Git-Mirrors/qubes-doc
1
0
Fork 0
mirror of https://github.com/QubesOS/qubes-doc.git synced 2025-05-02 06:46:11 -04:00
Code Issues Projects Releases Packages Wiki Activity

Remove en/ directory (QubesOS/qubes-issues#1333)

Browse source
This commit is contained in:
Axon 2015-10-28 21:00:07 +00:00
parent b30b7d266b
commit 2e68758b50
No known key found for this signature in database
GPG key ID: 8CE137352A019A17
161 changed files with 0 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

119
basics/getting-started.md Normal file
View file

@ -0,0 +1,119 @@
---
layout: doc
title: Getting Started
permalink: /en/doc/getting-started/
redirect_from:
- /doc/GettingStarted/
- /wiki/GettingStarted/
---
Getting Started with Qubes OS
=============================
Note: This guide assumes that you've just installed Qubes for the first time. The installation guide for your Qubes release can be found on the [Downloads](/downloads/) page.
Now that you've installed Qubes, let's cover some basic concepts.
AppVMs (Domains) and TemplateVMs
--------------------------------
In Qubes, you run all your programs in **domains**. Domains are also called **AppVMs** because they're implemented as lightweight virtual machines (VMs). Not every app runs in its own VM. (That would be a big waste of resources!) Instead, each VM represents a *security domain* (e.g., "work," "personal," "banking," etc.). Each domain is based, by default, on a single, common **TemplateVM** (but you can create as many as you'd like). This means that when you create a new AppVM, you don't copy the whole root filesystem needed for this AppVM to work (which would include copying all the programs). Instead, each AppVM *shares* the root filesystem with its respective TemplateVM. An AppVM has read-only access to the filesystem of the Template on which it's based, so an AppVM cannot modify a TemplateVM in any way. This is important, as it means that if an AppVM is ever compromised, the TemplateVM on which it's based (and any other AppVMs based on that TemplateVM) will still be safe. This means that creating a large number of domains is cheap: Each one needs only as much disk space as is necessary to store its private files (e.g., the "home" folder).
If you've installed Qubes using the default options, a few domains have already been created for you:
- work
- personal
- untrusted
Each domain, apart from having a distinct name, is also assigned a **label**, which is one of several pre-defined colors. The trusted window manager uses these colors in order to draw window decorations (color frames) around the windows of applications running in each domain. These allow you to quickly and easily identify the trust level of a given window at a glance. It's totally up to you how you'd like to interpret these colors. Personally, I find it natural to associate red with that which is untrusted and dangerous (the “red light” -- stop! danger!), green with that which is safe and trusted, and yellow and orange with things in the middle. I've also extended this scheme to include blue and black, which I interpret as indicating progressively more trusted domains than green, with black being ultimately trusted.
![snapshot12.png](/attachment/wiki/GettingStarted/snapshot12.png)
In addition to AppVMs and TemplateVMs, there's one special domain called "dom0," which is where the Desktop Manager runs. This is where you log in to the system. Dom0 is more trusted than any other domain (including TemplateVMs and black-labeled domains). If dom0 were ever compromised, it would be Game Over<sup>TM</sup>. (The entire system would effectively be compromised.) Due to its overarching importance, dom0 has no network connectivity and is used only for running the Window and Desktop Managers. Dom0 shouldn't be used for anything else. In particular, [you should never run user applications in dom0](/en/doc/security-guidelines/#dom0-precautions). (That's what your AppVMs are for!)
Qubes VM Manager and Command Line Tools
---------------------------------------
All aspects of the Qubes system can be controlled using command line tools run under a dom0 console. To open a console window in dom0, either go to Start-\>System Tools-\>Konsole or press Alt-F2 and type `konsole`.
Various command line tools are described as part of this guide, and the whole reference can be found [here](/en/doc/dom0-tools/).
![r2b1-dom0-konsole.png](/attachment/wiki/GettingStarted/r2b1-dom0-konsole.png)
Alternatively, you can use a rather intuitive GUI tool called **Qubes VM Manager**. It supports most of the functionality that command line tools provide. The Qubes VM Manager starts and opens automatically when Qubes starts up, but you can also start it by going to Start-\>System Tools-\>Qubes Manager. Once the Qubes VM Manager is running, you can open the window at any time by clicking on the Qubes tray icon, which typically resides in the bottom-right corner of the screen.
