Using System Policies to Hide Specific Drive Letters (220955)

MORE INFORMATION

Using the Common.adm Files Included with Windows NT

This policy shows only specified drives on the client computer. The registry key that this policy affects uses a decimal number that corresponds to a 26-bit binary string, with each bit representing a drive letter:

   11111111111111111111111111
   ZYXWVUTSRQPONMLKJIHGFEDCBA
				

This configuration corresponds to 67108863 in decimal and hides all drives. For example, if you want to hide drive C, make the third-lowest bit a 1 (this is displayed in binary as 0000000000000000000000100), and then convert the binary string to decimal, which comes out to a decimal value of 4.

1. Open the Common.adm file in a text editor and locate the following section:

   CATEGORY !!Shell
   	CATEGORY !!Restrictions
   		POLICY !!HideDrives
   		VALUENAME "NoDrives"
   		VALUEON NUMERIC 67108863	; low 26 bits on (1 bit per drive)
   		END POLICY
   					

2. Replace the VALUEON NUMERIC value with the new value you created.
3. Save the file and quit.
4. Start Policy Editor, and then click to select the Hide All Drives in My Computer check box. Only the drives specified in the VALUEON NUMERIC value are hidden.

Sample VALUEON NUMERIC values:

• 67108863=hide all drive letters (default)
• 67108859=hide all drive letters but C
• 66060287=hide all drive letters but U
• 66060283=hide all drive letters but C and U
• 66043899=hide all drive letters but C, O, and U
• 00000004=hide only drive C

These values are written to the following registry key:

Using ZAK

Using the ZAK .adm file, you can restrict access to specific drive letters. The following list shows the built-in options:

• Hide all drive letters
• Hide all drive letters but C
• Hide all drive letters but U
• Hide all drive letters but C and U
• Hide all drive letters but C, O, and U

You can expand this list and add your own drive letter restrictions, and then make it available as a menu item in Policy Editor.

To add your own drive restrictions, use the following steps:

1. Open the Zakwinnt.adm file in a text editor and locate the following section:

   CATEGORY !!Shell
   	CATEGORY !!Restrictions
   		POLICY !!HideDrives
   		VALUENAME "NoDrives"
   		ITEMLIST NAME !!HideDrives_all  ; low 26 bits on (1 bit per drive)
   		END POLICY
   					

2. Append to the ITEMLIST NAME value with the new value you created.
3. At the end of the Zakwinnt.adm file (under the [Strings] section), add a line so the new item is displayed as a menu option in Policy Editor. The last line is added to correspond with the new line in the HideDrives section.
   
   Drives="Drives"
   Restrictions="Restrictions"
   HideDrives="Show only selected drives"
   HideDrivesOptions="Choose drives that will be shown"
   HideDrives_all="Do not show any drives"
   HideDrives_C="Only drive C"
   HideDrives_U="Only drive U"
   HideDrives_CU="Drives C and U"
   HideDrives_COU="Drives C, O and U"
   HideDrives_ONLYC="All drives but C"
4. Save the file and quit.
5. Open Policy Editor and click to select the Hide All Drives in My Computer check box. Only the drives specified by the number in ITEMLIST NAME are hidden.

In Policy Editor, locate the ZAK Policies\Windows NT\Drives\Restrictions folder and click Show Only Selected Drives. A new item called "All drives but C," is displayed, which restricts access to drive C but no other drives.