VirtualBox is an x86 emulator developed by [http://www.virtualbox.org/wiki/innotek innotek] comparable to VMWare. It has a version called VirtualBox Open Source Edition (OSE) which is freely available as Open Source Software under the terms of the GNU General Public License (GPL).

Its a relatively new program and still has some minor issues, but in general it is reliable, stable and, above all, very fast. It has been used successfully to do installation tests with Debian Installer.

This page contains some tips and tricks that can be useful when setting up and using VirtualBox (based on version 1.5.2).

Switching consoles

The normal way to switch consoles in Linux is to use the ctrl-alt-Fx key combination. This does not work for a VirtualBox virtual machine (VM); it will switch consoles for the host system instead.

You should use <Host Key>-Fx instead, where <Host Key> is the key defined in File->Preferences->Input.

This also works for ctrl-alt-del and ctrl-alt-backspace

This is documented in the [http://www.virtualbox.org/download/UserManual.pdf ?VirtalBox user manual] in the section "Keyboard and mouse support in virtual machines", subsection "Typing special characters".

(An alternative method to switch between text consoles is to use alt-left and alt-right, but that does not work for graphical consoles like XOrg or DirectFB.)

Setting up bridged networking for VirtualBox

By default VirtualBox uses NAT for the network interfaces of virtual machines and use an internal DHCP server to obtain an IP address. This works well but the disadvantage is that the machine will not have an IP address visible outside the VM and so you cannot connect to it from the host system or from other systems.

By attaching the VM's interface to "Host Interface" and creating a bridge on the host system, the VM can be made visible on the local network. This also allows to do fun stuff like netbooting the VM (boot from LAN using PXE). It is comparable to the "bridged networking" option in VMWare.

Preparation

First install the package bridge-utils.

Next, change the network configuration of the host system so that the network interface becomes part of a bridge. Note that this requires restarting the network, so be careful when doing this on a remote system!

Change the file /etc/network/interfaces to look something like this:

# The loopback network interface
auto lo
iface lo inet loopback

# An entry for eth0 is no longer needed
#auto eth0
#iface eth0 inet dhcp

# Create the bridge (with the regular IP address of the host)
auto br0
iface br0 inet dhcp
        bridge_ports eth0
        bridge_fd 2.5

In this example the bridge gets its IP address and configuration from DHCP. For static configuration see?BR/usr/share/doc/bridge-utils/README.Debian.gz

Restart the networking of the host system using:

# /etc/init.d/networking restart

After this brctl show should show the bridge and ifconfig should show the bridge has the host's IP address.

Configuring the VirtualBox VM

There are different ways the TAP interface for the VM can be created:

See also the chapter on "Virtual networking" in the [http://www.virtualbox.org/download/UserManual.pdf ?VirtalBox user manual].

Static interfaces

In this case you only need to "define" an interface for use by a particular user once. All defined interfaces are "remembered" in the file /etc/vbox/interfaces and recreated by the VirtualBox init script every time the host system is booted.

Example to create an interface for a user:

# VBoxAddIF vbox0 <username> br0

You can of course create multiple interfaces per users, but all interfaces should have unique names.

To configure the VM to use static bridged networking, go to the "network" page of the VM's settings and change the following fields:

Dynamic interfaces (on demand)

The example below shows the second method. In the example the name of the interface is hardcoded in the script. If you want to be able to create multiple interfaces, you'll have to adapt the script. Note that the script assumes you can execute the needed commands using sudo.

set -e

IF=vbox0
BRIDGE=br0

case "$1" in
    up)
        # Create a TAP network device
        sudo VBoxTunctl -u $LOGNAME -t $IF >/dev/null 2>&1
        # Bring it up (without IP address)
        sudo ifconfig $IF up
        # Add it to the bridge
        sudo brctl addif $BRIDGE $IF

        # Tell VirtualBox the name of the interface
        echo $IF
        ;;
    down)
        sudo VBoxTunctl -d $IF >/dev/null 2>&1
        ;;
esac

Save the script, for example as ~/.VirtualBox/bridge_setup. The script can be tested by running it from the command line. If successful, brctl show should show interface vbox0 added to the bridge.

To configure the VM to use dynamic bridged networking, go to the "network" page of the VM's settings and change the following fields:

When the VM is started after that, the interface should be created automatically and the VM can be used just like it was a system connected directly to your local network.