6.3. Security Features

3. Security Features

This section outlines the specific security mechanisms offered by
Oracle VM VirtualBox.

Several aspects of a virtual machine configuration are subject
to security considerations.

Chapter 1. first steps

Welcome to Oracle VM VirtualBox.

Oracle VM VirtualBox is a cross-platform virtualization application. What
does that mean? For one thing, it installs on your existing Intel or
AMD-based computers, whether they are running Windows, Mac OS X,
Linux, or Oracle Solaris operating systems (OSes). Secondly, it
extends the capabilities of your existing computer so that it can
run multiple OSes, inside multiple virtual machines, at the same
time. As an example, you can run Windows and Linux on your Mac, run
Windows Server 2022 on your Linux server, run Linux on your Windows
PC, and so on, all alongside your existing applications. You can
install and run as many virtual machines as you like. The only
practical limits are disk space and memory.

Oracle VM VirtualBox is deceptively simple yet also very powerful. It can
run everywhere from small embedded systems or desktop class machines
all the way up to datacenter deployments and even Cloud

The following screenshot shows how Oracle VM VirtualBox, installed on an
Apple Mac OS X computer, is running Windows Server 2022 in a virtual
machine window.

In this User Manual, we will begin simply with a quick introduction
to virtualization and how to get your first virtual machine running
with the easy-to-use Oracle VM VirtualBox graphical user interface.
Subsequent chapters will go into much more detail covering more
powerful tools and features, but fortunately, it is not necessary to
read the entire User Manual before you can use Oracle VM VirtualBox.

You can find a summary of Oracle VM VirtualBox’s capabilities in
Section 1.3, “Features Overview”. For existing Oracle VM VirtualBox
users who just want to find out what is new in this release, see the
Chapter 15, Change Log.

The techniques and features that Oracle VM VirtualBox provides are
useful in the following scenarios:

  • Running multiple operating systems
    Oracle VM VirtualBox enables you to run
    more than one OS at a time. This way, you can run software
    written for one OS on another, such as Windows software on
    Linux or a Mac, without having to reboot to use it. Since you
    can configure what kinds of virtual
    hardware should be presented to each such OS, you can install
    an old OS such as DOS or OS/2 even if your real computer’s
    hardware is no longer supported by that OS.

  • Easier software
    Software vendors can use virtual
    machines to ship entire software configurations. For example,
    installing a complete mail server solution on a real machine
    can be a tedious task. With Oracle VM VirtualBox, such a complex
    setup, often called an appliance, can be
    packed into a virtual machine. Installing and running a mail
    server becomes as easy as importing such an appliance into
    Oracle VM VirtualBox.

  • Testing and disaster
    Once installed, a virtual machine and its
    virtual hard disks can be considered a
    container that can be arbitrarily frozen,
    woken up, copied, backed up, and transported between hosts.

    On top of that, with the use of another Oracle VM VirtualBox feature
    called snapshots, one can save a
    particular state of a virtual machine and revert back to that
    state, if necessary. This way, one can freely experiment with
    a computing environment. If something goes wrong, such as
    problems after installing software or infecting the guest with
    a virus, you can easily switch back to a previous snapshot and
    avoid the need of frequent backups and restores.

    Any number of snapshots can be created, allowing you to travel
    back and forward in virtual machine time. You can delete
    snapshots while a VM is running to reclaim disk space.

  • Infrastructure consolidation.
    Virtualization can significantly reduce hardware and
    electricity costs. Most of the time, computers today only use
    a fraction of their potential power and run with low average
    system loads. A lot of hardware resources as well as
    electricity is thereby wasted. So, instead of running many
    such physical computers that are only partially used, one can
    pack many virtual machines onto a few powerful hosts and
    balance the loads between them.

When dealing with virtualization, and also for understanding the
following chapters of this documentation, it helps to acquaint
oneself with a bit of crucial terminology, especially the
following terms:

  • Host operating system (host
    This is the OS of the physical computer on
    which Oracle VM VirtualBox was installed. There are versions of
    Oracle VM VirtualBox for Windows, Mac OS X, Linux, and Oracle
    Solaris hosts. See Section 1.4, “Supported Host Operating Systems”.

    Most of the time, this manual discusses all Oracle VM VirtualBox
    versions together. There may be platform-specific differences
    which we will point out where appropriate.

  • Guest operating system (guest
    This is the OS that is running inside the
    virtual machine. Theoretically, Oracle VM VirtualBox can run any x86
    OS such as DOS, Windows, OS/2, FreeBSD, and OpenBSD. But to
    achieve near-native performance of the guest code on your
    machine, we had to go through a lot of optimizations that are
    specific to certain OSes. So while your favorite OS
    may run as a guest, we officially support
    and optimize for a select few, which include the most common

    See Section 3.1, “Supported Guest Operating Systems”.