![r2b1-qubes-manager-2.png](/attachment/wiki/GettingStarted/r2b1-qubes-manager-2.png)
Starting Apps in Domains
------------------------
Apps can be started either by using the shortcuts in the Desktop Manager's menu or by using the command line (i.e., a console running in dom0).
You can start apps directly from the start menu. Each domain has its own menu directory under the scheme **Domain: \<name\>**. After navigating into one of these directories, simply click on the application you'd like to start:
![r2b1-appsmenu-1.png](/attachment/wiki/GettingStarted/r2b1-appsmenu-1.png) ![r2b1-appsmenu-3.png](/attachment/wiki/GettingStarted/r2b1-appsmenu-3.png)
By default, each domain's menu contains only a few shortcuts. If you'd like to add more, simply click **Add more shortcuts...**, select the desired applications, and click **OK**. You can also add shortcuts manually. (This is sometimes necessary if the desired application doesn't show up in the Qubes VM Manager window.) To do this in KDE, right-click on the **Start** button and click **Menu Editor**. Click the domain directory in which you'd like the menu to appear, click **New Item**, enter its name as **\<domain name\>: \<app name\>**, and provide the command for starting the app (see below). Then click **Save** and wait approximately 15 seconds for the changes to propagate to the KDE menu.
To start apps from the console in dom0, type:
qvm-run -a <domain> "<app name> [arguments]"
e.g.:
qvm-run -a untrusted firefox
Adding, Removing, and Listing Domains
-------------------------------------
Domains can easily be added and removed by clicking on the **Add** and **Remove** buttons in the Qubes VM Manager.
Domains can also be added, removed, and listed from command line (i.e., a console running in dom0) using the following tools:
- `qvm-create`
- `qvm-remove`
- `qvm-ls`
How Many Domains Do I Need?
---------------------------
That's a great question, but there's no one-size-fits-all answer. It depends on the structure of your digital life, and this is at least a little different for everyone. If you plan on using your system for work, then it also depends on what kind of job you do.
It's a good idea to start out with the three domains created automatically by the installer: work, personal, and untrusted. Then, if and when you start to feel that some activity just doesn't fit into any of your existing domains, you can easily create a new domain for it. You'll also be able to easily copy any files you need to the newly created domain, as explained [here](/en/doc/copying-files/).
More paranoid people might find it worthwhile to read [this article](http://theinvisiblethings.blogspot.com/2011/03/partitioning-my-digital-life-into.html), which describes how one of the Qubes authors partitions her digital life into security domains.
Full Screen Domains
-------------------
By default, Qubes doesn't allow any application window to occupy the entire screen such that its window name (which includes the name of the domain to which it belongs) and colored window border are no longer visible. This is a security precaution designed to prevent a situation in which an application which has been allowed to enter full screen mode begins to emulate the entire Qubes system. We want it to be the case that the user is always able to identify which domain is displaying any given window. Otherwise, a compromised domain which is able to occupy the entire screen could trick the user into thinking that she is interacting with a variety of different domains (including dom0), when in fact she is interacting with only a single, compromised domain pretending to be the whole system.
However, if the user makes use of an "expose-like" desktop switcher, such as the "Desktop Grid" effect that is enabled by default under KDE (default activation command: Ctrl-F8), then we can safely allow domains to enter full screen mode, as we have assurance that we can always "preempt" them by hitting the magic key combination (e.g., Ctrl-F8), which will be consumed by the trusted window manager and not passed down to the fullscreen AppVM. This means that the AppVM has no way of effectively "faking" the fullscreen view of the system, as the user can easily identify it as "just another AppVM." Theoretically, this could be achieved even with primitive Alt-Tab like switching, which should be available on simpler Window Managers (such as Xfce4, which we also support as an alternative dom0 Desktop Environment), but this might be less obvious to the user.
To allow domains to enter full screen mode, one should edit the `/etc/qubes/guid.conf` file in dom0.
E.g. to allow all domains to enter full screen mode, set `allow_fullscreen` flag to `true` in the `global` section:
global: {
# default values
allow_fullscreen = false;
#allow_utf8_titles = false;
#secure_copy_sequence = "Ctrl-Shift-c";
#secure_paste_sequence = "Ctrl-Shift-v";
#windows_count_limit = 500;
};
To allow only select AppVMs to enter full screen mode, create a per-VM section, and set `allow_fullscreen` flag there to `true`:
VM: {
work: {
allow_fullscreen = true;
};
};
In order for the changes to take effect, restart the AppVM(s).
