Making an Antivirus Bootdisk for FAT16 & FAT32 Partitions

Overview: As part of your PC servicing toolkit you must always have an up-to-date Antivirus bootdisk.  This will enable you to test any PC with FAT16 and FAT32 partitions for viruses before installing Antivirus software.  This practical will require some knowledge of batch file programming and incorporate the use of compression software.

Aim: To make an Antivirus bootdisk that will automatically scan all partitions (FAT16 & FAT32) for viruses on a PC.  Using the options available by the antivirus program you will configure the scan to automatically clean any viruses that are found on all of the PC’s partitions.  The ideal bootdisk will contain up-to-date virus definition files, scan both FAT 16 and FAT 32 partitions and automatically clean any viruses found.  Your bootdisk must retain the option for CDROM support offered by the Win 98 bootdisk.

Resources: VET antivirus software program with virus definition file updates, PC with FAT 16 and FAT 32 partitions and Windows 98 operating system, three spare HD floppy disks, CABPACK Software program for CABINET file manipulation.

Download the CABPACK now!  Note: This is a zip file.  You need to extract these files using "Winzip" or another program that knows how to decompress/extract ".zip" files.

Procedure:

            Step 1. Install antivirus software provided by the teacher on the Windows 98 PC.  Install any “updates” available. Make the antivirus program rescue disks after rebooting.  These are PC specific!  Therefore they will not represent the bootdisk you are to configure!

            Step 2. Make a Windows 98 bootdisk using the following method: Using the Windows 98 operating system - Go to “Control Panel” and double-click on “Add/Remove Programs”.  Choose the “Startup Disk” TAB from the next window.  Click on the “Create Disk” button and follow the prompts to create your “Win 98 bootdisk”.

            Step 3. Unzip the CABPACK file from "cab.zip" to a folder named "cabpack".  Make two more folders named "temp1" and "temp2". 

Step 4. Bootup the PC using the Win 98 bootdisk you just created and copy all the files on the RAMDRIVE to the “temp1” directory you created on the HDD.  Delete “command.com” and “extract.exe” from the “temp1” directory.

Step 5. Delete the file named “Ebd.cab” from your Win 98 bootdisk.  Record the amount of space left on your bootdisk in the ‘Results’ space provided below in (1).

Step 6. TABLE 1 contains a list of all the files you may require to perform an antivirus scan on a PC when run from a bootdisk (This includes antivirus files and Win 98 files such as fdisk.exe!).  Copy all the files listed in TABLE1 to the “temp1” directory that you previously created on the HDD (you may add other files if you like).

Step 7. You will find that you do not need all the device drivers that are loaded by the Win98 startup disk.  In fact, if you think about it, you only really need THREE (himem.sys, Ebd.sys and the CDROM device driver – oakcdrom.sys).  Therfore, you can delete all the unnecessary files from your Win 98 bootdisk.  Record the cleanup results below in number (2).  Note: If you delete the real mode device drivers (they generally end with the “.sys” file extension) you must edit (comment out) the device drivers that you deleted under the [CD] menu heading.  For a complete list of device drivers loaded by “config.sys” see the file named “readme.txt” on the Win98 startup disk.

Step 8. Now start your "CABPACK.EXE" program and compress all the Antivirus files and tools files you require into a file named "EBD.CAB".  You can PATH this file into the "Temp2" folder that you created previously in 'Step 3'.  This is not a hard task! 

Record the size of the compressed file named “Ebd.cab” in the results below (3).

Step 9. Compare the space available on the floppy disk with the size of the file named “Ebd.cab”.  If the file is small enough to copy to the floppy disk, then do so.   If not, you must make another “Ebd.cab” file using the same steps that were outlined above.  (Don’t forget – your bootdisk must have the option for CDROM support).

                Step 10. After copying the “Ebd.cab” file to your bootdisk you may have to edit your “config.sys”, “autoexec.bat” files and/or make another batch file to ensure that your antivirus scan runs automatically (and with correct options).

                Now test your Win 98 startup disk to make sure it boots up correctly.  Now type the following command:

                                rescue.exe /?

                You should now be viewing the list of scanning options available to you.  Think about the options you may want and record the necessary switch commands you require.  Record the full rescue command that you chose to use in number (4) below.  The command will obviously start with “rescue”!  Now put the command at the END of  your startup disk’s “Autoexec.bat” file! (e.g. rescue.exe c:\*.* /e /f /r)

Another hint: You can edit the Win 98 menu selection time-out (default = 30 secs) by changing its value in “Autoexec.bat”.  You may want to experiment with the menu colour by changing the default menu color numbers.  You can also comment out the fourteenth line if you delete readme.txt from the root directory of the Win 98 startup disk (i.e. “copy readme.txt %RAMD%:\ > NUL”).

Step 11. Submit your bootdisk so that the teacher can verify your results.

Step 12. Answer the questions below regarding the practical you have just completed.

Step 13. If time permits, change computers and try this exercise with a different type of antivirus program (InoculateIt, Norton and McAfee are available).

Results:

1.         Space left on floppy bootdisk after deletion of “Ebd.cab”:

             ______________________

2.         Space left on bootdisk after deletion of device drivers & other files: 

             ______________

3.         Size of compressed “Ebd.cab” file in “temp2” folder. 

             _________________________

4.         Full scanning command chosen (i.e. rescue.exe plus switches).  

            __________________

Questions:

1.         When are you likely to change the configuration of your antivirus bootdisk?

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2.         Why would you make sure “fdisk.exe” is on your antivirus bootdisk?

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3.         If all the antivirus definition files would not fit on your bootdisk even after compression, how could you configure the second part of your bootdisk and what changes to “autoexec.bat” and “config.sys” would you make?

            _____________________________________________________________________

 

4.         If you are desperate for space, you can achieve some very small gains in floppy disk space.  Name of few of the desperate measures you would take.

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