  • Virtual machine (VM). This is
    the special environment that Oracle VM VirtualBox creates for your
    guest OS while it is running. In other words, you run your
    guest OS in a VM. Normally, a VM is shown
    as a window on your computer’s desktop. Depending on which of
    the various frontends of Oracle VM VirtualBox you use, the VM might
    be shown in full screen mode or remotely on another computer.

    Internally, Oracle VM VirtualBox treats a VM as a set of parameters
    that specify its behavior. Some parameters describe hardware
    settings, such as the amount of memory and number of CPUs
    assigned. Other parameters describe the state information,
    such as whether the VM is running or saved.

    You can view these VM settings in the VirtualBox Manager
    window, the Settings dialog,
    and by running the VBoxManage command. See
    Chapter 8, VBoxManage.

  • Guest Additions. This refers
    to special software packages which are shipped with
    Oracle VM VirtualBox but designed to be installed
    inside a VM to improve performance of the
    guest OS and to add extra features. See
    Chapter 4, Guest Additions.

The following is a brief outline of Oracle VM VirtualBox’s main

  • Portability. Oracle VM VirtualBox
    runs on a large number of 64-bit host operating systems. See
    Section 1.4, “Supported Host Operating Systems”.

    Oracle VM VirtualBox is a so-called hosted
    hypervisor, sometimes referred to as a type
    hypervisor. Whereas a
    bare-metal or type 1
    hypervisor would run directly on the hardware, Oracle VM VirtualBox
    requires an existing OS to be installed. It can thus run
    alongside existing applications on that host.

    To a very large degree, Oracle VM VirtualBox is functionally
    identical on all of the host platforms, and the same file and
    image formats are used. This enables you to run virtual
    machines created on one host on another host with a different
    host OS. For example, you can create a virtual machine on
    Windows and then run it under Linux.

    In addition, virtual machines can easily be imported and
    exported using the Open Virtualization Format (OVF), an
    industry standard created for this purpose. You can even
    import OVFs that were created with a different virtualization
    software. See Section 1.14, “Importing and Exporting Virtual Machines”.

    For users of Oracle Cloud Infrastructure the functionality extends to exporting and
    importing virtual machines to and from the cloud. This
    simplifies development of applications and deployment to the
    production environment. See
    Section 1.15.7, “Exporting an Appliance to Oracle Cloud Infrastructure”.

  • Guest Additions: shared folders,
    seamless windows, 3D virtualization.
    Oracle VM VirtualBox Guest Additions are software packages which can
    be installed inside of supported guest
    systems to improve their performance and to provide additional
    integration and communication with the host system. After
    installing the Guest Additions, a virtual machine will support
    automatic adjustment of video resolutions, seamless windows,
    accelerated 3D graphics and more. See
    Chapter 4, Guest Additions.

    In particular, Guest Additions provide for shared
    , which let you access files on the host
    system from within a guest machine. See
    Section 4.3, “Shared Folders”.

  • Great hardware support. Among
    other features, Oracle VM VirtualBox supports the following:

    • Guest multiprocessing
      Oracle VM VirtualBox can present up to 32
      virtual CPUs to each virtual machine, irrespective of how
      many CPU cores are physically present on your host.

    • USB device support.
      Oracle VM VirtualBox implements a virtual USB controller and
      enables you to connect arbitrary USB devices to your
      virtual machines without having to install device-specific
      drivers on the host. USB support is not limited to certain
      device categories. See Section 3.11.1, “USB Settings”.

    • Hardware compatibility.
      Oracle VM VirtualBox virtualizes a vast array of virtual
      devices, among them many devices that are typically
      provided by other virtualization platforms. That includes
      IDE, SCSI, and SATA hard disk controllers, several virtual
      network cards and sound cards, virtual serial and parallel
      ports and an Input/Output Advanced Programmable Interrupt
      Controller (I/O APIC), which is found in many computer
      systems. This enables easy cloning of disk images from
      real machines and importing of third-party virtual
      machines into Oracle VM VirtualBox.

    • Full ACPI support. The
      Advanced Configuration and Power Interface (ACPI) is fully
      supported by Oracle VM VirtualBox. This enables easy cloning of
      disk images from real machines or third-party virtual
      machines into Oracle VM VirtualBox. With its unique
      ACPI power status support,
      Oracle VM VirtualBox can even report to ACPI-aware guest OSes
      the power status of the host. For mobile systems running
      on battery, the guest can thus enable energy saving and
      notify the user of the remaining power, for example in
      full screen modes.

    • Multiscreen resolutions.
      Oracle VM VirtualBox virtual machines support screen resolutions
      many times that of a physical screen, allowing them to be
      spread over a large number of screens attached to the host

    • Built-in iSCSI support.
      This unique feature enables you to connect a virtual
      machine directly to an iSCSI storage server without going
      through the host system. The VM accesses the iSCSI target
      directly without the extra overhead that is required for
      virtualizing hard disks in container files. See
      Section 5.10, “iSCSI Servers”.

