Telnet Environment Option (RFC1408)
Original Publication Date: 1993-Jan-01
Included in the Prior Art Database: 2000-Sep-12
Internet Society Requests For Comment (RFCs)
D. Borman: AUTHOR [+2]
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.
Network Working Group D. Borman, Editor
Request for Comments: 1408 Cray Research, Inc.
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
2. Command Meanings
IAC WILL ENVIRON
The sender of this command is willing to send environment
IAC WONT ENVIRON
The sender of this command refuses to send environment variables.
IAC DO ENVIRON
The sender of this command is willing to receive environment
IAC DONT ENVIRON
The sender of this command refuses to accept environment
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
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, USERV...