NETWORK WORKING GROUP
REQUEST FOR COMMENTS #339
N.I.C. #9932

R.Thomas
BBN
May 5,1972

MLTNET - A "MULTI-TELNET" SUBSYSTEM FOR TENEX

INTRODUCTION

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- TENEX host.

USING MLTNET

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.

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 by MLTNET.

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:

ASSIGN:

syntax: ASSIGN <name> <site>

effect: Associates the user chosen string <name> with a

connection to the ARPANET site <site>.

NAMES:

syntax: NAMES
effect: Prints on the console the <name>/<site>

associatins currently known to MLTNET.

QUIT:

syntax: QUIT
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.

NETSTAT:

syntax: NETSTAT
effect: Prints on the console the network status as seen

from the local TENEX.

RENAME:

syntax: RENAME <name>1 <name>2 effect: Associates <name>2 with the ARPANET site

previously associated with <name>1.

FLUSH:

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 site.

HOSTS:

syntax: HOSTS
effect: Prints on the console the list of hosts

currently known to the MLTNET subsystem.

HELP:

syntax: HELP

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

mode.

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
        U.