Telnet Environment Option (RFC1408)
Original Publication Date: 1993-Jan-01
Included in the Prior Art Database: 2019-Feb-10
Internet Society Requests For Comment (RFCs)
This document specifies a mechanism for passing environment information between a telnet client and server. [STANDARDS-TRACK]
Network Working Group D. Borman, Editor Request for Comments: 1408 Cray Research, Inc. January 1993
Telnet Environment Option
Status of this Memo
This RFC specifies an IAB standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "IAB Official Protocol Standards" for the standardization state and status of this protocol. Distribution of this memo is unlimited.
This document specifies a mechanism for passing environment information between a telnet client and server. Use of this mechanism enables a telnet user to propagate configuration information to a remote host when connecting.
1. Command Names and Codes
ENVIRON 36 IS 0 SEND 1 INFO 2
VAR 0 VALUE 1 ESC 2 USERVAR 3
2. Command Meanings
IAC WILL ENVIRON
The sender of this command is willing to send environment variables.
IAC WONT ENVIRON
The sender of this command refuses to send environment variables.
Telnet Working Group [Page 1]
RFC 1408 Telnet Environment Option January 1993
IAC DO ENVIRON
The sender of this command is willing to receive environment variables.
IAC DONT ENVIRON
The sender of this command refuses to accept environment variables.
IAC SB ENVIRON SEND [ type ... [ type ... [ ... ] ] ] IAC SE
The sender of this command requests that the remote side send its environment variables. The "type" may be either VAR or USERVAR, to indicate either well known or user variable names. Only the side that is DO ENVIRON may initiate a SEND command. If a list of variables is specified, then only those variables should be sent. If no list is specified, then the default environment, of both well known and user defined variables, should be sent. If one of the variables has no name, then all the variables of that type (well known or user defined) in the default environment should be sent.
IAC SB ENVIRON IS type ... [ VALUE ... ] [ type ... [ VALUE ... ] [
The sender of this command is sending environment variables. This command is sent in response to a SEND request. Only the side that is WILL ENVIRON may send an IS command. The "type"/VALUE pairs must be returned in the same order as the SEND request specified them, and there must be a response for each "type ..." explicitly requested. The "type" will be VAR or USERVAR. Multiple environment variables may be sent. The characters following a "type" up to the next "type" or VALUE specify the variable name. The characters following a VALUE up to the next "type" specify the value of the variable. If a "type" is not followed by a VALUE (e.g., by another VAR, USERVAR, or IAC SE) then that variable is undefined. If a VALUE is immediately followed by a "type" or IAC, then the variable is defined, but has no value. If an IAC is contained between the IS and the IAC SE, it must be sent as IAC IAC. If a variable or a value contains a VAR, it must be sent as ESC VAR.
If a variable or a value contains a USERVAR, it must be sent as ESC USERVAR. If a variable or...