A Multi Telnet Subsystem for Tenex(1)

　　NETWORK WORKING GROUP R.Thomas

　　REQUEST FOR COMMENTS #339 BBN

　　N.I.C. #9932 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.

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　　When in local mode ^C and ^T have their usual TENEX　effect.

　　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.