    • PXE Network boot. The
      integrated virtual network cards of Oracle VM VirtualBox fully
      support remote booting using the Preboot Execution
      Environment (PXE).

  • Multigeneration branched
    Oracle VM VirtualBox can save arbitrary
    snapshots of the state of the virtual machine. You can go back
    in time and revert the virtual machine to any such snapshot
    and start an alternative VM configuration from there,
    effectively creating a whole snapshot tree. See
    Section 1.10, “Snapshots”. You can create and delete
    snapshots while the virtual machine is running.

  • VM groups. Oracle VM VirtualBox
    provides a groups feature that enables the user to organize
    and control virtual machines collectively, as well as
    individually. In addition to basic groups, it is also possible
    for any VM to be in more than one group, and for groups to be
    nested in a hierarchy. This means you can have groups of
    groups. In general, the operations that can be performed on
    groups are the same as those that can be applied to individual
    VMs: Start, Pause, Reset, Close (Save state, Send Shutdown,
    Poweroff), Discard Saved State, Show in File System, Sort.

  • Clean architecture and unprecedented
    Oracle VM VirtualBox has an extremely modular
    design with well-defined internal programming interfaces and a
    clean separation of client and server code. This makes it easy
    to control it from several interfaces at once. For example,
    you can start a VM simply by clicking on a button in the
    Oracle VM VirtualBox graphical user interface and then control that
    machine from the command line, or even remotely. See
    Section 1.17, “Alternative Front-Ends”.

    Due to its modular architecture, Oracle VM VirtualBox can also
    expose its full functionality and configurability through a
    comprehensive software development kit
    which enables integration of Oracle VM VirtualBox
    with other software systems. See
    Chapter 11, Oracle VM VirtualBox Programming Interfaces.

  • Remote machine display. The
    VirtualBox Remote Desktop Extension (VRDE) enables
    high-performance remote access to any running virtual machine.
    This extension supports the Remote Desktop Protocol (RDP)
    originally built into Microsoft Windows, with special
    additions for full client USB support.

    The VRDE does not rely on the RDP server that is built into
    Microsoft Windows. Instead, the VRDE is plugged directly into
    the virtualization layer. As a result, it works with guest
    OSes other than Windows, even in text mode, and does not
    require application support in the virtual machine either. The
    VRDE is described in detail in Section 7.1, “Remote Display (VRDP Support)”.

    On top of this special capacity, Oracle VM VirtualBox offers you
    more unique features:

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Currently, Oracle VM VirtualBox runs on the following host OSes:

  • Windows hosts (64-bit):

    • Windows 8.1

    • Windows 10 RTM (1507 / 2022 LTSB) build 10240

    • Windows 10 Anniversary Update (1607 / 2022 LTSB) build

    • Windows 10 Fall Creators Update (1709) build 16299

    • Windows 10 April 2022 Update (1803) build 17134

    • Windows 10 October 2022 Update (1809 / 2022 LTSC) build

    • Windows 10 May 2022 Update (19H1 / 1903) build 18362

    • Windows 10 November 2022 Update (19H2 / 1909) build 18363

    • Windows Server 2022

    • Windows Server 2022 R2

    • Windows Server 2022

    • Windows Server 2022

  • Mac OS X hosts (64-bit):

    • 10.13 (High Sierra)

    • 10.14 (Mojave)

    • 10.15 (Catalina)

    Intel hardware is required. See also
    Chapter 14, Known Limitations.

  • Linux hosts (64-bit).
    Includes the following:

    • Ubuntu 18.04 LTS, 19.03 and 19.10

    • Debian GNU/Linux 9 (“Stretch”) and 10 (“Buster”)

    • Oracle Linux 6, 7 and 8

    • CentOS/Red Hat Enterprise Linux 6, 7 and 8

    • Fedora 30 and 31

    • Gentoo Linux

    • SUSE Linux Enterprise server 12 and 15

    • openSUSE Leap 15.1

    It should be possible to use Oracle VM VirtualBox on most systems
    based on Linux kernel 2.6, 3.x, 4.x or 5.x using either the
    Oracle VM VirtualBox installer or by doing a manual installation.
    See Section 2.3, “Installing on Linux Hosts”. However, the
    formally tested and supported Linux distributions are those
    for which we offer a dedicated package.

    Note that Linux 2.4-based host OSes are no longer supported.

  • Oracle Solaris hosts (64-bit
    The following versions are supported with
    the restrictions listed in Chapter 14, Known Limitations:

Note that any feature which is marked as
experimental is not supported. Feedback and
suggestions about such features are welcome.