* * * * *
Now that you're familiar with the basics, please have a look at the rest of the [documentation](/en/doc/).

80
basics/intro.md Normal file
View file

@ -0,0 +1,80 @@
---
layout: doc
title: Introduction
permalink: /en/intro/
redirect_from:
- /intro/
- "/doc/SimpleIntro/"
- "/wiki/SimpleIntro/"
---
A Simple Introduction to Qubes
==============================
This is a short, non-technical introduction to Qubes intended for a popular audience. (If you just want to quickly gain a basic understanding of what Qubes is all about, you're in the right place!)
What is Qubes?
--------------
Qubes is a security-oriented operating system (OS). The OS is the software which runs all the other programs on a computer. Some examples of popular OSes are Microsoft Windows, Mac OS X, Android, and iOS. Qubes is free and open-source software (FOSS). This means that everyone is free to use, copy, and change the software in any way. It also means that the source code is openly available so others can contribute to and audit it.
Why is OS security important?
-----------------------------
Most people use an operating system like Windows or OS X on their desktop and laptop computers. These OSes are popular because they tend to be easy to use and usually come pre-installed on the computers people buy. However, they present problems when it comes to security. For example, you might open an innocent-looking email attachment or website, not realizing that you're actually allowing malware (malicious software) to run on your computer. Depending on what kind of malware it is, it might do anything from showing you unwanted advertisements to logging your keystrokes to taking over your entire computer. This could jeopardize all the information stored on or accessed by this computer, such as health records, confidential communications, or thoughts written in a private journal. Malware can also interfere with the activities you perform with your computer. For example, if you use your computer to conduct financial transactions, the malware might allow its creator to make fradulent transactions in your name.
Aren't antivirus programs and firewalls enough?
-----------------------------------------------
Unfortunately, conventional security approaches like antivirus programs and (software and/or hardware) firewalls are no longer enough to keep out sophisticated attackers. For example, nowadays it's common for malware creators to check to see if their malware is recognized by any popular antivirus programs. If it's recognized, they scramble their code until it's no longer recognizable by the antivirus programs, then send it out. The best antivirus programs will subsequently get updated once the antivirus programmers discover the new threat, but this usually occurs at least a few days after the new attacks start to appear in the wild. By then, it's typically too late for those who have already been compromised. In addition, bugs are inevitably discovered in the common software we all use (such as our web browsers), and no antivirus program or firewall can prevent all of these bugs from being exploited.
How does Qubes provide security?
--------------------------------
Qubes allows you to separate the various parts of your digital life into securely isolated virtual machines (VMs). A VM is basically a simulated computer with its own OS which runs as software on your physical computer. You can think of a VM as a *computer within a computer*. This allows you to have, for example, one VM for visiting untrusted websites and a different VM for doing online banking. This way, if your untrusted browsing VM get compromised by a malware-laden website, your online banking activities won't be at risk. Similarly, if you're concerned about risky email attachments, Qubes can make it so that every attachment gets opened in its own single-use, "disposable" VM.
In general, Qubes takes an approach called **security by isolation**, which in this context means keeping the things you do on your computer securely isolated in different VMs so that one VM getting compromised won't affect the others. This allows you to do everything on a single physical computer without having to worry about one successful cyberattack taking down your entire digital life in one fell swoop.
How does Qubes compare to using a "live CD" OS?
-----------------------------------------------
Booting your computer from a live CD (or DVD) when you need to perform sensitive activities can certainly be more secure than simply using your main OS, but this method still preserves many of the risks of conventional OSes. For example, popular live OSes (such as [Tails](https://tails.boum.org/) and other Linux distributions) are still **monolithic** in the sense that all software is still running in the same OS. This means, once again, that if your session is compromised, then all the data and activities performed within that same session are also potentially compromised.
How does Qubes compare to running VMs in a convential OS?
---------------------------------------------------------
Not all virtual machine software is equal when it comes to security. You may have used or heard of VMs in relation to software like VirtualBox or VMware Workstation. These are known as "Type 2" or "hosted" hypervisors. (The **hypervisor** is the software, firmare, or hardware that creates and runs virtual machines.) These programs are popular because they're designed primarily to be easy to use and run under popular OSes like Windows (which is called the **host** OS, since it "hosts" the VMs). However, the fact that Type 2 hypervisors run under the host OS means that they're really only as secure as the host OS itself. If the host OS is ever compromised, then any VMs it hosts are also effectively compromised.
