**Important security warning:** USB passthrough comes with many security implications. Please make sure you carefully read and understand the **[security considerations]**. Whenever possible, attach a [block device] instead.
If you've selected to install a usb-qube during system installation, everything is already set up for you in `sys-usb`. If you've later decided to create a usb-qube, please follow [this guide][USB-qube howto].
To use this feature, the[`qubes-usb-proxy`][qubes-usb-proxy] package needs to be installed in the templates used for the USB qube and qubes you want to connect USB devices to.
This section exists for reference or in case something broke and you need to reinstall `qubes-usb-proxy`. Under normal conditions, `qubes-usb-proxy` should already be installed and good to go.
If you receive this error: `ERROR: qubes-usb-proxy not installed in the VM`, you can install the `qubes-usb-proxy` with the package manager in the VM you want to attach the USB device to.
Note: you cannot pass through devices from dom0 (in other words: a [USB qube][USB-qube howto] is required).
`qubes-usb-proxy` should be installed by default in the template VM.
**Warning:** especially keyboards need to be accepted by default when using them to login! Please make sure you carefully read and understood the **[security considerations]** before continuing!
Mouse and keyboard setup are part of [setting up a USB-qube][keyboard setup].
Some USB devices are not compatible with the USB pass-through method Qubes employs.
In situations like these, you can try to pass through the entire USB controller to a qube as PCI device.
However, with this approach one cannot attach single USB devices but has to attach the whole USB controller with whatever USB devices are connected to it.
If you have multiple USB controllers, you must first figure out which PCI device is the right controller.
First, find out which USB bus the device is connected to (note that these steps need to be run from a terminal inside your USB qube):
lsusb
For example, I want to attach a broadband modem to the NetVM.
In the output of `lsusb` it may be listed as something like:
Bus 003 Device 003: ID 413c:818d Dell Computer Corp.
(In this case, the device isn't fully identified)
The device is connected to USB bus \#3.
Check which other devices are connected to the same bus, since *all* of them will be attach to the same VM.
