If during installation you enabled the creation of a USB-qube, your system should be setup already and none of the mentioned steps here should be necessary. (Unless you want to [remove your USB-qube](#removing-a-usb-qube).) If for any reason no USB-qube was created during installation, this guide will show you how to do so.
**Caution:** If you want to use a USB-keyboard, please beware of the possibility to lock yourself out! To avoid this problem [enable your keyboard for login](#enable-a-usb-keyboard-for-login)!
A USB qube acts as a secure handler for potentially malicious USB devices, preventing them from coming into contact with dom0 (which could otherwise be fatal to the security of the whole system). It thereby mitigates some of the [security implications](/doc/device-handling-security/#usb-security) of using USB devices.
With a USB qube, every time you connect an untrusted USB drive to a USB port managed by that USB controller, you will have to attach it to the qube in which you wish to use it (if different from the USB qube itself), either by using Qubes VM Manager or the command line (see instructions above).
The USB controller may be assigned on the **Devices** tab of a qube's settings page in Qubes VM Manager or by using the [qvm-pci](/doc/pci-devices/) command.
For guidance on finding the correct USB controller, see the [according passage on PCI-devices](/doc/usb-devices/#finding-the-right-usb-controller).
**Caution:** Please carefully read the [Security Warning about USB Input Devices](/doc/device-handling-security/#security-warning-on-usb-input-devices) before proceeding!
Those steps are not performed by default, because of risk explained in [Security Warning about USB Input Devices](/doc/device-handling-security/#security-warning-on-usb-input-devices).
To allow USB keyboard usage (including early boot for LUKS passphrase), make sure you have the latest `qubes-mgmt-salt-dom0-virtual-machines` package (simply [install dom0 updates](/doc/software-update-dom0/#how-to-update-dom0)) and execute in dom0:
For a confirmation dialog each time the USB keyboard is connected, *which will effectively disable your USB keyboard for login and LUKS decryption*, change this line to:
Additionally, if you want to use USB keyboard to enter LUKS passphrase, it is incompatible with [hiding USB controllers from dom0](#how-to-hide-all-usb-controllers-from-dom0).
You need to revert that procedure (remove `rd.qubes.hide_all_usb` option from files mentioned there) and employ alternative protection during system boot - disconnect other devices during startup.
**Caution:** Please carefully read the [Security Warning about USB Input Devices](/doc/device-handling-security/#security-warning-on-usb-input-devices) before proceeding.
Handling a USB mouse isn't as critical as handling a keyboard, since you can login using the keyboard and accept the popup dialogue using your keyboard alone.
If you want to attach the USB mouse automatically anyway, you have to edit the `qubes.InputMouse` policy file in dom0, located at:
which will ask for conformation each time a USB mouse is attached. If the file is empty or does not exist, maybe something went wrong during setup, try to rerun `qubesctl state.sls qvm.sys-usb` in dom0.
In case you are absolutely sure you do not want to confirm mouse access from `sys-usb` to `dom0`, you may add the following line on top of the file:
**Warning:** A USB keyboard cannot be used to type the disk passphrase if USB controllers were hidden from dom0.
Before hiding USB controllers, make sure your laptop keyboard is not internally connected via USB (by checking output of the `lsusb` command) or that you have a PS/2 keyboard at hand (if using a desktop PC).
Failure to do so will render your system unusable.
If you create a USB qube manually, there will be a brief period of time during the boot process when dom0 will be exposed to your USB controllers (and any attached devices).
This is a potential security risk, since even brief exposure to a malicious USB device could result in dom0 being compromised.
There are two approaches to this problem:
1. Physically disconnect all USB devices whenever you reboot the host.
2. Hide (i.e., blacklist) all USB controllers from dom0.