Oracle VM VirtualBox comes in many different packages, and installation
depends on your host OS. If you have installed software before,
installation should be straightforward. On each host platform,
Oracle VM VirtualBox uses the installation method that is most common
and easy to use. If you run into trouble or have special
requirements, see Chapter 2, Installation Details for details
about the various installation methods.

Oracle VM VirtualBox is split into the following components:

  • Base package. The base
    package consists of all open source components and is licensed
    under the GNU General Public License V2.

  • Extension packs. Additional
    extension packs can be downloaded which extend the
    functionality of the Oracle VM VirtualBox base package. Currently,
    Oracle provides a single extension pack, available from:
    http://www.vhod-v-lichnyj-kabinet.ru. The extension pack
    provides the following added functionality:

    Oracle VM VirtualBox extension packages have a
    .vbox-extpack file name extension. To
    install an extension, simply double-click on the package file
    and a Network Operations
    window is shown to guide you through the
    required steps.

    To view the extension packs that are currently installed,
    start the VirtualBox Manager, as shown in
    Section 1.6, “Starting Oracle VM VirtualBox”. From the
    File menu, select
    Preferences. In the window
    that displays, go to the
    Extensions category. This
    shows you the extensions which are currently installed, and
    enables you to remove a package or add a new package.

    Alternatively, you can use the VBoxManage
    command line. See Section 8.41, “VBoxManage extpack”.

Click New in the VirtualBox
Manager window. A wizard is shown, to guide you through setting up
a new virtual machine (VM).

On the following pages, the wizard will ask you for the bare
minimum of information that is needed to create a VM, in

  1. The Name of the VM you choose
    is shown in the machine list of the VirtualBox Manager window
    and is also used for the VM’s files on disk.

    Be sure to assign each VM an informative name that describes
    the OS and software running on the VM. For example,
    Windows 10 with Visio.

  2. The Machine Folder is the
    location where VMs are stored on your computer. The default
    folder location is shown.

  3. For Operating System Type,
    select the OS that you want to install. The supported OSes are
    grouped. If you want to install something very unusual that is
    not listed, select Other.
    Depending on your selection, Oracle VM VirtualBox will enable or
    disable certain VM settings that your guest OS may require.
    This is particularly important for 64-bit guests. See
    Section 3.1.2, “64-bit Guests”. It is therefore
    recommended to always set it to the correct value.

  4. On the next page, select the Memory
    that Oracle VM VirtualBox should allocate every
    time the virtual machine is started. The amount of memory
    given here will be taken away from your host machine and
    presented to the guest OS, which will report this size as the
    virtual computer’s installed RAM.

    Always ensure that the host OS has enough RAM remaining. If
    insufficient RAM remains, the system might excessively swap
    memory to the hard disk, which effectively brings the host
    system to a standstill.

    As with the other settings, you can change this setting later,
    after you have created the VM.

  5. Next, you must specify a Virtual Hard
    for your VM.

    There are many and potentially complicated ways in which
    Oracle VM VirtualBox can provide hard disk space to a VM, see
    Chapter 5, Virtual Storage, but the most common way is to use
    a large image file on your physical hard disk, whose contents
    Oracle VM VirtualBox presents to your VM as if it were a complete
    hard disk. This file then represents an entire hard disk, so
    you can even copy it to another host and use it with another
    Oracle VM VirtualBox installation.

    The wizard displays the following window:

    At this screen, you have the following options:

    If you are using Oracle VM VirtualBox for the first time, you will
    want to create a new disk image. Click the
    Create button.

    This displays another window, the Create
    Virtual Hard Disk Wizard
    wizard. This wizard helps
    you to create a new disk image file in the new virtual
    machine’s folder.

    Oracle VM VirtualBox supports the following types of image files:

    For details about the differences, see
    Section 5.2, “Disk Image Files (VDI, VMDK, VHD, HDD)”.

    To prevent your physical hard disk (host OS) from filling up,
    Oracle VM VirtualBox limits the size of the image file. But the
    image file must be large enough to hold the contents of the
    guest OS and the applications you want to install. For a
    Windows or Linux guest, you will probably need several
    gigabytes for any serious use. The limit of the image file
    size can be changed later, see
    Section 8.22, “VBoxManage modifymedium”.

    After having selected or created your image file, click
    Next to go to the next page.

  6. Click Create, to create your
    new virtual machine. The virtual machine is displayed in the
    list on the left side of the VirtualBox Manager window, with
    the name that you entered initially.

To start a virtual machine, you have several options:

Starting a virtual machine displays a new window, and the virtual
machine which you selected will boot up. Everything which would
normally be seen on the virtual system’s monitor is shown in the
window. See the screenshot image in
Chapter 1, First Steps.

