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- User Documentation File for NOSHELL.COM V1.5
- Last Revised: 07-22-93
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- The program file, NOSHELL.COM, is hereby placed in the Public
- Domain by its author (me), Steve Dunn. This program has been tested
- extensively; nonetheless, there is no warranty of any kind, period. By
- using this program you agree to assume all risks associated with its use.
-
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- I would appreciate your feedback on this program at any time - you
- can best reach me via CompuServe electronic mail to ID 70034,2454.
-
- ---------------------------------------------------------------------
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- You should have received the following files, all of which were
- provided by the author:
-
- NOSHELL.COM - The main executable for COLOR monitors
-
- NOSHELLM.COM - The main executable for monochrome monitors If
- you plan to use this file, you MUST first rename
- it to be NOSHELL.COM; otherwise the CFG_NOSH.EXE
- utility will not work properly.
-
- CFG_NOSH.EXE - Allows changing the password for NOSHELL Note
- that the NOSHELL.COM file MUST be located in the
- same directory as CFG_NOSH.EXE, MUST be named as
- NOSHELL.COM, and that this MUST be the current
- default directory.
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- NOSHELL.DOC - This file of program documentation
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- NOTE: The initial password supplied is: 1234567890ABCDEF - please note
- that case IS significant, so you MUST match uppercase letters with
- uppercase letters!
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- --- Program Documentation For NOSHELL.COM - V1.5 ---
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- Using NOSHELL.COM
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- NOSHELL.COM is RAM-resident utility designed to enhance system
- security by requiring all users to enter a password before being allowed
- to execute a DOS shell from within any other program. This is useful in
- order to prevent an inexperienced user (or anybody else who lacks the
- proper password) from accessing DOS from (for example) Lotus 1-2-3 by
- using the /Worksheet System command.
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- NOSHELL.COM has been tested with (and works fine under) IBM PC
- DOS / MS DOS "COMMAND.COM", as well as "4DOS.COM" and the closely related
- Norton/Symantec version of 4DOS named "NDOS" operating systems. It does
- not function any other operating systems at this time (at least, I don't
- THINK it does).
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- NOSHELL.COM is not sensitive to the COMSPEC environment
- variable - nor to any other environment variable.
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- By itself, NOSHELL.COM does not offer any truly comprehensive
- PC system security - NOSHELL.COM is intended to be used in conjunction
- with *OTHER* software offering security features, such as the excellent
- hard disk menu system, "HDM-IV" (shareware written by Mr. Jim Hass of
- MicroFox).
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- The best way to activate NOSHELL.COM is to place this command
- in your AUTOEXEC.BAT file so that it is loaded each time your PC is
- booted. The syntax is simple - just use [d:][\path\]NOSHELL (no
- parameters are needed or accepted).
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- You can also load NOSHELL.COM from the DOS prompt at any time -
- just type [d:][\path\]NOSHELL <enter>. If you happen to own a copy of
- QEMM (the extended memory manager from Quarterdeck) or some similar memory
- management software, you should feel free to load NOSHELL.COM into the
- HIGH RAM area above 640K (it will work just fine, and will not use any of
- your lower RAM at all!). Otherwise, NOSHELL.COM will require
- approximately 2,224 bytes of lower RAM.
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- In the interests of keeping NOSHELL as small as possible, and of
- maximizing the degree of security provided, NOSHELL.COM *CANNOT*
- normally be uninstalled from RAM after it has been activated. To get rid
- of NOSHELL, you must re-boot your PC (after removing any reference to
- NOSHELL from your AUTOEXEC.BAT file). However, if you are using the
- TSRCOM utilities (or some equivalent software for managing RAM-Resident
- programs), NOSHELL.COM will respond as expected to the "MARK" and the
- "RELEASE" commands.
