Virtualbox: "USB device in use by someone else" error, how to make (mac) host let go?

Question

I'm trying to set up a USB Fax Modem in Ubuntu through Virtual Box but I'm not sure how to do so.

Host OS = Mac OS X
Virtual Box Guest OS = Ubuntu 12.04
56k USB Fax/Modem = Lenovo 43R1786 (43R1815) by Conexant

On the host os, I can see /dev/tty.usbmodem24680241. I enabled USB Controller, and found my modem as "Conexant USB Modem", so I enabled that. Now, when I run the guest OS, and from the Virtual Box menu for that OS, I go to Devices > USB Devices > Conexant USB Modem, it says:

Failed to attach the USB device Conexant USB modem to the virtual machine Ubuntu32. USB device is in use by someone else. Looks like it means that the host (mac) grabbed the device first. How can I get it to let go so the guest can use it? Am I setting it up the right way?

Thanks!

Solution

I figured it out. You are supposed to:

1. Plug in the device, let the host grab it
2. In the host, go to virtual box, and edit the configuration for the guest to use usb, and add a filter to include the plugged in device
   • Note, you may need to install the Extension pack to enable USB 2.0
3. Unplug the device
4. Start the guest os
5. When the guest os is running, plug in the device.

Virtual box will grab the usb device and make it available for the guest. The guest will then go on and try to identify and configure the device.

Done.

Notes:
Done have a running or saved instance of the guest(virtual machine) running while changing the settings.

Comments

[neufuture]

also make sure you don't have a running or saved instance of the virtual machine while changing the settings.

[tishma]

You only need to complete steps 1-2 once. On subsequent uses, make sure that you follow steps 3-5. (i.e. keep the device unplugged while the guest is booting)

[Andreas]

Thanks a lot, saved me lots of time! :)

[cweitat]

didn't work for me, trying to plug in a wireless usb. this method crashed my mac. any ideas why? running kali on oracle vm. yosemite 10.10