Telnet X.3 PAD option (RFC1053)
Original Publication Date: 1988-Apr-01
Included in the Prior Art Database: 2019-Feb-15
Internet Society Requests For Comment (RFCs)
S. Levy: AUTHOR [+1]
This RFC proposes a new option to Telnet for the Internet community, and requests discussion and suggestions for improvements.
Network Working Group S. Levy Request for Comments: 1053 T. Jacobson Minnesota Supercomputer Center April 1988
Telnet X.3 PAD Option
Status of this Memo
This RFC proposes a new option to Telnet for the Internet community, and requests discussion and suggestions for improvements. Distribution of this memo is unlimited.
1. Command name and code
2. Command meanings
IAC DO X.3-PAD
The issuing telnet requests that its peer perform X.3-PAD functions, or accepts an offer to do so.
IAC DON’T X.3-PAD
The issuing telnet demands that its peer not perform or cease performing X.3-PAD functions.
IAC WILL X.3-PAD
The issuing telnet offers to perform X.3-PAD functions or confirms that it will do so.
IAC WON’T X.3-PAD
The issuing telnet refuses to perform X.3-PAD functions or indicates that it is ceasing to handle them.
Typically a server (host) telnet will use DO and DON’T, while a client (user) telnet will use WILL and WON’T. For convenience, in the rest of this RFC ’host’ and ’user’ telnets refer to those saying ’DO X.3-PAD’ or ’WILL X.3-PAD’ respectively.
Both telnet peers may use this option without confusion, as all messages unambiguously identify whether they come from the host
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RFC 1053 Telnet X.3 PAD Option April 1988
("DO") or the user ("WILL") side.
Once DO and WILL have been exchanged, the host ("DO") telnet may send the following messages:
IAC SB X.3-PAD SET <param1> <value1> ... IAC SE IAC SB X.3-PAD RESPONSE-SET <param1> <value1> ... IAC SE IAC SB X.3-PAD SEND IAC SE
while the user ("WILL") telnet may send the following messages:
IAC SB X.3-PAD IS <param1> <value1> ... IAC SE IAC SB X.3-PAD RESPONSE-IS <param1> <value1> ... IAC SE
The code for SET is 0 The code for RESPONSE-SET is 1 The code for IS is 2 The code for RESPONSE-IS is 3 The code for SEND is 4
Messages listing parameter-value pairs may contain any number of such pairs, including zero. Each parameter and each value occupies one octet, except that 255 (IAC) is doubled wherever it appears.
3. Default conditions
The initial state is DON’T X.3-PAD, WON’T X.3-PAD. This RFC does not specify default values for most X.3 parameters. If the host telnet wishes a particular initial state (as it normally will), it should negotiate for it after exchange of DO/WILL messages.
X.3-PAD parameter values need not be preserved except when DO/WILL X.3-PAD is in effect. Thus if a host enables ("DO") X.3-PAD, negotiates about some parameters, then for some reason disables ("DONT") and later re-enables X.3-PAD, it must renegotiate any parameters it cares about.
Keeping in mind that the host telnet may not recognize all the parameters known to the user telnet, it is suggested that the user telnet’s initial parameters allow a reasonable level of service even if they are never changed (e.g., it would be unwise to begin with all data forwarding conditions disabled). Extensions to X.3 should default to states resembling normal X.3 service where possible.
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