By contrast, Qubes uses a "Type 1" or "bare metal" hypervisor called [Xen](http://www.xenproject.org). Instead of running inside an OS, Type 1 hypervisors run directly on the "bare metal" of the hardware. This means that an attacker must be capable of subverting the hypervisor itself in order to compromise the entire system, which is vastly more difficult.
Qubes makes it so that multiple VMs running under a Type 1 hypervisor can be securely used as an integrated OS. For example, it puts all of your application windows on the same desktop with special colored borders indicating the trust levels of their respective VMs. It also allows for things like secure copy/paste operations between VMs, securely copying and transferring files between VMs, and secure networking between VMs and the Internet.
How does Qubes compare to using a separate physical machine?
------------------------------------------------------------
Using a separate physical computer for sensitive activities can certainly be more secure than using one computer with a conventional OS for everything, but there are still risks to consider. Briefly, here are some of the main pros and cons of this approach relative to Qubes:
Pros:
- Physical separation doesn't rely on a hypervisor. (It's very unlikely that an attacker will break out of Qubes' hypervisor, but if she were to manage to do so, she could potentially gain control over the entire system.)
- Physical separation can be a natural complement to physical security. (For example, you might find it natural to lock your secure laptop in a safe when you take your unsecure laptop out with you.)
Cons:
- Physical separation can be cumbersome and expensive, since we may have to obtain and set up a separate physical machine for each security level we need.
- There's generally no secure way to transfer data between physically separate computers running conventional OSes. (Qubes has a secure inter-VM file transfer system to handle this.)
- Physically separate computers running conventional OSes are still independently vulnerable to most conventional attacks due to their monolithic nature.
- Malware which can bridge air gaps has existed for several years now and is becoming increasingly common.
(For more on this topic, please see the paper [Software compartmentalization vs. physical separation](http://www.invisiblethingslab.com/resources/2014/Software_compartmentalization_vs_physical_separation.pdf).)
More information
----------------
This page is just a brief sketch of what Qubes is all about, and many technical details have been omitted here for the sake of presentation.
- If you're a current or potential Qubes user, you may want to check out the [documentation](/en/doc/) and the [FAQ](/en/doc/user-faq/).
- If you're a developer, there's dedicated [documentation](/en/doc/system-doc/) and an [FAQ](/en/doc/devel-faq/) just for you.
- Ready to give Qubes a try? Head on over to the [downloads page](/downloads/).
- Once you've installed Qubes, here's a guide on [getting started](/en/doc/getting-started/).

85
basics/mailing-lists.md Normal file
View file

@ -0,0 +1,85 @@
---
layout: doc
title: Mailing Lists
permalink: /en/doc/mailing-lists/
redirect_from:
- /doc/QubesLists/
- /wiki/QubesLists/
---
Qubes Mailing Lists
===================
Please send all the questions regarding Qubes to one of the following mailing lists. **Please do not send questions to individual Qubes developers.** By sending a message to the appropriate mailing list, you are not only giving others a chance to help you, but you may also be helping others by starting a public discussion about a shared problem or interest.
Mailing List Rules
------------------
- Send your message to the correct list. Read the sections below to determine which list is correct for your message.
- Do not [top-post](https://en.wikipedia.org/wiki/Posting_style).
- Include a precise and informative subject line. This will allow others to easily find your thread in the future and use it as a reference.
- Bad: "Help! Qubes problems!"
- Good: "R2B2 Installation problem: Apple keyboard not working in installer."
- Be concise. Do not write an essay. Include only essential information. Please think about how many messages come to the list every day and whether people will want to read through your lengthy message (hint: they won't!).
- Do not apologize for your poor English. This is a waste of everyone's time, including your own. If we can't understand you, we will ask you to clarify (or ignore your message if it's a total mess ;).
- While we're generally open to hearing suggestions for new features, please note that we already have a pretty well defined [roadmap](https://github.com/QubesOS/qubes-issues/milestones), and it's rather unlikely that we will change our schedule in order to accommodate your request. If there's a particular feature you'd like to see in Qubes, a much more effective way to make it happen is to... contribute code to Qubes which implements it! We happily accept such contributions, provided they meet our standards. Please note, however, that it's always a good idea to field a discussion of your idea on the qubes-devel list before putting in a lot of hard work on something that we may not be able or willing to accept.
The `qubes-users` Mailing List
------------------------------
### How to Use This List
This list is for helping users solve various daily problems with Qubes OS. Examples of topics or questions suitable for this list include:
- [HCL reports](/doc/HCL/#generating-and-submitting-new-reports).
