> ## Documentation Index
> Fetch the complete documentation index at: https://docs.getprimo.com/llms.txt
> Use this file to discover all available pages before exploring further.

# USB storage blocking

> Prevent USB keys, SD cards, and other removable storage from connecting to managed devices.

## Platform compatibility

| macOS | Windows | Linux | iOS / iPadOS | Android |
| ----- | ------- | ----- | ------------ | ------- |
| ✅     | ✅       | ✅     |              |         |

## Set up the control

<Steps>
  <Step title="Set the access mode (Windows only)">
    On Windows, choose the **USB storage access mode** from the dropdown:

    * **Block** — prevents all removable storage devices from connecting.
  </Step>

  <Step title="Select targeting">
    Choose which devices to apply the control to: all devices, specific device groups, or a custom target.
  </Step>
</Steps>

## Modify or remove the control

Disable the control from the profile settings. Disabling stops enforcement but does not remove existing configurations from devices.

## How it works

<Tabs>
  <Tab title="macOS">
    Primo pushes an MDM restriction that blocks removable storage devices from mounting. No additional configuration is required.
  </Tab>

  <Tab title="Windows">
    Primo deploys an MDM policy that blocks the installation and use of removable storage devices based on the configured access mode. Blocked devices appear in Device Manager and users see a notification that the device cannot be used.
  </Tab>

  <Tab title="Linux">
    Primo applies a configuration that blocks UI-based mounting of removable storage devices — for example, prompts from the desktop file manager when a USB drive is connected. The policy is applied system-wide and applies regardless of which user is logged in.

    The control does not block manual mounting from the command line. Users with sufficient privileges can still mount USB storage using `mount`.
  </Tab>
</Tabs>

## Troubleshooting

**A user mounted a USB drive from the terminal after applying the control**

* This is expected behavior on Linux. USB storage blocking only blocks UI-based mounting. Command-line mounting with `mount` is not restricted by this control.