Glossary

Primary

Primary
Qubes OS

A security-oriented operating system (OS). The main principle of Qubes OS is security by compartmentalization (or isolation), in which activities are compartmentalized (or isolated) in separate qube.

  • Important: The official name is “Qubes OS” (note the capitalization and the space between “Qubes” and “OS”). In casual conversation, this is often shortened to “Qubes”. Only in technical contexts where spaces are not permitted (e.g., in usernames) may the space be omitted, as in @QubesOS.

Compartment nomenclature

Compartment nomenclature
qube

A secure compartment in Qubes OS. Currently, qubes are implemented as Xen domain, but Qubes OS is independent of its underlying compartmentalization technology. VMs could be replaced with a different technology, and qubes would still be called “qubes”. Therefore, always opt for the term qube over the other terms unless explicitly guided otherwise.

  • Important: The term “qube” is a common noun and should follow the capitalization rules of common nouns. For example, “I have three qubes” is correct, while “I have three Qubes” is incorrect. Note that starting a sentence with the plural of “qube” (i.e., “Qubes …”) can be ambiguous, since it may not be clear whether the referent is a plurality of qubes or Qubes OS.

  • Example usage: Bank in your banking qube and web surf in your untrusted qube. That way, if your untrusted qube is compromised, your banking activities remains secure.

  • Historical note: The term “qube” was originally invented as an alternative to “VM” intended to make it easier for less technical users to understand Qubes OS and learn how to use it.

domain

In Xen, a synonym for vm. See “domain” on the Xen Wiki. This term has no official meaning in Qubes OS.

VM

An abbreviation for “virtual machine”. A software implementation of a computer that provides the functionality of a physical machine.

Qube’s types

Qube’s types
admin qube

A type of qube used for administering Qubes OS.

  • Currently, the only admin qube is dom0.

app qube

Any qube that does not have a root filesystem of its own. Every app qube is based on a template from which it borrows the root filesystem.

  • Previously known as: AppVM, TemplateBasedVM.

  • Historical note: This term originally meant “a qube intended for running user software applications” (hence the name “app”).

disposable

A disposable is a stateless qube, it does not save data for the next boot. These qubes can serve various uses cases that require a pristine environment. See How to use disposables.

  • Previously known as: DisposableVM, DispVM.

standalone

Any qube that has its own root filesystem and does not share it with another qube. Distinct from both template and app qube.

See Standalones and HVMs.

  • Previously known as: StandaloneVM.

template

Any qube that shares its root filesystem with another qube. A qube that is borrowing a template’s root filesystem is known as an app qube and is said to be “based on” the template. Templates are intended for installing and updating software applications, but not for running them.

See Templates.

  • No template is an app qube.

  • A template cannot be based on another template.

  • Regular templates cannot function as disposable template. (Disposable templates must be app qubes).

  • Previously known as: TemplateVM.

Qube’s types variations

Qube’s types variations
disposable template

Any app qube on which disposable are based. A disposable template shares its user directories (and, indirectly, the root filesystem of the regular template on which it is based) with all disposable based on it.

  • Not to be confused with the concept of a regular template that is itself disposable, which does not exist in Qubes OS.

  • Disposable templates must be app qubes. They cannot be regular template.

  • Every disposable is based on a disposable template, which is in turn based on a regular template.

  • Unlike disposable, disposable templates have the persistence properties of normal app qube.

  • Previously known as: DisposableVM Template, DVM Template, DVM. It is advised against the use of the DVM terms as it can be interpreted by some users as an abbreviation of DispVM, which a DVM is not.

named disposable

A type of disposable given a permanent name that continues to exist even after it is shut down and can be restarted again.

  • Only one instance of a named disposable can run at a time.

  • Technical note: Named disposables are useful for certain service qubes, where the combination of persistent device assignment and ephemeral qube state is desirable.

unnamed disposable

A type of disposable with a temporary name that ceases to exist after the qube is shut down. Closing the first application that was opened in the disposable will trigger the qube to shut down. Thus, if there is not initial application, such is the case with Qubes Devices widget, the qube has to be manually turned off.

  • Multiple instances of a unnamed disposable can run at a time.

  • Technical note: Named disposables are useful for certain converting, viewing and editing untrusted files, where the combination of opening multiple files in disposable qubes that you don’t need to remember their name for long is desirable.

management qube

A qube used for automated management of a Qubes OS installation via Salt (management software).

net qube

Internally known as qube that specifies from which qube, if any, it receives network access. Despite the name, “net qube” (or app qube to be the service qube sys-firewall, which in turn uses sys-net as its net qube.

  • If a qube does not have a net qube (i.e., its netvm is set to None), then that qube is offline. It is disconnected from all networking.

  • The name service qube called a “NetVM”. The name of the netvm property is a holdover from that era.

service qube

Any app qube with the primary purpose of which is to provide services to other qubes. sys-net and sys-firewall are examples of service qubes.

internal qube

A qube which has the internal feature set. Used for the management qube and preloaded disposables. These qubes are hidden from most Qubes OS graphical applications, as they are not intended to be used directly.

GUI domain

The GUI domain handles all the display-related tasks and some system management. There can be multiple GUI domains present on the system. Every GUI domain can have its own set of privileges, permissions, managed qubes etc. By default, dom0 is the only GUI domain.

Miscellaneous

Miscellaneous
dom0

domain zero. A type of admin qube. Also known as the host domain, dom0 is the initial qube started by the Xen hypervisor on boot. Dom0 runs the Xen management toolstack and has special privileges relative to other domains, such as direct access to most hardware.

  • The term “dom0” is a common noun and should follow the capitalization rules of common nouns.

domU

Unprivileged domain. Also known as guest domains, domUs are the counterparts to dom0. In Xen, all VMs except dom0 are domUs. By default, most domUs lack direct hardware access.

  • The term “domU” is a common noun and should follow the capitalization rules of common nouns.

  • Sometimes the term vm is used as a synonym for domU. This is technically inaccurate, as dom0 is also a VM in Xen.

HVM

Hardware-assisted Virtual Machine. Any fully virtualized, or hardware-assisted, vm utilizing the virtualization extensions of the host CPU. Although HVMs are typically slower than paravirtualized qubes due to the required emulation, HVMs allow the user to create domains based on any operating system.

See Standalones and HVMs.

firmware

Software that runs outside the control of the operating system. Some firmware executes on the same CPU cores as Qubes OS does, but all computers have many additional processors that the operating system does not run on, and these computers also run firmware.

policies

In Qubes OS, “policies” govern interactions between qubes, powered by Qubes’ qrexec system. A single policy is a rule applied to a qube or set of qubes, that governs how and when information or assets may be shared with other qubes. An example is the rules governing how files can be copied between qubes. Policy rules are grouped together in files under /etc/qubes/policy.d Policies are an important part of what makes Qubes OS special.

Qubes Windows Tools (QWT)

A set of programs and drivers that provide integration of Windows qubes with the rest of the Qubes OS system.

See Qubes Windows Tools (QWT) and How to install Windows qubes in Qubes OS.