- Installation problems.
- Hardware compatibility problems.
- Bug reports.
- How do I...?
### Read These First
Please try searching both the Qubes website and the archives of the mailing lists before sending a question. In addition, please make sure that you have read and understood the following basic documentation prior to posting to the list:
- [Installation guides, System Requirements, and HCL](/doc/QubesDownloads/) \<-- for problems related to Qubes OS installation
- [Qubes User FAQ](/en/doc/user-faq/)
- [Qubes User Guides](/en/doc/) \<-- for questions about how to use Qubes OS
### How to Subscribe and Post
You don't have to subscribe in order to post to this list. However, subscribing might nonetheless be desirable, as it ensures that your messages will not be eaten by the Google Groups spam filter and allows you to receive messages which were sent directly to the list.
- To subscribe to the list, send a blank mail to `qubes-users+subscribe@googlegroups.com`. (Note: A Gmail account is not required. Any email address should work.)
- To post a message to the list, address your email to `qubes-users@googlegroups.com`. (Note: You don't have to be subscribed in order to post.)
- To unsubscribe, send a blank email to `qubes-users+unsubscribe@googlegroups.com`.
- This list has a Google Groups web interface: [https://groups.google.com/group/qubes-users](https://groups.google.com/group/qubes-users)
- Some users prefer to interact with the mailing list through the Google Groups web interface. This has the advantage that it allows you to search and reply to messages which were sent prior to your subscription to the list. However, a Google account is required in order to post through this interface.
The `qubes-devel` mailing list
------------------------------
### How to Use This List
This list is primarily intended for people who are interested in contributing to Qubes OS or who are willing to learn more about its architecture and implementation. Examples of topics and questions suitable for this list include:
- Questions about why we made certain architecture or implementation decisions. ("Why did you implement XYZ this way and not the other way?")
- Questions about code layout and where is code for certain functionality.
- Discussions about proposed new features, patches, etc. ("I would like to implement feature XYZ.")
- Contributed code and patches.
- Security discussions which are relevant to Qubes in some way.
### How to Subscribe and Post
You must be subscribed in order to post to this list.
- To subscribe to the list, send a blank mail to `qubes-devel+subscribe@googlegroups.com`. (Note: A Gmail account is not required. Any email address should work.)
- To post a message to the list, address your email to `qubes-devel@googlegroups.com`. (Note: You must be subscribed in order to post. If your post does not appear, please allow time for moderation to occur.)
- To unsubscribe, send a blank email to `qubes-devel+unsubscribe@googlegroups.com`.
- This list has a Google Groups web interface: [https://groups.google.com/group/qubes-devel](https://groups.google.com/group/qubes-devel)
- Some users prefer to interact with the mailing list through the Google Groups web interface. This has the advantage that it allows you to search and reply to messages which were sent prior to your subscription to the list. However, a Google account is required in order to post through this interface.

233
basics/user-faq.md Normal file
View file

@ -0,0 +1,233 @@
---
layout: doc
title: Users' FAQ
permalink: /en/doc/user-faq/
redirect_from:
- /doc/UserFaq/
- /wiki/UserFaq/
---
Qubes Users' FAQ
================
[General Questions](#general-questions)
---------------------------------------
* [Is Qubes just another Linux distribution?](#is-qubes-just-another-linux-distribution)
* [How is Qubes different from other security solutions?](#how-is-qubes-different-from-other-security-solutions)
* [What is the main concept behind Qubes?](#what-is-the-main-concept-behind-qubes)
* [What about other approaches to security?](#what-about-other-approaches-to-security)
* [What about safe languages and formally verified microkernels?](#what-about-safe-languages-and-formally-verified-microkernels)
* [Why does Qubes use virtualization?](#why-does-qubes-use-virtualization)
* [Does Qubes run every app in a separate VM?](#does-qubes-run-every-app-in-a-separate-vm)
* [Why does Qubes use Xen instead of KVM or some other hypervisor?](#why-does-qubes-use-xen-instead-of-kvm-or-some-other-hypervisor)
* [What about this other/new (micro)kernel/hypervisor?](#what-about-this-othernew-microkernelhypervisor)
