HowTo: Fix Virtualbox not allowing you to attach USB devices to your virtual machines.

by HyRax January 27, 2010

Virtualbox is a great desktop virtualisation tool, but one of its annoying installation niggles is that when you setup and run a virtual machine you can’t attach any USB devices to it at all because all your USB options in Virtualbox are greyed out.

There are a raft of different solutions to this problem out there ranging from adding an extra line to the /etc/fstab file to modifying your udev rules, but the real cause of this problem is simply that your login name does not have permission to access Virtualbox’s USB driver which interfaces itself between the VM’s virtual USB hardware and your real USB stack.

During the initial installation process, Virtualbox sets up a new group called vboxusers, but it doesn’t put your login name into it. Since using USB in Virtualbox occurs at the device level, your normal user permissions that allow you to run up virtual machines in general are not enough to manipulate Virtualbox’s USB driver. As a result, you cannot tell Virtualbox to attach a given USB device to your virtual machine.

Like most things, this is easily fixed of course.

If your login name is johndoe, all you need to do is jump into a terminal and type in:

$ sudo adduser johndoe vboxusers

…which will add the user johndoe to the vboxusers group.
Now close all applications and windows, and log yourself out of Ubuntu. You don’t need to reboot, but you can if you’re the kind of person who enjoys the subtle pleasures of watching your PC start up.
Log yourself back in again as normal. This will read in your new group membership.
Fire up Virtualbox and start your virtual machine(s) as normal. You will now find that you can attach USB devices to all your VM’s via the Virtualbox Devices menu without any further ado.
Pat yourself on the back – you’re done.

Until Sun Microsystems modify the deb installer to add the current login to the vboxusers group during install, these instructions should apply to just about any version of Virtualbox sporting the problem, on any Linux distro.