> Source: [sk136593](https://support.checkpoint.com/results/sk/sk136593)

# sk136593 - Cannot setup policy to allow one USB device access and block access to another USB device if they have the same hardware parameters

| Property | Value |
|----------|-------|
| Solution ID | sk136593 |
| Date Created | 2018-09-20 |
| Last Modified | 2019-02-12 |
| Technical Level | Advanced |
| Products | Endpoint Security |
| Versions | Cloud, E89.X, E88.X |
| OS | Windows |

## Symptoms

- Two or more USB devices show the same Device Class, Device ID, Serial Number and other parameters. Cannot setup a policy to allow one USB device access and block access to another USB device.

## Cause

Both devices were assigned the same hardware parameters by the manufacturer or device drivers could not provide a unique set of parameters.

MEPP matches (distinguishes) devices by the following parameters:

* Device class - general parameter which tells us what kind of device it is (mouse, storage, optical drive etc).
* Device ID (or Hardware ID in Windows Device Manager) - usually specific to a particular vendor and line of devices.
* Serial number (or [Instance ID](https://docs.microsoft.com/en-us/windows-hardware/drivers/install/instance-ids "Instance ID")) - a device identification string specific to a particular device and persistent across system restart.
* Device Connection, MBR, removal capability. Each of these parameters is binary (can distinguish two devices only).

If two or more devices have identical parameters as described above, MEPP will consider them the same.

## Solution

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