* [What's so special about Qubes' GUI virtualization?](#whats-so-special-about-qubes-gui-virtualization)
* [Can I watch YouTube videos in AppVMs?](#can-i-watch-youtube-videos-in-appvms)
* [Can I run applications, like games, which require 3D support?](#can-i-run-applications-like-games-which-require-3d-support)
* [Is Qubes a multi-user system?](#is-qubes-a-multi-user-system)
* [Why passwordless sudo?](#why-passwordless-sudo)
* [How should I report documentation issues?](#how-should-i-report-documentation-issues)
[Installation & Hardware Compatibility](#installation--hardware-compatibility)
------------------------------------------------------------------------------
* [How much disk space does each AppVM require?](#how-much-disk-space-does-each-appvm-require)
* [How much memory is recommended for Qubes?](#how-much-memory-is-recommended-for-qubes)
* [Can I install Qubes on a system without VT-x?](#can-i-install-qubes-on-a-system-without-vt-x)
* [Can I install Qubes on a system without VT-d?](#can-i-install-qubes-on-a-system-without-vt-d)
* [Can I use AMD-v instead of VT-x?](#can-i-use-amd-v-instead-of-vt-x)
* [Can I install Qubes in a virtual machine (e.g., on VMWare)?](#can-i-install-qubes-in-a-virtual-machine-eg-on-vmware)
* [Why does my network adapter not work?](#why-does-my-network-adapter-not-work)
[Common Problems](#common-problems)
-----------------------------------
* [My AppVMs lost Internet access after a TemplateVM update. What should I do?](#my-appvms-lost-internet-access-after-a-templatevm-update-what-should-i-do)
* [My keyboard layout settings are not behaving correctly. What should I do?](#my-keyboard-layout-settings-are-not-behaving-correctly-what-should-i-do)
* [My dom0 and/or TemplateVM update stalls when attempting to update via …](#my-dom0-andor-templatevm-update-stalls-when-attempting-to-update-via-the-gui-tool-what-should-i-do)
* [How do I run a Windows HVM in non-seamless mode (i.e., as a single window)?](#how-do-i-run-a-windows-hvm-in-non-seamless-mode-ie-as-a-single-window)
* [I created a usbVM and assigned usb controllers to it. Now the usbVM wont boot.](#i-created-a-usbvm-and-assigned-usb-controllers-to-it-now-the-usbvm-wont-boot)
* [I assigned a PCI device to an AppVM, then unassigned it/shut down the …](#i-assigned-a-pci-device-to-an-appvm-then-unassigned-itshut-down-the-appvm-why-isnt-the-device-available-in-dom0)
-----------------
General Questions
-----------------
### Is Qubes just another Linux distribution?
If you really want to call it a distribution, then it's more of a "Xen distribution" than a Linux one. But Qubes is much more than just Xen packaging. It has its own VM management infrastructure, with support for template VMs, centralized VM updating, etc. It also has a very unique GUI virtualization infrastructure.
### How is Qubes different from other security solutions?
Please see [this article](http://theinvisiblethings.blogspot.com/2012/09/how-is-qubes-os-different-from.html) for a thorough discussion.
### What is the main concept behind Qubes?
To build security on the “Security by Isolation” principle.
### What about other approaches to security?
The other two popular [approaches](http://theinvisiblethings.blogspot.com/2008/09/three-approaches-to-computer-security.html) are “Security by Correctness” and “Security by Obscurity.” We don't believe either of these approaches are capable of providing reasonable security today, nor do we believe that they will be capable of doing so in the foreseeable future.
### What about safe languages and formally verified microkernels?
In short: these are non-realistic solutions today. We discuss this in further depth in our [Architecture Specification document](/attachment/wiki/QubesArchitecture/arch-spec-0.3.pdf).
### Why does Qubes use virtualization?
We believe that this is currently the only practically viable approach to implementing strong isolation while simultaneously providing compatibility with existing applications and drivers.
### Does Qubes run every app in a separate VM?
No! This would not make much sense. Qubes uses lightweight VMs to create security domains (e.g., "work," "personal," and "banking,"). A typical user would likely need around five domains. Very paranoid users, or those who are high-profile targets, might use a dozen or more domains.
### Why does Qubes use Xen instead of KVM or some other hypervisor?
In short: we believe the Xen architecture allows for the creation of more secure systems (i.e. with a much smaller TCB, which translates to a smaller attack surface). We discuss this in much greater depth in our [Architecture Specification document](/attachment/wiki/QubesArchitecture/arch-spec-0.3.pdf).
