Contents of the XSNOOP.DOC file
XSNOOP 1.0 Security Utility
XSNOOP is a security program designed to discourage people from
snooping in your personal computer. XSNOOP is based on a simple idea:
because virtually any PC security program can be beaten by a deter-
mined snooper, the most effective security program is one that doesn't
*look* like a security program. XSNOOP is designed to look like DOS
itself, giving snoopers the impression that they are dealing with a
balky operating system rather than a security program.
When you activate XSNOOP, it replaces your DOS prompt with a sim-
ulated prompt. The simulated prompt "looks and feels" like the DOS
prompt, and it allows a user to enter commands just like the DOS
prompt does. Unlike the DOS prompt, however, the simulated prompt
created by XSNOOP discards commands instead of processing them. If
you wish, the simulated prompt will respond to snoopers' commands by
displaying one of several standard DOS error messages, like "Memory
allocation error" or "EXEC error". Hopefully, when a snooper sees
what looks like the DOS prompt and what look like DOS error messages,
he will not realize that he has come up against a security program at
all and therefore will not try to get around the program. The only
way to terminate XSNOOP and restore the DOS prompt is to enter a pri-
vate password that you specify when you activate XSNOOP.
XSNOOP can be run from DOS any time you are going to be away from
your computer. In addition, XSNOOP can be added to your AUTOEXEC.BAT
file, creating an invisible password logon feature when your computer
is turned on.
1. Trying Out XSNOOP: An Introduction
Although XSNOOP can be used with floppy disks, it is designed for
use on a hard disk system. Begin by copying the XSNOOP program file
(XSNOOP.EXE) to your hard disk. The program file should be in a
directory that is covered by your PATH command, so you can activate
XSNOOP from anywhere on your hard disk.
Before you use XSNOOP, select a private password. The password
can be any continuous string of characters and can be up to 20 charac-
ters long. The following are examples of valid passwords:
To try out XSNOOP the first time, enter "xsnoop -password /c/m1"
at the DOS prompt, where "password" is the private password you have
selected for yourself. For example, if your password is "avocado",
enter "xsnoop -avocado /c/m1" at the DOS prompt. The password must be
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preceded by the "-" character, which tells XSNOOP that your password
is coming next. The switches ("/c/m1") invoke XSNOOP options which
are explained below.
When you enter this command, your screen will clear and XSNOOP's
simulated prompt will appear at the top of the screen. Now try enter-
ing a DOS command, like "dir" or "del *.bak". The command will not be
processed. Instead, XSNOOP will display a standard DOS error message
("Bad command or file name") and the simulated prompt will reappear.
Each time you enter a command, the same error message will appear and
the simulated prompt will reappear. What you are seeing on the screen
-- a DOS prompt that does not process commands and a repeated DOS
error message -- is the same thing you might see if something were
wrong with your hard disk or DOS.
To terminate XSNOOP and restore the real DOS prompt, enter your
password at the simulated prompt. Do *NOT* precede the password with
the "-" character that you used when you started XSNOOP. For example,
if your password is "shortstop", enter "shortstop" at the simulated
prompt, not "-shortstop". The screen will clear again and the real
DOS prompt will reappear. None of the commands that you entered at
the simulated prompt has been processed and none has had any effect on
2. XSNOOP's Options
XSNOOP has a variety of options that allow you to customize the
program's appearance and operation. XSNOOP's full syntax is:
XSNOOP -password [/c] [/l] [/m1.../m6] [/s]
As you already know, "-password" specifies the password that must
be entered at XSNOOP's simulated prompt in order to terminate XSNOOP
and restore the real DOS prompt. The switches specify the options
that XSNOOP allows you to select. You must include a password when
you invoke XSNOOP, but each of the switches is optional. The meaning
of the switches is as follows:
2.1. Console display cleared (/c)
By default, XSNOOP does not clear the screen when it starts.
When "/c" is added, XSNOOP clears the screen before it presents the
simulated prompt. This allows you to "erase" the command line that
2.2. Long prompt created (/l)
By default, XSNOOP uses the standard DOS prompt (for example,
"C>"). Many people use DOS's PROMPT command to add the current direc-
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tory path to their prompt, so that when (for example) the current
directory is C:\123\FILES, the prompt is "C:\123\FILES>". When "/l"
is added, XSNOOP's simulated prompt duplicates this long DOS prompt,
adding extra realism to the display.
