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+
+
+Network Working Group S. Silverman
+Request for Comments: 933 MITRE-Washington
+ January 1985
+
+ OUTPUT MARKING TELNET OPTION
+
+
+Status of this Memo
+
+ This RFC proposes a new option for Telnet for the ARPA-Internet
+ community, and requests discussion and suggestions for improvements.
+ Distribution of this memo is unlimited.
+
+Overview
+
+ This proposed option would allow a Server-Telnet to send a banner to
+ a User-Telnet so that this banner would be displayed on the
+ workstation screen independently of the application software running
+ in the Server-Telnet.
+
+1. Command Name and Code
+
+ OUTMRK 27
+
+2. Command Meanings
+
+ IAC WILL OUTMRK
+
+ Sender is willing to send output marking information in a
+ subsequent sub-negotiation.
+
+ IAC WON'T OUTMRK
+
+ Sender refuses to send output marking information.
+
+ IAC DO OUTMRK
+
+ Sender is willing to receive output marking information in a
+ subsequent sub-negotiation.
+
+ IAC DON'T OUTMRK
+
+ Sender refuses to accept output marking information.
+
+ IAC SB OUTMRK CNTL data IAC SE
+
+ The sender requests receiver to use the data in this
+ subnegotiation as a marking for the normally transmitted Telnet
+ data until further notice. The CNTL octet indicates the position
+ of the marking (see below).
+
+
+
+Silverman [Page 1]
+
+
+
+RFC 933 January 1985
+Output Marking Telnet Option
+
+
+ IAC SB OUTMRK ACK IAC SE
+
+ The sender acknowledges the data and agrees to use it to perform
+ output marking (see below).
+
+ IAC SB OUTMRK NAK IAC SE
+
+ The sender objects to using the data to perform output marking
+ (see below).
+
+3. Default
+
+ WON'T OUTMRK
+
+ Output marking information will not be exchanged.
+
+ DON'T OUTMRK
+
+ Output marking information will not be exchanged.
+
+4. Motivation for the Option
+
+ The security architecture of some military systems identifies a
+ security level with each Telnet connection. There is a corresponding
+ need to display a security banner on visual display devices.
+ (Reference: Department of Defense Trusted Computer System Evaluation
+ Criteria, Section 3.1.1.3.2.3, Labeling Human-Readable Output.)
+
+ The output marking is currently done by transmitting the banner as
+ data within each screen of data. It would be more efficient to
+ transmit the data once with instructions and have User-Telnet
+ maintain the banner automatically without any additional
+ Server-Telnet action. This frees Server-Telnet from needing to know
+ the output device page size.
+
+ Under this proposal Server-Telnet would send an option sequence with
+ the command, a control flag, and the banner to be used. While
+ current systems use the top of the screen, it is conceivable other
+ systems would want to put the banner at the bottom or perhaps even
+ the side of the screen. This is the reason for the control flag.
+
+5. Description of the Option
+
+ Either side of the session can initiate the option; however, normally
+ it will be the server side that initiates the request to perform
+ output marking. Either the Server-Telnet sends "WILL OUTMRK" or the
+ User-Telnet sends a "DO OUTMRK". The party receiving the initial
+
+
+Silverman [Page 2]
+
+
+
+RFC 933 January 1985
+Output Marking Telnet Option
+
+
+ "WILL" (or "DO") would respond with "DO" (or "WILL") to accept the
+ option. Then Server-Telnet responds with the marking data. The
+ format of this is:
+
+ "IAC SB OUTMRK CNTL data IAC SE"
+
+ CNTL is the Control Flag described below,
+ the data is in ASCII.
+
+ If this is satisfactory, User-Telnet responds:
+
+ "IAC SB OUTMRK ACK IAC SE"
+
+ ACK is the ASCII ACK (6).
+
+ From this point, User-Telnet will have to translate any command which
+ uses cursor controls so that the application data is mapped to the
+ application part of the screen.
+
+ If the data passed in the subnegotiation field is unacceptable to
+ User-Telnet, then it responds with:
+
+ "IAC SB OUTMRK NAK IAC SE"
+
+ NAK is the ASCII NAK (21).
+
+ It is now up to Server-Telnet to start the sequence over again and
+ use "more acceptable" data (or possibly take other action such as
+ connection termination).
+
+ To terminate output marking, Server-Telnet transmits "WON'T OUTMRK".
+
+ If necessary, User-Telnet would notify Server-Telnet about the new
+ effective page size. User-Telnet would then map the output data to
+ the allowed usable space on the screen.
+
+ User-Telnet may request OUTMRK data or initiate setup of this
+ convention at anytime by transmitting "DO OUTMRK". If a WILL, DO
+ OUTMRK exchange is not followed by the OUTMRK subnegotiation of the
+ marking data, the User-Telnet may terminate the output marking option
+ by sending a "DON'T OUTMRK".
+
+
+
+
+
+
+
+
+Silverman [Page 3]
+
+
+
+RFC 933 January 1985
+Output Marking Telnet Option
+
+
+ Control Flag
+
+ The CNTL flag is defined as:
+
+ D = Default, the placement of the markings is up to
+ User-Telnet. This is the expected mode for most
+ interactions.
+
+ T = Top, this banner is to be used as the top of the screen.
+ If multiple output markings are desired, then T and B (or R
+ & L ) are to be used.
+
+ B = Bottom, this banner is to be used at the bottom of the
+ screen.
+
+ L = Left, markings on the left. (The precise meaning of this
+ is to be defined.)
+
+ R = Right, marking on right. (The precise meaning of this is
+ to be defined.)
+
+ Banner Data
+
+ The use of Carriage Return and Line Feed (CRLF) will be
+ interpreted as a end of line in the marking banner text. If the
+ user wants a multiline banner, CRLF will be used between each
+ line. No CRLF is needed at the end of the marking data.
+
+ To use multiple banners, all of the banners will be included in
+ one subnegotiation command of the form:
+
+ "IAC SB OUTMRK CNTL data GS CNTL data IAC SE"
+
+ where GS is the ASCII Group Separator (29) character.
+
+ User-Telnet will be responsible for positioning the marking banner
+ data on the screen.
+
+
+
+
+
+
+
+
+
+
+
+
+Silverman [Page 4]
+