### What about this other/new (micro)kernel/hypervisor?
Whenever starting a discussion about another (micro)kernel or hypervisor in relation to Qubes, we strongly suggest including answers to the following questions first:
1. What kinds of containers does it use for isolation? Processes? PV VMs? Fully virtualized VMs (HVMs)? And what underlying h/w technology is used (ring0/3, VT-x)?
2. Does it require specially written/built applications (e.g. patched Firefox)?
3. Does it require custom drivers, or can it use Linux/Windows ones?
4. Does it support VT-d, and does it allow for the creation of untrusted driver domains?
5. Does it support S3 sleep?
6. Does it work on multiple CPUs/Chipsets?
7. What are the performance costs, more or less? (e.g. "XYZ prevents concurrent execution of two domains/processes on shared cores of a single processor", etc.)
8. Other special features? E.g. eliminates cooperative covert channels between VMs?
Here are the answers for Xen 4.1 (which we use as of 2014-04-28):
1. PV and HVM Virtual Machines (ring0/3 for PV domains, VT-x/AMD-v for HVMs).
2. Runs unmodified usermode apps (binaries).
3. Runs unmodified Linux drivers (dom0 and driver domains). PV VMs require special written pvdrivers.
4. Full VT-d support including untrusted driver domains.
5. S3 sleep supported well.
6. Works on most modern CPUs/Chipsets.
7. Biggest performance hit on disk operations (especially in Qubes when complex 2-layer mapping used for Linux AppVMs). No GPU virtualization.
8. Mostly Works<sup>TM</sup> :)
### What's so special about Qubes' GUI virtualization?
We have designed the GUI virtualization subsystem with two primary goals: security and performance. Our GUI infrastructure introduces only about 2,500 lines of C code (LOC) into the privileged domain (Dom0), which is very little, and thus leaves little space for bugs and potential attacks. At the same time, due to the smart use of Xen shared memory, our GUI implementation is very efficient, so most virtualized applications really feel as if they were executed natively.
### Can I watch YouTube videos in AppVMs?
Absolutely.
### Can I run applications, like games, which require 3D support?
Those won’t fly. We do not provide OpenGL virtualization for AppVMs. This is mostly a security decision, as implementing such a feature would most likely introduce a great deal of complexity into the GUI virtualization infrastructure. However, Qubes does allow for the use of accelerated graphics (OpenGL) in Dom0’s Window Manager, so all the fancy desktop effects should still work.
For further discussion about the potential for GPU passthorugh on Xen/Qubes, please see the following threads:
- [GPU passing to HVM](https://groups.google.com/group/qubes-devel/browse_frm/thread/31f1f2da39978573?scoring=d&q=GPU&)
- [Clarifications on GPU security](https://groups.google.com/group/qubes-devel/browse_frm/thread/31e2d8a47c8b4474?scoring=d&q=GPU&)
### Is Qubes a multi-user system?
No. Qubes does not pretend to be a multi-user system. Qubes assumes that the user who controls Dom0 controls the whole system. It would be very difficult to **securely** implement multi-user support. See [here](https://groups.google.com/group/qubes-devel/msg/899f6f3efc4d9a06) for details.
### Why passwordless sudo?
Please refer to [this page](https://www.qubes-os.org/doc/VMSudo/).
### How should I report documentation issues?
Create an issue in [qubes-issues](https://github.com/QubesOS/qubes-issues/issues), but **please make sure your issue does not already exist**. Documentation-related issues will be assigned the `doc` label. Issues which have been created in `qubes-issues` are significantly more likely to be addressed than those sent in emails to the mailing lists.
Installation & Hardware Compatibility
-------------------------------------
(See also: [System Requirements](/en/doc/system-requirements/) and [Hardware Compatibility List](/hcl/).)
### How much disk space does each AppVM require?
Each AppVM is created from a TemplateVM and shares the root filesystem with this TemplateVM (in a read-only manner). This means that each AppVM needs only as much disk space as is necessary to store its own private data. This also means that it is possible to update the software for several AppVMs simultaneously by running a single update process in the TemplateVM upon which those AppVMs are based. (These AppVMs will then have to be restarted in order for the update to take effect in them.)
### How much memory is recommended for Qubes?
At least 4 GB. It is possible to install Qubes on a system with 2 GB of RAM, but the system would probably not be able to run more than three AppVMs at a time.
### Can I install Qubes on a system without VT-x?
Yes. Xen doesn't use VT-x (or AMD-v) for PV guest virtualization. (It uses ring0/3 separation instead.) However, without VT-x, you won't be able to use fully virtualized VMs (e.g., Windows-based AppVMs), which were introduced in Qubes 2. In addition, if your system lacks VT-x, then it also lacks VT-d. (See next question.)
