Protected Devices for NT


This module protects the access to all drives, parallel and serial ports. It sets standard NT ACL on these devices.


This additional program allows to filter the drives displayed in the NT Explorer user interface.



The program must be launched by a user having administrator privileges on the local machine. The System account is a good candidate, but any administrator is suitable.
An easy solution is to run the program during the machine boot in the service AUTOEXNT (from the NT Resource Kit) - but it may be excuted at any time.

The ACL are set immediately but they are volatile. You must re-apply them when the machine was shut down.


This program is an extension to system policies. It is loaded at logon time.

In order to activate it, you must create the value HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\PolicyHandler = "path\hide_dev.dll,ProcessPolicies"


To customise the access, add a value of type REG_SZ or REG_EXPAND_SZ, under the HKEY_LOCAL_MACHINE\SOFTWARE\MarcStern\ProtectedDevices key for each device type or logical drive.
Each value may contain several userid or groupeid separated by a semicolon ';'.
To disable security on one device type (allow access to everybody), use the "default" keyword.

The ACL will be the sum of both the groups/users specified for the drive letter and the one specified in its drive type.

An example of a policy template file (PROT_DEV.ADM) is provided.

Device typeDescription
Drive_FixedHard disks
Drive_RemovableFloppies, ZIP, JAZZ, etc.
Drive_CDCD-ROM, CD-Write, etc.
Drive_RAMRAM drive (in memory)
Drive_RemoteNetwork drives (HIDE_DEV only)
LPT portsParallel ports
COM portsSerial ports
A:logical drive A:
...logical drive ...
Z:logical drive Z:

Special syntax

Some groups are always granted access:

An explicit deny will have no effect on these groups members.


When applying the ACL to a mapped network drive, NT applies it to the mapped directory. Therefor, ACL are not applied on network drives.


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