In general, you can use the virtual machine as you would use a
real computer. There are couple of points worth mentioning

When a VM is started for the first time, the
First Start Wizard, is
displayed. This wizard helps you to select an installation
medium. Since the VM is created empty, it would otherwise behave
just like a real computer with no OS installed. It will do
nothing and display an error message that no bootable OS was

For this reason, the wizard helps you to select a medium to
install an OS from.

  • If you have physical CD or DVD media from which you want to
    install your guest OS, such as a Windows installation CD or
    DVD, put the media into your host’s CD or DVD drive.

    In the wizard’s drop-down list of installation media, select
    Host Drive with the correct
    drive letter. In the case of a Linux host, choose a device
    file. This will allow your VM to access the media in your
    host drive, and you can proceed to install from there.

  • If you have downloaded installation media from the Internet
    in the form of an ISO image file such as with a Linux
    distribution, you would normally burn this file to an empty
    CD or DVD and proceed as described above. With
    Oracle VM VirtualBox however, you can skip this step and mount the
    ISO file directly. Oracle VM VirtualBox will then present this
    file as a CD or DVD-ROM drive to the virtual machine, much
    like it does with virtual hard disk images.

    In this case, the wizard’s drop-down list contains a list of
    installation media that were previously used with
    Oracle VM VirtualBox.

    If your medium is not in the list, especially if you are
    using Oracle VM VirtualBox for the first time, click the small
    folder icon next to the drop-down list to display a standard
    file dialog. Here you can pick an image file on your host

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After completing the choices in the wizard, you will be able to
install your OS.

Oracle VM VirtualBox provides a virtual USB tablet device to new
virtual machines through which mouse events are communicated to
the guest OS. If you are running a modern guest OS that can
handle such devices, mouse support may work out of the box
without the mouse being captured as
described below. See Section 3.5.1, “Motherboard Tab”.

Otherwise, if the virtual machine detects only standard PS/2
mouse and keyboard devices, since the OS in the virtual machine
does not know that it is not running on a real computer, it
expects to have exclusive control over your keyboard and mouse.
But unless you are running the VM in full screen mode, your VM
needs to share keyboard and mouse with other applications and
possibly other VMs on your host.

After installing a guest OS and before you install the Guest
Additions, described later, either your VM or the rest of your
computer can “own” the keyboard and the mouse. Both cannot own
the keyboard and mouse at the same time. You will see a
second mouse pointer which is always
confined to the limits of the VM window. You activate the VM by
clicking inside it.

To return ownership of keyboard and mouse to your host OS,
Oracle VM VirtualBox reserves a special key on your keyboard: the
Host key. By default, this is the
right Ctrl key on your keyboard. On a Mac
host, the default Host key is the left Command key. You can
change this default in the Oracle VM VirtualBox Global Settings. See
Section 1.16, “Global Settings”. The current setting for the
Host key is always displayed at the bottom right of your VM

This means the following:

  • Your keyboard is owned by
    the VM if the VM window on your host desktop has the
    keyboard focus. If you have many windows open in your guest
    OS, the window that has the focus in your VM is used. This
    means that if you want to enter text within your VM, click
    on the title bar of your VM window first.

    To release keyboard ownership, press the Host key. As
    explained above, this is typically the right Ctrl key.

    Note that while the VM owns the keyboard, some key
    sequences, such as Alt Tab, will no longer be seen by the
    host, but will go to the guest instead. After you press the
    Host key to reenable the host keyboard, all key presses will
    go through the host again, so that sequences such as Alt Tab
    will no longer reach the guest. For technical reasons it may
    not be possible for the VM to get all keyboard input even
    when it does own the keyboard. Examples of this are the
    Ctrl Alt Del sequence on Windows hosts or single keys
    grabbed by other applications on X11 hosts such as the GNOME
    desktop Locate Pointer feature.

  • Your mouse is owned by the
    VM only after you have clicked in the VM window. The host
    mouse pointer will disappear, and your mouse will drive the
    guest’s pointer instead of your normal mouse pointer.

    Note that mouse ownership is independent of that of the
    keyboard. Even after you have clicked on a titlebar to be
    able to enter text into the VM window, your mouse is not
    necessarily owned by the VM yet.

    To release ownership of your mouse by the VM, press the Host

As this behavior is inconvenient, Oracle VM VirtualBox provides a set
of tools and device drivers for guest systems called the
Oracle VM VirtualBox Guest Additions. These tools make VM keyboard and
mouse operations much more seamless. Most importantly, the Guest
Additions suppress the second “guest” mouse pointer and make
your host mouse pointer work directly in the guest. See
Chapter 4, Guest Additions.

Some OSes expect certain key combinations to initiate certain
procedures. The key combinations that you type into a VM might
target the host OS, the Oracle VM VirtualBox software, or the guest
OS. The recipient of these keypresses depends on a number of
factors, including the key combination itself.

