Columbia Kermit/kermit.zip/hostmode/hostuser.txt

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KERMIT 95 HOST MODE USER'S GUIDE

  ---   PREPUBLICATION DRAFT   ---

  Copyright (C) 1996, Frank da Cruz and Christine M. Gianone.
  All rights reserved.

Most recent update: February 8, 1996.

Applies to:
  Kermit 95 1.1.3,
  Host Mode script version 1.00,
  Windows 95 and NT.

CONTENTS

  1. GETTING CONNECTED
  2. LOGGING IN
  3. THE HOST MENU
  4. DIRECTORIES
  5. COMMANDS
  6. CD PRIVILEGE
  7. DOS PRIVILEGE
  8. POSTSCRIPT: WHY CAN'T I HAVE AN INTERACTIVE REMOTE DOS SESSION?

INTRODUCTION

Kermit 95 host mode is like a mini BBS running on a Windows 95 or Windows NT
system that you can connect to using your communication software so you can:

 . Upload and download files using Kermit, ZMODEM, or other protocols
 . Receive messages from and leave messages for the PC owner
 . Execute certain types of DOS commands

Real Kermit software is recommended: Kermit 95, MS-DOS Kermit, OS/2 C-Kermit,
UNIX C-Kermit, etc:

 . VT100 or ANSI emulation is required
 . Kermit file transfer protocol is recommended
 . Kermit server mode is required when Kermit protocol is selected
 . "set terminal apc on" is recommended for automatic up- and downloads
 . "set server display on" is recommended so you can monitor uploads
 . "set term byte 8" and "set term char cp437" recommended
 . A scrollback feature is needed on certain occasions

The Kermit 95 host is a PC running Windows 95 or NT and Kermit 95 in "host
mode".  A username and password must have been set up for you in advance by
the owner of the PC (the "proprietor") or else the proprietor must have
configured the Kermit 95 host to allow anonymous logins, in which case you
can use "guest" as the username, and supply anything at all as your
password.

1. GETTING CONNECTED

You can make either a dialup or a Telnet connection to a Kermit 95 host,
depending on how the proprietor set it up.  To make a dialup connection,
simply dial the number given to you by the proprietor and then enter your
terminal emulator, for example (in Kermit-95, MS-DOS Kermit, or C-Kermit):

  set terminal apc on
  dial 5551234
  connect

NOTE: "apc" is the VTxxx Application Program Command escape sequence which
is recognized by Kermit 95, MS-DOS Kermit, and C-Kermit.  It is this feature
that allows host mode to initiate uploads and downloads automatically
without you having to "escape back" and give commands to your local Kermit
program.  Read about APC in the KERMIT.UPD or CKERMIT.UPD file that comes
with your Kermit software.

As with all dialup connections, make sure you have an adequate method of
flow control (preferable RTS/CTS hardware flow control) enabled, or else
characters are very likely to be lost in both directions.

To make a Telnet connection, tell your Kermit client software to "telnet
<hostname> <socket-number>".  The <hostname> is the TCP/IP hostname of the
proprietor's PC, and the <socket-number> is a number, usually 3000, given to
you by the proprietor.  So, assuming that host mode is running on a PC whose
IP hostname is pc.oofa.com, and it is listening for a connection on TCP port
3000, you would connect to by giving the following commands to your own Kermit
software:

  set terminal apc on
  telnet pc.oofa.com 3000

2. LOGGING IN

When you first connect to Kermit 95 host mode, the screen contains:

  K-95 Login

  Username: _

Type your username, using the backspace key for editing if necessary, and then
press the Enter or Return key.  Then the Password: prompt appears.  As you
type your password, each character is echoed as an asterisk (*).

  NOTE: On a Telnet connection, if characters are echoing twice on your
  screen, return to your terminal program and instruct it to disable local
  echoing.  (In most cases this should not be necessary.)

If the username / password combination is not valid, the message "Access
denied" is displayed and you get two more chances to log in.  If you fail to
log in successfully after three tries, the connection is closed and hung up.

