Using System Policies to Hide Specific Drive Letters
This article was previously published under Q220955
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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 NTThis 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 ZYXWVUTSRQPONMLKJIHGFEDCBAThis 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.
- 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
Using ZAKUsing 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
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
- Append to the ITEMLIST NAME value with the new value you created.
- 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.
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"
- Save the file and quit.
- 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.
For additional information, please click the article number below to view the article in the Microsoft Knowledge Base:
231289 Using Group Policy Objects to Hide Specified Drives
Article ID: 220955 - Last Review: 12/05/2015 13:11:34 - Revision: 1.1
Microsoft Windows NT Workstation 4.0 Developer Edition, Microsoft Windows NT Server 4.0 Standard Edition
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