Load VirtualBox:

\==============

You need to load the vboxdrv kernel module via /boot/loader.conf:

vboxdrv_load="YES"

You also have to add all users to your vboxusers group in order to use vbox.

% pw groupmod vboxusers -m

Reboot the machine to load the needed kernel modules.

Bridging Support:

\=================

For bridged networking please add the following line to your /etc/rc.conf:

vboxnet_enable="YES"

USB Support:

\============

For USB support your user needs to be in the operator group and needs read

and write permissions to the USB device.

% pw groupmod operator -m

Add the following to /etc/devfs.rules (create if it doesn't exist):

[system=10]

add path 'usb/*' mode 0660 group operator

To load these new rule add the following to /etc/rc.conf:

devfs_system_ruleset="system"

Then restart devfs to load the new rules:

% /etc/rc.d/devfs restart

Troubleshooting:

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Running VirtualBox as non-root user may fail with a fatal error

NS_ERROR_FACTORY_NOT_REGISTERED. In this case delete /tmp/.vbox-*-ipc file.

If you experience "Network: write Failed: Cannot allocate memory" errors

try to increase net.graph.maxdata in /boot/loader.conf

Resource: http://wiki.freebsd.org/VirtualBox