3. THE HOST MENU

After a successful login, you might see a greeting or news message from the PC
owner.  After reading these texts, you are prompted to "Press any key to
continue" and after you do so, you are placed in your personal directory and
the main menu appears:

                   Welcome to K-95 Host Mode

                   Current directory: D:/K95/USERS/OLGA
                   Protocol: Kermit, Transfer mode: binary

                   Choices:

                    1 - Change protocol
                    2 - Change transfer mode
                    3 - Change directory
                    4 - List files
                    5 - Download files
                    6 - Upload files
                    7 - View a file
                    8 - Delete files
                    9 - Read messages
                   10 - Leave a message
                   11 - Change password
                   12 - Help
                   13 - Logout
               (*) 14 - Execute a DOS command

                   Enter choice: _

                   Last command: OK

(*) Item 14 appears only if your user ID has been equipped with the
    necessary privilege.

The "Last command" line tells whether your most recent command succeeded
or failed.

If anonymous logins are permitted, guest users are placed in the PUBLIC
directory.  Guest logins do not have a personal directory.

4. DIRECTORIES

Each user has access to three directories:

 1. Your own personal directory.  This directory has the same name as your
    username.  You may upload to and download from this directory.  Other
    host-mode users do not have access to your personal directory.
    (Anonymous GUEST logins have no personal directory.)

 2. The PUBLIC directory.  All host-mode users may download files from this
    directory, but may not upload to it or modify it in any other way.
    This directory is used by the PC owner for distributing files to users.

 3. The INCOMING directory.  All host-mode users may upload files to this
    directory.  Thus, different users can share files through this directory
    without intervention from the PC owner.

In addition, privileged users can also access other directories; see the
section on CD PRIVILEGES below.

5. COMMANDS

The menu choices are as follows.  To choose a menu item, enter its number and
then press the Enter or Return key.

1 - Change protocol

    The current file transfer protocol is shown on the main screen, just
    above the menu.  This menu option lets you change it.  The choices are
    Kermit, ZMODEM, YMODEM, YMODEM-G, and XMODEM.  Make sure your client
    software is set up to use the same protocol.

2 - Change transfer mode

    The current default transfer mode, text or binary, is shown above the
    menu.  Use this option to change it.

3 - Change directory

    Displays a menu with the choices "Your own home directory", "The PUBLIC
    directory", and "The INCOMING directory", and allows you to choose one,
    or to return to the main menu without changing anything.

4 - List files

    Displays a listing of the current directory on your screen.  If the
    listing is longer than your screen, naturally, it scrolls off the top.
    The presumption is that your client software has a scrollback feature.
    At the end of the file, your are instructed to "Press any key to
    continue", at which point the file disappears and the main menu comes
    back (but even after this happens you should still be able to scroll
    back to the directory listing).

5 - Download a file

    Prompts you for a filename.  If the file exists in the current PC host
    directory, it is sent to you in the current transfer mode using the
    current protocol.  The transfer happens automatically if the protocol is
    Kermit and your client program supports Kermit's APC mechanism and has
    it enabled, OR if your client program supports Kermit or ZMODEM
    automatic downloading (as Kermit 95 does).  Otherwise you will see a
    message instructing you to start your end of the transfer, which you
    should do using whatever method is required by your terminal program.

2 - Upload a file

    Works only if the current directory is your own private directory or the
    INCOMING directory.  Prompts you for a filename.  If the file exists and
    is accessible on your computer, it is sent using the current protocol
    and whatever transfer mode, text or binary, you your client software is
    set up for.

    The transfer happens automatically if the protocol is Kermit and your
    client program supports Kermit's APC mechanism and has it enabled AND if
    your client program can enter Kermit server mode.  Otherwise you will
    see a message instructing you to start your end of the transfer.  If the
    file is sent containing a pathname, the pathname is stripped to ensure
    that the file is stored in the host PC's current directory and not
    somewhere else.

7 - View a file

    Prompts you for a filename.  If the file exists in the current directory
    and is readable, it is displayed on your screen in the same manner as a
    directory listing.  Use scrollback, if necessary, to view any portions
    that scrolled off the screen.

8 - Delete a file

    Deletes a file on the Kermit 95 host PC.  This is permitted only in
    your own private directory.  Prompts you for the filename.

9 - Read messages

    If you have one or more messages from the PC owner, the main menu says
    "Message(s) waiting...".  Use this menu option to read them.  After
    reading, you can keep, delete, move, or download the messages.