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- --- Program Documentation For NOSHELL.COM - V1.5 ---
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- Notes Regarding Passwords and NOSHELL.COM
- ---------------------------------------------------------------------
-
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- NOSHELL.COM uses a password which is between 6 and 16 keyboard
- characters in length. Any keyboard character is acceptable, but you
- should keep in mind that case *IS* significant. To NOSHELL, the word
- "password" is NOT the same as "Password". And, by close extension, the
- word "Password" is NOT the same as "Password " (note the extra trailing
- space!). If you wish, your system password can include blank spaces,
- numeric characters, etc - in any event, the maximum length of all
- characters in the password cannot exceed 16.
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- Whenever a DOS SHELL operation is requested, a small "window" will
- pop up over your screen display (if you are in a text display mode)
- requesting that enter the required password. If you do, the SHELL
- proceeds normally; if you don't, the SHELL request is aborted.
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- Note that the password you enter is NOT echoed to the screen in
- the interests of increased security (please type carefully, in other
- words!)
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- The pop-up window does NOT appear in non-text screen modes, but
- you will *STILL* need the password to proceed. Frankly, the wide variety
- in possible non-text screen modes makes it almost impossible to program a
- consistently accurate method of capturing part of the screen (and the
- memory requirements are usually prohibitive in any event).
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- --- Program Documentation For NOSHELL.COM - V1.5 ---
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- How does NOSHELL.COM work?
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- When first loaded, NOSHELL.COM re-directs the DOS INTERRUPT 21h
- system function call. Thereafter, when an INT 21h call is generated by
- any calling program, NOSHELL checks to see if the DOS EXEC request
- (service 04Bh of INT 21h) is being requested. If not, NOSHELL simply
- executes the normal INT 21h code.
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- If EXEC is being requested, NOSHELL then checks to see what
- filename is being EXECed. If the filename is "COMMAND.COM" (works for
- either IBM PC DOS or MS DOS) or "4DOS.COM" (the fine DOS SHELL program
- from J. P. Software which replaces "COMMAND.COM") or "NDOS.COM" (the
- Symantec version of 4DOS) then NOSHELL will execute its security routine
- and require a password before proceeding.
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- If the proper password is given, NOSHELL allows the EXEC to
- proceed. If not, it aborts the shell request by returning a DOS ERROR
- code 08 ("Insufficient Memory") to the CALLing program.
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- --- Program Documentation For NOSHELL.COM - V1.5 ---
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- Parting Words
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- Some programs use a DOS shell (i.e., use the DOS EXEC function
- with either COMMAND.COM, 4DOS.COM, or NDOS.COM) as part of their normal
- operation, and many DOS-based software packages which include their own
- "install" program also use DOS shells! You will probably want to unload
- NOSHELL.COM when you are installing new software on your hard disk
- (which is easy if you are using the TSRCOM utilities). Note that NOSHELL
- will help prevent unauthorized users from installing such software!
-
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- When you use CFG_NOSH.EXE, you will need to know the current
- NOSHELL[M] password (and remember, case IS significant!). The new password
- must be at least 6 characters long, and no more than 16 characters long.
- Any keyboard character, including blank spaces, can be used.
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- CFG_NOSH.EXE requires that NOSHELL.COM be in the current
- default directory - if it does not find the NOSHELL.COM program file,
- it will abort with an error message.
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- --- Program Documentation For NOSHELL.COM - V1.5 ---
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- Revision History:
-
- V1.0 - Released Jan, 1991
- V1.0A - Special Version, VERY limitted monochrome release (Jan, 1993)
- V1.1 -> V1.4 - None of these versions were ever released to the public;
- these version numbers were used exclusively for
- internal test purposes
- V1.5 - Released July, 1993
- [] Corrected problem with possible "hang" caused by Lotus 123 if
- the correct NOSHELL password was not given;
- [] Added the ability to detect Norton's NDOS as well as 4DOS and
- COMMAND.COM
-
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- ------------- [ END OF NOSHELL.COM V1.5 DOCUMENTATION ] -------------
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- --- Program Documentation For NOSHELL.COM - V1.5 ---