Microsoft KB Archive/220955

= Using System Policies to Hide Specific Drive Letters =

Article ID: 220955

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT Server 4.0 Standard Edition

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This article was previously published under Q220955



SUMMARY
With system policies in Windows NT 4.0, you can use the "Hide All Drives in My Computer" option in Windows NT 4.0 system policies to hide all drives from a specified user. However, you may want to hide some drives but retain access to others. You can do this using a feature of Microsoft Zero Administration Kit (ZAK) for Windows NT (you can also implement this feature using the Common.adm file in a system policy).



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.   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  Replace the VALUEON NUMERIC value with the new value you created. Save the file and quit. 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:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer

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:   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 </li> Append to the ITEMLIST NAME value with the new value you created.</li> 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"</li> Save the file and quit.</li> 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.</li></ol>

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.

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