  • Host OSes reserve certain key combinations for themselves.
    For example, you cannot use the
    Ctrl Alt Delete combination
    to reboot the guest OS in your VM because this key
    combination is usually hard-wired into the host OS. So, even
    though both the Windows and Linux OSes intercept this key
    combination, only the host OS would be rebooted.

    On Linux and Oracle Solaris hosts, which use the X Window
    System, the key combination
    Ctrl Alt Backspace normally
    resets the X server and restarts the entire graphical user
    interface. As the X server intercepts this combination,
    pressing it will usually restart your
    host graphical user interface and kill
    all running programs, including Oracle VM VirtualBox, in the

    On Linux hosts supporting virtual terminals, the key
    combination Ctrl Alt Fx,
    where Fx is one of the function keys from F1 to F12,
    normally enables you to switch between virtual terminals. As
    with Ctrl Alt Delete, these
    combinations are intercepted by the host OS and therefore
    always switch terminals on the host.

    If, instead, you want to send these key combinations to the
    guest OS in the virtual machine, you
    will need to use one of the following methods:

  • For some other keyboard combinations such as
    Alt Tab to switch between
    open windows, Oracle VM VirtualBox enables you to configure
    whether these combinations will affect the host or the
    guest, if a virtual machine currently has the focus. This is
    a global setting for all virtual machines and can be found
    under File,

  • A soft keyboard can be used to input key combinations in the
    guest. See Section 1.18, “Soft Keyboard”.

You can resize the VM’s window while that VM is running. When
you do, the window is scaled as follows:

  1. If you have scaled mode
    enabled, then the virtual machine’s screen will be scaled to
    the size of the window. This can be useful if you have many
    machines running and want to have a look at one of them
    while it is running in the background. Alternatively, it
    might be useful to enlarge a window if the VM’s output
    screen is very small, for example because you are running an
    old OS in it.

    To enable scaled mode, press Host key
    , or select Scaled
    from the
    View menu in the VM window.
    To leave scaled mode, press Host key

    The aspect ratio of the guest screen is preserved when
    resizing the window. To ignore the aspect ratio, press
    Shift during the resize

    See Chapter 14, Known Limitations for additional remarks.

  2. If you have the Guest Additions installed and they support
    automatic resizing, the
    Guest Additions will automatically adjust the screen
    resolution of the guest OS. For example, if you are running
    a Windows guest with a resolution of 1024×768 pixels and you
    then resize the VM window to make it 100 pixels wider, the
    Guest Additions will change the Windows display resolution
    to 1124×768.

    See Chapter 4, Guest Additions.

  3. Otherwise, if the window is bigger than the VM’s screen, the
    screen will be centered. If it is smaller, then scroll bars
    will be added to the machine window.

When you click on the Close
button of your virtual machine window, at the top right of the
window, just like you would close any other window on your
system, Oracle VM VirtualBox asks you whether you want to save or
power off the VM. As a shortcut, you can also press
Host key Q.

The difference between the three options is crucial. They mean
the following:

  • Save the machine state:
    With this option, Oracle VM VirtualBox
    freezes the virtual machine by
    completely saving its state to your local disk.

    When you start the VM again later, you will find that the VM
    continues exactly where it was left off. All your programs
    will still be open, and your computer resumes operation.
    Saving the state of a virtual machine is thus in some ways
    similar to suspending a laptop computer by closing its lid.

  • Send the shutdown signal.
    This will send an ACPI shutdown signal to the virtual
    machine, which has the same effect as if you had pressed the
    power button on a real computer. This should trigger a
    proper shutdown mechanism from within the VM.

  • Power off the machine: With
    this option, Oracle VM VirtualBox also stops running the virtual
    machine, but without saving its state.

    As an exception, if your virtual machine has any snapshots,
    see Section 1.10, “Snapshots”, you can use this option to
    quickly restore the current
    of the virtual machine. In that case,
    powering off the machine will not disrupt its state, but any
    changes made since that snapshot was taken will be lost.

The Discard button in the
VirtualBox Manager window discards a virtual machine’s saved
state. This has the same effect as powering it off, and the same
warnings apply.

VM groups enable the user to create ad hoc groups of VMs, and to
manage and perform functions on them collectively, as well as

The following figure shows VM groups displayed in VirtualBox

The following features are available for groups:

  • Create a group using the VirtualBox Manager. Do one of the

  • Create and manage a group using the command line. Do one of
    the following:

  • Create multiple groups. For example:

    VBoxManage modifyvm "vm01" --groups "/TestGroup,/TestGroup2"

    This command creates the groups “TestGroup” and “TestGroup2”,
    if they do not exist, and attaches the VM “vm01” to both of

  • Create nested groups, having a group hierarchy. For example:

    VBoxManage modifyvm "vm01" --groups "/TestGroup/TestGroup2"

    This command attaches the VM “vm01” to the subgroup
    “TestGroup2” of the “TestGroup” group.