10 - Leave a message

    Leave a message for the proprietor (sorry, there is presently no way to
    send a message to another user).  The message is automatically
    timestamped and your username is shown as the sender.  You are prompted
    for a subject.  Then may type zero or more lines of text as the message
    body.  To include a blank line, for example between paragraphs, type at
    least one space.  When you are finished, enter a period (.) alone on a
    line.  At that point, you can choose whether to send or cancel the
    message.  If you choose to send it, it is sent to the proprietor's
    message file and a message appears immediately on the proprietor's screen
    announcing that you have sent a message, and listing its subject.  So
    sending a message with only a subject and no body is a handy way to get
    the proprietor's attention (if s/he is sitting at the host PC).

11 - Change password

    Use this option to change your password.  You are prompted for your old
    password as a safety precaution.  If you enter it correctly, then you
    are prompted for the new password, and then you are asked to enter it
    again to guard against typing errors.

12 - Help

    Displays a brief help text.

13 - Logout

    Logs you out from host mode and hangs up the connection.

14 - Execute a DOS command

    This option is available only to users who have been granted this
    privilege by the proprietor, as it allows more or less unrestricted
    access to the proprietor's PC.  If you do not have DOS privilege, this
    item does not appear on the menu.  See section on PRIVILEGES below.

In any dialog, as when you are being prompted for a menu item or a filename,
the following special characters can be used for editing and control:

    Backspace - Erase the rightmost character
    Delete    - Erase the rightmost character
    Ctrl-H    - Erase the rightmost character
    Ctrl-U    - Erase all the characters typed so far, back to the prompt
    Ctrl-C    - Return immediately to the main menu
    Ctrl-L    - Refresh the screen

Ctrl-C cannot be used during the login dialog.

6. CD PRIVILEGE

If the proprietor has granted you "CD Privilege", this allows you to change
your current directory (CD) to any directory on the PC and therefore to
upload and download files to/from any directory, to delete files in any
directory, and to view the contents of any directory.  If you have CD
Privilege, you will see an item 4 in the Change Directory menu:

      Choices:

      1 - My home directory (read/write only by me)
      2 - The PUBLIC directory (everybody can read it)
      3 - The INCOMING directory (everybody can write)
      4 - A specific directory
      5 - Return to main menu

If you don't have CD Privilege, item 4 does not appear and you are
restricted to your personal directory plus the PUBLIC and INCOMING
directories.

7. DOS PRIVILEGE

DOS privilege allows you to execute DOS commands.  DOS privilege also
implicitly includes CD privilege, since you can refer to any disk or
directory in a DOS command.  If you have DOS privilege, item 14 - "Execute a
COS command" appears in the main menu.

This menu choice does not give you a DOS prompt.  Rather, it lets you send a
command to the K95 host to be passed to DOS for execution in the context of
your current directory.  The K95 host does not and can not enforce any kinds
of restrictions or safety measures on these commands.

You should only enter DOS commands that:

 1. Require absolutely no input from the PC keyboard or mouse.

 2. Write their output in text mode on the DOS screen and then
    exit immediately.

If you enter a DOS command that might possibly require input from the PC
keyboard (example: a COPY command might result in "Overwrite <existing file
(Yes/No/All)?") or a command that starts a GUI program, or a command that
starts an interactive program such as a text editor, your session will
become stuck and you will have to hang up.  This is a limitation of DOS;
input cannot be redirected reliably, and output can be redirected only if it
is the "standard output" of a text-mode DOS program or command.

Your DOS command may be entered in the normal way without the output
redirection symbol (">"), in which case the command's output is displayed on
your screen; if the output scrolls off the top of your screen, use the
scrollback feature of your terminal program to view the earlier material.

If your DOS command includes the ">" symbol to redirect the command's output
to a file, then you can use the Download or View options from the main menu
to download or view the resulting file afterwards.

Examples of unsafe DOS commands (not a complete list):

  time       (because it prompts for a new time)
  date       (because it prompts for a new date)
  copy       (because it might prompt for permission to overwrite a file)
  delete     (because it might prompt "Are you sure (Y/N)?")
  dir /p     (because it prompts "Press any key to continue")
  more       (because it prompts "-- More --")
  move       (because it might prompt for permission to overwrite a file)
  deltree    (because it prompts for permission to proceed)
  chkdsk     (because it might prompt for permission to fix a disk)
  qbasic     (because it is an interactive program)
  edit       (because it is an interactive program)
  help       (because it is an interactive program)
  notepad    (because it is an interactive program and a GUI program)

Plus any command at all that might reference a disk that is not ready,
resulting in the familiar "Abort, Retry, Fail?" prompt.