### Can I install Qubes on a system without VT-d?
Yes. You can even run a NetVM, but you will not benefit from DMA protection for driver domains. On a system without VT-d, everything should work in the same way, except there will be no real security benefit to having a separate NetVM, as an attacker could always use a simple DMA attack to go from the NetVM to Dom0. **Nonetheless, all of Qubes' other security mechanisms, such as AppVM separation, work without VT-d. Therefore, a system running Qubes will still be significantly more secure than one running Windows, Mac, or Linux, even if it lacks VT-d.**
### Can I use AMD-v instead of VT-x?
See [this message](http://groups.google.com/group/qubes-devel/msg/6412170cfbcb4cc5).
### Can I install Qubes in a virtual machine (e.g., on VMWare)?
Some users have been able to do this, but it is neither recommended nor supported. Qubes should be installed bare-metal. (After all, it uses its own bare-metal hypervisor!)
### Why does my network adapter not work?
You may have an adapter (wired, wireless), that is not compatible with open-source drivers shipped by Qubes. There may be a binary blob, which provides drivers in the linux-firmware package.
Open a terminal and run `sudo yum install linux-firmware` in the TemplateVM upon which your NetVM is based. You have to restart the NetVM after the TemplateVM has been shut down.
Common Problems
---------------
### My AppVMs lost Internet access after a TemplateVM update. What should I do?
Run `systemctl enable NetworkManager-dispatcher.service` in the TemplateVM upon which your NetVM is based. You may have to reboot afterward for the change to take effect. (Note: This is an upstream problem. See [here](https://bugzilla.redhat.com/show_bug.cgi?id=974811). For details, see the qubes-users mailing list threads [here](https://groups.google.com/d/topic/qubes-users/xPLGsAJiDW4/discussion) and [here](https://groups.google.com/d/topic/qubes-users/uN9G8hjKrGI/discussion).)
### My keyboard layout settings are not behaving correctly. What should I do?
Please read [this disccusion](https://groups.google.com/d/topic/qubes-devel/d8ZQ_62asKI/discussion).
### My dom0 and/or TemplateVM update stalls when attempting to update via the GUI tool. What should I do?
This can usually be fixed by updating via the command line.
In dom0, open a terminal and run `sudo qubes-dom0-update`.
In your TemplateVMs, open a terminal and run `sudo yum upgrade`.
### How do I run a Windows HVM in non-seamless mode (i.e., as a single window)?
Enable "debug mode" in the AppVM's settings, either by checking the box labelled "Run in debug mode" in the Qubes VM Manager AppVM settings menu or by running the [qvm-prefs command](/en/doc/dom0-tools/qvm-prefs/).)
### I created a usbVM and assigned usb controllers to it. Now the usbVM wont boot.
This is probably because one of the controllers does not support reset. In Qubes R2 any such errors were ignored but in Qubes R3.0 they are not.
A device that does not support reset is not safe and generally should not be assigned to a VM.
Most likely the offending controller is a USB3.0 device. You can remove this controller from the usbVM, and see if this allows the VM to boot.
Alternatively you may be able to disable USB 3.0 in the BIOS.
Another solution would be to set the pci_strictreset option using qvm-prefs in dom0:
`qvm-prefs usbVM -s pci_strictreset false`
This option allows the VM to ignore the error and the VM will start.
Please review the note on [this page](https://www.qubes-os.org/doc/Dom0Tools/QvmPrefs/) and be aware of the potential risk.
### I assigned a PCI device to an AppVM, then unassigned it/shut down the AppVM. Why isn't the device available in dom0?
This is an intended feature. A device which was previously assigned to a less trusted AppVM could attack dom0 if it were automatically reassigned there. In order to re-enable the device in dom0, either:
1. Reboot the physical machine.
or
1. Go to the sysfs (`/sys/bus/pci`), find the right device, detach it from the pciback driver and attach back to the original driver. Replace `<BDF>` with your device, for example `00:1c.2`:
echo 0000:<BDF> > /sys/bus/pci/drivers/pciback/unbind
MODALIAS=`cat /sys/bus/pci/devices/0000:<BDF>/modalias`
MOD=`modprobe -R $MODALIAS | head -n 1`
echo <BDF> > /sys/bus/pci/drivers/$MOD/bind