  • The following is a summary of group commands: Start, Pause,
    Reset, Close (save state, send shutdown signal, poweroff),
    Discard Saved State, Show in File System, Sort.

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With snapshots, you can save a particular state of a virtual
machine for later use. At any later time, you can revert to that
state, even though you may have changed the VM considerably since
then. A snapshot of a virtual machine is thus similar to a machine
in Saved state, but there can be many of them, and these saved
states are preserved.

To see the snapshots of a virtual machine, click on the machine
name in VirtualBox Manager. Then click the
List icon next to the machine
name, and select Snapshots. Until
you take a snapshot of the machine, the list of snapshots will be
empty except for the Current
item, which represents the “now” point in the
lifetime of the virtual machine.

There are three operations related to snapshots, as follows:

  1. Take a snapshot. This makes
    a copy of the machine’s current state, to which you can go
    back at any given time later.

    In either case, a window is displayed prompting you for a
    snapshot name. This name is purely for reference purposes to
    help you remember the state of the snapshot. For example, a
    useful name would be “Fresh installation from scratch, no
    Guest Additions”, or “Service Pack 3 just installed”. You
    can also add a longer text in the
    Description field.

    Your new snapshot will then appear in the snapshots list.
    Underneath your new snapshot, you will see an item called
    Current State, signifying
    that the current state of your VM is a variation based on
    the snapshot you took earlier. If you later take another
    snapshot, you will see that they are displayed in sequence,
    and that each subsequent snapshot is derived from an earlier

    Oracle VM VirtualBox imposes no limits on the number of snapshots
    you can take. The only practical limitation is disk space on
    your host. Each snapshot stores the state of the virtual
    machine and thus occupies some disk space. See
    Section 1.10.2, “Snapshot Contents” for details on what is
    stored in a snapshot.

  2. Restore a snapshot. In the
    list of snapshots, right-click on any snapshot you have
    taken and select Restore.
    By restoring a snapshot, you go back or forward in time. The
    current state of the machine is lost, and the machine is
    restored to the exact state it was in when the snapshot was

    To avoid losing the current state when restoring a snapshot,
    you can create a new snapshot before the restore operation.

    By restoring an earlier snapshot and taking more snapshots
    from there, it is even possible to create a kind of
    alternate reality and to switch between these different
    histories of the virtual machine. This can result in a whole
    tree of virtual machine snapshots, as shown in the
    screenshot above.

  3. Delete a snapshot. This
    does not affect the state of the virtual machine, but only
    releases the files on disk that Oracle VM VirtualBox used to store
    the snapshot data, thus freeing disk space. To delete a
    snapshot, right-click on the snapshot name in the snapshots
    tree and select Delete.
    Snapshots can be deleted even while a machine is running.

    There are some situations which cannot be handled while a VM
    is running, and you will get an appropriate message that you
    need to perform this snapshot deletion when the VM is shut

Think of a snapshot as a point in time that you have preserved.
More formally, a snapshot consists of the following:

  • The snapshot contains a complete copy of the VM settings,
    including the hardware configuration, so that when you
    restore a snapshot, the VM settings are restored as well.
    For example, if you changed the hard disk configuration or
    the VM’s system settings, that change is undone when you
    restore the snapshot.

    The copy of the settings is stored in the machine
    configuration, an XML text file, and thus occupies very
    little space.

  • The complete state of all the virtual disks attached to the
    machine is preserved. Going back to a snapshot means that
    all changes that had been made to the machine’s disks, file
    by file and bit by bit, will be undone as well. Files that
    were since created will disappear, files that were deleted
    will be restored, changes to files will be reverted.

    Strictly speaking, this is only true for virtual hard disks
    in “normal” mode. You can configure disks to behave
    differently with snapshots, see
    Section 5.4, “Special Image Write Modes”. In technical terms, it is
    not the virtual disk itself that is restored when a snapshot
    is restored. Instead, when a snapshot is taken,
    Oracle VM VirtualBox creates differencing images which contain
    only the changes since the snapshot were taken. When the
    snapshot is restored, Oracle VM VirtualBox throws away that
    differencing image, thus going back to the previous state.
    This is both faster and uses less disk space. For the
    details, which can be complex, see
    Section 5.5, “Differencing Images”.

    Creating the differencing image as such does not occupy much
    space on the host disk initially, since the differencing
    image will initially be empty and grow dynamically later
    with each write operation to the disk. The longer you use
    the machine after having created the snapshot, however, the
    more the differencing image will grow in size.

  • If you took a snapshot while the machine was running, the
    memory state of the machine is also saved in the snapshot.
    This is in the same way that memory can be saved when you
    close a VM window. When you restore such a snapshot,
    execution resumes at exactly the point when the snapshot was

    The memory state file can be as large as the memory size of
    the VM and will therefore occupy considerable disk space.

