RFC 933 (rfc933) - Page 2 of 4
Output marking Telnet option
Alternative Format: Original Text Document
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