Request For Comments - RFC339
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NETWORK WORKING GROUP R.Thomas
REQUEST FOR COMMENTS #339 BBN
N.I.C. #9932 May 5,1972
MLTNET - A "MULTI-TELNET" SUBSYSTEM FOR TENEX
MLTNET is a TELNET-like facility for TENEX which enables a user to
control a number of jobs, running on different ARPANET hosts. It
multiplexes the user's local console among the remote jobs. MLTNET is
useful in applications which require coordinated behavior of several
network hosts. In particular, we have found it helpful in debugging
programs which make use of the network. The MLTNET program is designed
to be easy to use and, while used in remote mode, to be as transparent
as possible to the user. It is somewhat less sophisticated than the
TENEX user-TELNET program. MLTNET is currently a subsystem on the BBN-
MLTNET operates in two modes:
1. Local Mode Operation:
When in local mode MLTNET interprets input types by the
user as commands to it. Commands consist of a mnemonic
command name followed by zero or more parameters.
Included in the commands recognized by MLTNET are ones
which enable the user to associate a name of his choice
with a connection to an ARPANET site, to establish a
connection with a named site, to list the network status
as seen from the user's TENEX etc.
2. Remote Mode Operation
When operating in remote mode MLTNET makes the user's
console appear to be directly connected to a remote
site. It transmits input typed by the user to the
remote site and prints output recieved from the remote
site. Output received from a remote site while the user
is in local mode or is interacting with another remote
site is buffered for the user by MLTNET.
MLTNET has been designed to be transparent to the user
while operating in remote mode. In particular, when in
remote mode it transmits user-types ^C (CONTROL-C, the
TENEX "attention" character) and ^T (CONTROL-T, the
TENEX "time used query" character) to the remote site.
When in local mode ^C and ^T have their usual TENEX
Occasinally a user may find it necessary to modify the
characteristics of a connection to a particular remote
site. For example, he may want to have MLTNET echo
typed input as it is transmitted. Or, he may be using a
remote host which requires both upper and lower case
characters from a local terminal which has only upper
case; in such a case he would want MLTNET to transmit
upper and lower case as appropriate. In remote mode
operation MLTNET recognizes "!" as an escape character
and interprets the character following it as a command
to change the characterristics of the connection currently
in use. Commands recognized by MLTNET in remote mode
are summerized in the next section. To have MLTNET
transmit "!" to the remote site the user types "!!".
MLTNET Command Summary
Local Mode Commands
MLTNET uses the character "<" to signal the user that it is in local
mode ready to accept input. Commands and command parameters may be
editted as they are input.The character ^A (CONTROL-A) deletes the last
character input. In response to a ^A MLTNET types " deleted. The
character ^R (CONTROL-R) causes the input string as collected so far to
be retyped (with all editting carried out). MLTNET responds to the
character RUBOUT (octal 177) by aborting the current input collecting
operation and typeing the ready character "<". The ALTMODE character
(octal 175) may be used to invoke command recognition and completion. If
insufficient information is availble to recognize an input string as a
command MLTNET responds to ALTMODE by ringing the terminal bell. Any
prefix which uniquely identifies a command is recognized as that command
In the following, <name> and <site> denote command parameters. They are
strings terminated by a space or carriage return. <name> is a user
chosen string of 14 characters or less; site is either the name of an
ARPANET host or the string "LOCAL".
The commands recognized by MLTNET in local mode are:
syntax: ASSIGN <name> <site>
effect: Associates the user chosen string <name> with a
connection to the ARPANET site <site>.
syntax: TALK <name>
effect: Switches from command mode to remote mode
directing subsequent console input to the site
associated with <name>. If no ARPANET site is
currently associated with <name>, the user is
asked to spesify a site. The first time the
user "talks" to a particular named site MLTNET
goes through the ARPANET initial connection
protocol with the remote site in order to
establish a duplex connection with it.
effect: Prints on the console the <name>/<site>
associatins currently known to MLTNET.
effect: Returns control to the TENEX EXEC breaking all
connections with remote hosts. It is good
practice to log out of each remote host before
using the QUIT command.
effect: Prints on the console the network status as seen
from the local TENEX.
syntax: RENAME <name>1 <name>2
effect: Associates <name>2 with the ARPANET site
previously associated with <name>1.
syntax: FLUSH <name>
effect: Breaks the network connection with the ARPANET
site associated with <name> and, in addition,
breaks the association between <name> and that
effect: Prints on the console the list of hosts
currently known to the MLTNET subsystem.
effect: Prints on the console a breif summary of how to
Remote Mode Commands
In remote mode MLTNET recognizes the escape character "!" as a signal to
interpret the following character as a command. Currently MLTNET
recognizes the following characters as commands to it:
Q: (quit) Causes MLTNET to switch from remote mode to local
L: (local echo) Causes MLTNET to echo characters as it
transmits them to the remote site. ;L is the inverse of
R. The default case.
R: (remote echo) Causes MLTNET to transmit characters typed
to it without echoing them; invers of L.
U: (upper case) Causes MLTNET to transmit upper case letters
as typed; the inverse of S. The default case.
S: (small letters - lower case): Causes MLTNET to transmit
upper case letters typed to it as lower case letters.
In this mode of operation "^" acts as a shift key; "^"
may be transmitted by typing "!^". S is the inverse of
X: (where X is any character other than Q, L, R, U or S):
Causes MLTNET to transmit X.
The following is an annotated scenario which illustrates the use of
MLTNET; in it characters typed by the users are underlined.
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©2018 Martin Webb