2.3. Message displayed (/m1-/m6)
By default, XSNOOP does not display an error message when a com-
mand is entered at the simulated prompt. If you wish, however, XSNOOP
can display any one of six error messages. The messages are:
/m1 = "Bad command or file name"
/m2 = "Insufficient memory"
/m3 = "Memory allocation error"
/m4 = "EXEC failure"
/m5 = "General Failure"
/m6 = "Internal Stack Error, System Halted"
Each of these commands is a standard DOS error message. Having
XSNOOP generate one of these error messages will enhance the illusion
that XSNOOP tries to create -- namely, that the snooper is being
stymied by a balky operating system rather than by a security program.
It is therefore recommended that you have XSNOOP invoke one of these
error messages each time you run XSNOOP.
Note that only one error message may be specified when you run
XSNOOP. If you add more than one error message switch on the command
line (for example, "xsnoop /m1/m3"), XSNOOP will abort.
2.4. Speaker beeped (/s)
By default, XSNOOP is a silent program. However, in addition to
displaying an error message, XSNOOP can beep your speaker each time a
command is entered. Adding "/s" turns on the speaker feature.
3. Using XSNOOP Regularly
XSNOOP is available both when you are using your computer and
when you are not. To run XSNOOP when you are using your computer,
simply invoke XSNOOP from the DOS command line. If you are using an
application program that allows you to "shell to DOS", like WordPer-
fect or Lotus 1-2-3, you can shell to DOS and invoke XSNOOP without
exiting your application. When you return to your computer, simply
enter your password and XSNOOP will return control to DOS.
If you ordinarily use the same password and options, you can make
life easier for yourself by creating a simple batch file that includes
the password and command line switches. For example, if your password
is "jabberwocky" and you want XSNOOP to clear the screen and display
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error message 4 (""EXEC failure"), create a batch file called XS.BAT
(or any other legal name) that contains the following lines:
xsnoop -jabberwocky /c/m4
In this example, each time you enter XS at the command line, XSNOOP
will be executed with the /c and /m4 options.
To have XSNOOP "on guard" when your computer is off, simply add
XSNOOP (with your password and option switches) to your AUTOEXEC.BAT
file. Adding XSNOOP to AUTOEXEC.BAT turns XSNOOP into an invisible
password logon program: each time your computer is turned on, your
password must be entered at the simulated prompt before the computer
can be accessed. Because XSNOOP simulates the DOS prompt, someone who
turns your computer on before you arrive at work will not (hopefully)
realize that he's being turned away by a security program. Adding
XSNOOP to AUTOEXEC.BAT also provides added security when your computer
is already running: if a snooper tries to "break in" by rebooting your
computer while the computer is one and you're away, AUTOEXEC.BAT will
reload XSNOOP and the security will remain in effect.
XSNOOP is not unbeatable. If someone is determined to get into
your computer and he has the time and the expertise, he can do so
easily. Even if you've activated XSNOOP and added it to your AUTO-
EXEC.BAT file, a snooper who knows what he's doing and knows what he's
up against can defeat it by putting a bootable diskette in drive A and
rebooting your computer. XSNOOP is designed to discourage snoopers,
but there is no guarantee that a determined snooper will be kept out.
If you forget XSNOOP's syntax, you can get help by executing
XSNOOP: (1) without any arguments ("xsnoop"); or (2) with any argument
that is NOT a valid switch (like "xsnoop ?" or "xsnoop help", or even
"xsnoop rhubarb"). XSNOOP will display a small help screen that lists
XSNOOP's syntax and the meaning of XSNOOP's option switches.
6. Terms of Distribution
XSNOOP is a shareware program. You may try XSNOOP without charge
for one month to see if it suits your needs. You may not use XSNOOP
for more than one month without registering the program. To register,
please send $10 to:
3500 Taylor Street
Chevy Chase, MD 20815
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You are free to distribute XSNOOP to other people. You may not
charge for XSNOOP or alter XSNOOP's executable code. If you distrib-
ute XSNOOP, please include the original documentation files
(XSNOOP.DOC and READ.ME) along with the program file (XSNOOP.EXE).
XSNOOP is provided "AS IS", without any promises or warranties of
any kind, express or implied. In particular, XSNOOP IS NOT GUARANTEED
TO PREVENT OTHER PERSONS FROM USING YOUR COMPUTER. If you use XSNOOP,
you assume exclusive responsibility and liability for any loss or
damage directly or indirectly arising out of the use of the program.
7. Questions, Suggestions, and Bug Reports
Questions, suggestions, and bug reports are welcome. I can be
reached by mail at the address above or by e-mail at the following
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