escapes from TELNET and before he returns to it, the user
+ may engage himself in any other Online System activity short of
+ logging out but including changing systems, while still retaining the
+ option of subsequently returning to TELNET and resuming activity on
+ the remote system to which he remains connected. The user can
+ exploit this property of TELNET to obtain hard copy of a selected
+ portion of his dialogue with the remote system. The user simply
+ brings his system to the point at which a listing is thereby desired,
+ escapes from TELNET by hitting _'TYPE SEL' 1,4 RETURN'_, thereby
+
+
+
+White [Page 11]
+
+RFC 206 A User TELNET August 1971
+
+
+ selecting the line printer as a secondary output device, and then
+ returns to TELNET by pressing _'II LOG'_. All subsequent
+ communication with the remote system will be recorded for eventual
+ output on the printer. Logging off of OLS while escaped from TELNET
+ causes the TELNET connection to be broken automatically by the
+ system.
+
+V. Breaking TELNET Connections
+
+ At any time while the user is in contact with TELNET, after the
+ connection to the remote system has been established, the user may
+ terminate that connection by hitting _'CON RETURN'_. TELNET will
+ respond _'SOCKETS PURGED_'. \ subsequent call to TELNET (i.e., a
+ subsequent instance of _'II LOG'_) will illicit the original query
+ for remote site number. The user is then free to connect himself to
+ another foreign system.
+
+ The user is cautioned that breaking Network connections as just
+ described is not necessarily equivalent to logging out of the remote
+ system. Some Server TELNETs may, when they detect the breaking of
+ connections, log the user off of their system; others may leave the
+ user logged on. The user should be aware of the conventions of the
+ systems he uses and, where appropriate, log himself off before
+ breaking connections.
+
+ The key sequence _'I DEL RETURN'_ will also terminate a TELNET
+ connection, but all other connections that may have been previously
+ established using the operators of Level I are closed as well.
+
+VI. Abnormal Network Conditions
+
+ While the user is in TELNET and attached to a remote system, TELNET
+ monitors the user's Network connections. If any abnormal condition
+ is detected, it terminates its monitoring and issues a message of the
+ form:
+
+ {CONNECT}
+ {INPUT} ERROR - CODE = n
+ {OUTPUT}
+
+ where 'n' is one of the values listed in Figures 3-5. A CONNECT
+ error may occur during TELNET's initial attempt to establish
+ connections to the remote system; an INPUT error may occur when
+ TELNET attempts to extract incoming data from the NET; and an OUTPUT
+ error may occur as TELNET tries to insert outgoing data into the Net.
+
+
+
+
+
+
+White [Page 12]
+
+RFC 206 A User TELNET August 1971
+
+
+ Figure 3. Connect Error Codes
+
+ 4 - A previous invocation of TELNET left a local receive
+ socket open; the send socket is closed. Hit _'I DEL
+ RETURN'_.
+
+ 8 - A previous invocation of TELNET aborted, and _'I DEL
+ RETURN'_ failed to close the Network connections.
+ The remote site is probably dead.
+
+ 12 - All communication paths between UCSB and the
+ specified remote site are in use.
+
+ 16 - UCSB's NCP is running at capacity or is drained or
+ stopped.
+
+ 20 - The connection attempt was refused by the remote
+ site.
+
+ 28 - No such remote site.
+
+ 36 - Remote site was discovered to be dead.
+
+ 44 - The Operator has stopped or reset the NCP.
+
+ 60 - Either the specified remote site is not accepting
+ input from the net, or there was a failure in the
+ subnet.
+
+ 68 - The specified remote site has broken all existing
+ connections to UCSB.
+
+ 72 - The remote site is known to be dead.
+
+
+ Figure 4. Input Error Codes
+
+ 8 - Connections to the server TELNET at the remote site
+ have been broken.
+
+ 16 - Connections to the Server TELNET at the remote site
+ are being broken.
+
+ 52 - An interrupt was sent by the remote system. Resume
+ by hitting _LOG_.
+
+
+
+
+
+
+White [Page 13]
+
+RFC 206 A User TELNET August 1971
+
+
+ Figure 5. Output Error Codes
+
+ 8 - Connections to the Server TELNET at the remote site
+ have been broken.
+
+ 16 - Connections to the Server TELNET at the remote site
+ are being broken.
+
+ 20 - same as 8.
+
+ 36 - Remote site has died.
+
+ 44 - The Operator has stopped or reset the NCP.
+
+ 52 - An interrupt was sent by the remote system. Resume
+ by hitting _LOG_.
+
+ 60 - Either the remote site has stopped accepting input
+ from the Net or there was a failure in the subnet.
+
+ 64 - same as 60.
+
+ 68 - The remote site has broken all existing connections
+ to UCSB.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
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+
+White [Page 14]
+