Oracle VM VirtualBox can import and export virtual machines in the
following formats:

OVF is a cross-platform standard supported by many
virtualization products which enables the creation of ready-made
virtual machines that can then be imported into a hypervisor
such as Oracle VM VirtualBox. Oracle VM VirtualBox makes OVF import and
export easy to do, using the VirtualBox Manager window or the
command-line interface.

Using OVF enables packaging of virtual
. These are disk images, together with
configuration settings that can be distributed easily. This way
one can offer complete ready-to-use software packages, including
OSes with applications, that need no configuration or
installation except for importing into Oracle VM VirtualBox.

Appliances in OVF format can appear in the following variants:

This section describes how to use the features of Oracle VM VirtualBox
to integrate with Oracle Cloud Infrastructure.

Integrating with Oracle Cloud Infrastructure involves the following steps:

Oracle VM VirtualBox uses a cloud profile to
connect to Oracle Cloud Infrastructure. A cloud profile is a text file that contains
details of your key files and Oracle Cloud Identifier (OCID)
resource identifiers for your cloud account, such as the

You can create a cloud profile in the following ways:

  • Automatically, by using the Cloud
    Profile Manager
    . See
    Section 1.15.5, “Using the Cloud Profile Manager”.

    The Cloud Profile Manager is a component of Oracle VM VirtualBox
    that enables you to create, edit, and manage cloud profiles
    for your cloud service accounts.

  • Automatically, by using the VBoxManage
    command. See
    Section 8.44, “VBoxManage cloudprofile”.

  • Manually, by creating an oci_config
    file in your Oracle VM VirtualBox global configuration directory.
    For example, this is
    $HOME/.config/VirtualBox/oci_config on
    a Linux host.

  • Manually, by creating a config file in
    your Oracle Cloud Infrastructure configuration directory. For example, this is
    $HOME/.oci/config on a Linux host.

    This is the same file that is used by the Oracle Cloud Infrastructure command line

    Oracle VM VirtualBox automatically uses the
    config file if no cloud profile file is
    present in your global configuration directory.
    Alternatively, you can import this file manually into the
    Cloud Profile Manager.

Oracle VM VirtualBox supports the export of VMs to an Oracle Cloud Infrastructure service.
The exported VM is stored on Oracle Cloud Infrastructure as a custom Linux image. You
can configure whether a cloud instance is created and started
after the export process has completed.

Use the following steps to export a VM to Oracle Cloud Infrastructure:

You can also use the VBoxManage export
command to export a VM to Oracle Cloud Infrastructure. See
Section 8.11.2, “Export to Oracle Cloud Infrastructure”.

As briefly mentioned in Section 1.3, “Features Overview”,
Oracle VM VirtualBox has a very flexible internal design that enables
you to use multiple interfaces to control the same virtual
machines. For example, you can start a virtual machine with the
VirtualBox Manager window and then stop it from the command line.
With Oracle VM VirtualBox’s support for the Remote Desktop Protocol
(RDP), you can even run virtual machines remotely on a headless
server and have all the graphical output redirected over the

The following front-ends are shipped in the standard
Oracle VM VirtualBox package:

  • VirtualBox. This is the
    VirtualBox Manager, a graphical user interface that uses the
    Qt toolkit. This interface is described throughout this
    manual. While this is the simplest and easiest front-end to
    use, some of the more advanced Oracle VM VirtualBox features are not

  • VBoxManage. A command-line
    interface for automated and detailed control of every aspect
    of Oracle VM VirtualBox. See
    Chapter 8, VBoxManage.

  • VBoxHeadless. A front-end
    that produces no visible output on the host at all, but can
    act as a RDP server if the VirtualBox Remote Desktop Extension
    (VRDE) is installed and enabled for the VM. As opposed to the
    other graphical interfaces, the headless front-end requires no
    graphics support. This is useful, for example, if you want to
    host your virtual machines on a headless Linux server that has
    no X Window system installed. See
    Section 7.1.2, “VBoxHeadless, the Remote Desktop Server”.

If the above front-ends still do not satisfy your particular
needs, it is possible to create yet another front-end to the
complex virtualization engine that is the core of Oracle VM VirtualBox,
as the Oracle VM VirtualBox core neatly exposes all of its features in a
clean API. See Chapter 11, Oracle VM VirtualBox Programming Interfaces.

Oracle VM VirtualBox provides a soft keyboard that
enables you to input keyboard characters on the guest. A soft
keyboard is an on-screen keyboard that can be used as an
alternative to a physical keyboard. See
Section 1.18.1, “Using the Soft Keyboard” for details of how to use the
soft keyboard.

The soft keyboard can be used in the following scenarios:

By default, the soft keyboard includes some common international
keyboard layouts. You can copy and modify these to meet your own
requirements. See Section 1.18.2, “Creating a Custom Keyboard Layout”.

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