Examples of safe DOS commands (assuming they do not reference a disk that
is not ready, and not a complete list, and with no guarantees):

  echo
  fc
  find
  mem
  rename
  dir        (without /P, but possibly with other switches)
  mkdir
  rmdir
  set
  copy /Y    (suppresses prompt)
  move /Y    (suppresses prompt)
  deltree /Y (suppresses prompt)
  start      (without /W switch)
  xxx /?     (prints help text for DOS command xxx)

Plus any command that starts a DOS text-mode program that meets the "safe"
requirements given above.  For example, many of the GNU UNIX utilities like
grep, wc, etc, that have been ported to Windows 95 and NT, or (in most cases)
the Microsoft "nmake" or "cl" programs that are used for compiling C
programs, and probably other compilers too, at least when invoked with the
appropriate command-line options (example: the Microsoft Help compiler will
run without requiring any interaction when given the /E and /C switches).

NOTES:

 1. The "Last command" status for DOS commands will not necessarily be
    correct, since DOS does not accurately report the status back to the
    Kermit 95 host.

 2. If you make a mistake in a DOS command, the error message is not
    displayed for you.  Instead, it comes out on the host PC's screen.
    That's another DOS feature.  Similarly if a command is entered correctly,
    but fails; for example, "rmdir oofa" will fail if the "oofa" directory is
    not empty, but you won't see the error message.

 3. CD, when given as a DOS command with arguments, has no effect.  To change
    disks or directories, use the "Change directory" item in the main menu.


8. POSTSCRIPT: WHY CAN'T I HAVE AN INTERACTIVE REMOTE DOS SESSION?

Unlike multiuser operating systems such as UNIX and VMS, Windows and DOS
were not designed to be used remotely.  The DOS/Windows user is expected to
be sitting at the PC, looking at the PC's monitor, and controlling the PC
physically with the keyboard, mouse, and possibly other input devices.

Many DOS commands REQUIRE input from the PC's physical keyboard or mouse,
and the input source can not be redirected.  Even if they could be,
PC-specific keys or combinations that are required in certain situations,
such as F-keys, Alt-key combinations, arrow and editing keys, etc, can not
be represented by ordinary characters such as sent by a terminal or Telnet
program.

In the other direction, output is not always the simple writing of text to
"standard output", but often involves manipulation of internal video buffers,
calls to the graphical shell, or otherwise non-redirectable writes to the PC
console (screen, speaker, etc).  All of this is in contrast to text-based
operating systems like UNIX or VMS, which are designed from the beginning to
allow sessions to come from anywhere and to be redirected in any desired
manner.

Gaining the commonly-desired sort of remote access to a Windows-based PC
("I want to use my work PC from my home PC, just as if I was at work")
requires not a Telnet server or a "host mode", but rather an elaborate
special-purpose Windows-specific "remote access" product that traps key
events, mouse actions, video-buffer manipulations, etc, and which necessarily
restricts access to only Windows-based clients, or clients that can emulate
the Windows environment.  Remote access products for Windows 95 and NT cost
in $150-200 range, require lots of disk space, and you need one (generally
the SAME one) for each end.  Furthermore the host PC can only support one
remote access session at a time, so if you want multiple clients to access
your PC-based services simultaneously, you'll need multiple host PCs.
Examples of remote access products include LapLink for Windows 95,
pcAnywhere-32, and Remotely Possible/32.

Kermit 95's host mode grants a more limited type of access, but to a much
wider variety of clients -- any computer that can run a simple VT100 or ANSI
terminal emulation program: a DOS PC, a UNIX workstation, a Macintosh, an
Apple II, a central computer running UNIX, VMS, VOS, or AOS/VS, and so on,
and multiple host sessions can be active simultaneously on a single PC.
Therefore Kermit 95's host mode is a good approach for PC owners who need to
provide remote access to a diverse assortment of clients with a minimum of
overhead, for the primary purpose of downloading and/or uploading of files
within a secure framework, rather than for letting remote users run
Windows-based applications.

If your needs exceed Kermit 95's range of services, you should investigate
either a remote access product, which makes a "Windows clone" of your system
for one client at a time, or a full-fledged BBS system that provides a wider
range of services, usually restricted to text mode, to a potentially large
number of simultaneous users, generally at rather high cost.

(End of HOSTUSER.DOC)