Telnet terminal type option

　　Network Working Group Marvin Solomon

　　Request for Comments: 884 Edward Wimmers

　　University of Wisconsin - Madison

　　December 1983

　　TELNETTERMINAL TYPE OPTION

　　This RFCspecifies a standard for the ARPA Internet community. Hosts on　the ARPA Internet that exchange terminal type information within the　Telnet protocol are expected to adopt and implement this standard.

　　1. Command Name and Code

　　TERMINAL-TYPE 24

　　2. Command Meanings

　　IAC WILL TERMINAL-TYPE

　　Sender is willing to send terminal type information in a　subsequent sub-negotiation

　　IAC DO TERMINAL-TYPE

　　Sender is willing to receive terminal type information in a　subsequent sub-negotiation

　　IAC DON'T TERMINAL-TYPE

　　Sender refuses to accept terminal type information

　　IAC WON'T TERMINAL-TYPE

　　Sender refuses to send terminal type information

　　IAC SB TERMINAL-TYPE SEND IAC SE

　　Sender requests receiver to transmit his (the receiver's) terminal　type. The code for SEND is 1. (See below.)

　　IAC SB TERMINAL-TYPE IS ... IAC SE

　　Sender is stating the name of his terminal type. The code for IS　is 0. (See below.)

　　RFC884December 1983

　　3. Default

　　DON'T TERMINAL-TYPE

　　WON'T TERMINAL-TYPE

　　Terminal type information will not be exchanged.

　　4. Motivation for the Option

　　This option allows a telnet server to determine the type of terminal　connected to a user telnet program. The transmission of such　information does not immediately imply any change of processing.

　　However, the information may be passed to a process, which may alter　the data it sends to suit the particular characteristics of the　terminal. For example, some operating systems have a terminal driver　that accepts a code indicating the type of terminal being driven.

　　Using the TERMINAL TYPE and BINARY options, a telnet server program　on such a system could arrange to have terminals driven as if they　were directly connected, including such special functions as cursor　addressing, multiple colors, etc., not included in the Network　Virtual Terminal specification. This option fits into the normal　structure of TELNET options by deferring the actual transfer of　status information to the SB command.

　　5. Description of the Option

　　WILL and DO are used only to obtain and grant permission for future　discussion. The actual exchange of status information occurs within　option subcommands (IAC SB TERMINAL-TYPE...).

　　Once the two hosts have exchanged a WILL and a DO, the sender of the　WILL TERMINAL-TYPE is free to transmit type information, spontan-eously or in response to a request from the sender of the DO. At　worst, this may lead to transmitting the information twice. Only the　sender of the DO may send requests (IAC SB TERMINAL-TYPE SEND IAC SE)　and only the sender of the WILL may transmit actual type information　(within an IAC SB TERMINAL-TYPE IS ... IAC SE command).

　　The terminal type information is an NVT ASCII string. Within this　string, upper and lower case are considered equivalent. A few　terminal type names useful in the context of IBM systems are listed　below. It is anticipated that additional names will be added in the　future. The complete list of valid terminal types will be found in　the latest "Assigned Numbers" RFC.

　　RFC884December 1983

　　The following is an example of use of the option:

　　Host1: IAC DO TERMINAL-TYPE

　　Host2: IAC WILL TERMINAL-TYPE

　　(Host2 is now free to send status information at any time.

　　Solicitations from Host1 are NOT necessary. This should not　produce any dangerous race conditions. At worst, two IS's will　be sent.)

　　Host1 (perhaps): IAC SB TERMINAL-TYPE SEND IAC SE

　　Host2:

　　IAC SB TERMINAL-TYPE IS IBM-3278-2 IAC SE

　　6. Implementation Suggestions

　　The "terminal type" information may be any NVT ASCII string meaning-ful to both ends of the negotiation. The list of suggestions below　is intended to minimize confusion caused by alternative "spellings"　of the terminal type. For example, confusion would arise if one　party were to call a terminal "IBM3278-2" while the other called it　"IBM-3278/2". There is no negative acknowledgement for a terminal　type that is not understood, but certain other options (such as　switching to BINARY mode) may be refused if a valid terminal type　name has not been specified. In some cases, a particular terminal　may be known by more than one name, for example a specific type and a　more generic type. In such cases, the sender of the TERMINAL-TYPE IS　command should reply to successive TERMINAL-TYPE SEND commands with　the various names, from most to least specific. In this way, a　telnet server that does not understand the first response can prompt　for alternatives. However, it should cease sending TERMINAL-TYPE　SEND commands after receiving the same response two consecutive　times. Similarly, a sender should indicate it has sent all available　names by repeating the last one sent.

　　Here are a few terminal types useful in the IBM environment:

　　IBM-3275-2

　　IBM-3276-2

　　IBM-3276-3

　　IBM-3276-4

　　IBM-3277-2

　　IBM-3278-2

　　IBM-3278-3

　　IBM-3278-4

　　RFC884December 1983

　　IBM-3278-5

　　IBM-3279-2

　　IBM-3279-3

　　Here are a few terminal types useful in the TOPS20 environment:

　　ANN-ARBOR-AMBASSADOR

　　CONCEPT-100

　　DATAMEDIA-2500

　　DEC-LA30

　　DEC-VT100

　　DEC-VT52

　　EXECUPORT-4000

　　HAZELTINE-1500

　　HP-2621

　　HP-2640

　　HP-2645A

　　HP-2649

　　NETWORK-VIRTUAL-TERMINAL

　　TEKTRONIX-4025

　　TELERAY-1061

　　TELETYPE-33

　　TELETYPE-37

　　TELEVIDEO-950

　　TERMINET-300

　　TI-700

　　ZENITH-H19

　　Here are a few terminal types used in the Unixenvironment:

　　ADDS-CONSUL-980

　　ADDS-REGENT-200

　　ANDERSON-JACOBSON-832

　　ANN-ARBOR-AMBASSADOR

　　BITGRAPH

　　CDI-1203

　　COMPUCOLOR-II

　　CONCEPT-100

　　DATA-GENERAL-6053

　　DATAGRAPHIX-132A

　　DATAMEDIA-3045A

　　DATAPOINT-3360

　　DEC-DECWRITER-II

　　DEC-GT40

　　DEC-VT52

　　DELTA-DATA-5000

　　DIABLO-1620

　　EXECUPORT-4000

　　RFC884December 1983

　　GENERAL-TERMINAL-100A

　　HAZELTINE-1500

　　HAZELTINE-2000

　　HP-2621

　　HP-2640A

　　HP-2645

　　HP-2649A

　　IBM-3101

　　INFOTON-100

　　LSI-ADM-3

　　MICROTERM-ACT-V

　　MICROTERM-MIME-2

　　NETWORK-VIRTUAL-TERMINAL

　　PERKIN-ELMER-1100

　　PLASMA-PANEL

　　SUPERBEE-III-M

　　TEKTRONIX-4014

　　TELERAY-3700

　　TELETYPE-33

　　TELETYPE-37

　　TELEVIDEO-912

　　TERMINET-300

　　TI-700

　　TI-733

　　TI-745

　　VISUAL-200

　　XEROX-1720

　　ZENITH-H19

　　ZENTEC-30

　　The type "UNKNOWN" should be used if the type of the terminal is　unknown or unlikely to be recognized by the other party.

　　The complete and up-to-date list will be maintained in the "Assigned　Numbers".