* [Will Qubes seek to get certified on the GNU Free System Distribution Guidelines (GNU FSDG)?](#will-qubes-seek-to-get-certified-under-the-gnu-free-system-distribution-guidelines-gnu-fsdg)
* [Can I install Qubes OS together with other operating system (dual-boot/multi-boot)?](#can-i-install-qubes-os-together-with-other-operating-system-dual-bootmulti-boot)
* [My qubes lost Internet access after a TemplateVM update. What should I do?](#my-qubes-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 a qube, then unassigned it/shut down the …](#i-assigned-a-pci-device-to-a-qube-then-unassigned-itshut-down-the-qube-why-isnt-the-device-available-in-dom0)
* [How do I install Flash in a Debian qube?](#how-do-i-install-flash-in-a-debian-qube)
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.
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.
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).
We believe that this is currently the only practically viable approach to implementing strong isolation while simultaneously providing compatibility with existing applications and drivers.
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.
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.
We do not provide OpenGL virtualization for Qubes.
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.
This website is hosted via GitHub Pages behind Cloudflare ([why?](#why-does-this-website-use-cloudflare)).
Therefore, it is largely outside of our control.
We don't consider this a problem, however, since we explicitly [distrust the infrastructure](#what-does-it-mean-to-distrust-the-infrastructure).
For this reason, we don't think that anyone should place undue trust in the live version of this site on the Web.
Instead, if you want to obtain your own, trustworthy copy of this website in a secure way, you should clone our [website repo](https://github.com/QubesOS/qubesos.github.io), [verify the PGP signatures on the commits and/or tags](/doc/verifying-signatures/#verifying-qubes-code) (signed by the [doc-signing keys](https://github.com/QubesOS/qubes-secpack/tree/master/keys/doc-signing)), then either [render the site on your local machine](https://github.com/QubesOS/qubesos.github.io/blob/master/README.md#instructions) or simply read the source, the vast majority of which was [intentionally written in Markdown so as to be readable as plain text for this very reason](/doc/doc-guidelines/#markdown-conventions).
We've gone to special effort to set all of this up so that no one has to trust the infrastructure and so that the contents of this website are maximally available and accessible.
A core tenet of the Qubes philosophy is "distrust the infrastructure," where "the infrastructure" refers to things like hosting providers, CDNs, DNS services, package repositories, email servers, PGP keyservers, etc.
As a project, we focus on securing endpoints instead of attempting to secure "the middle" (i.e., the infrastructure), since one of our primary goals is to free users from being forced to entrust their security to unknown third parties.
Instead, our aim is for users to be required to trust as few entities as possible (ideally, only themselves and any known persons whom they voluntarily decide to trust).
Users can never fully control all the infrastructure they rely upon, and they can never fully trust all the entities who do control it.
Therefore, we believe the best solution is not to attempt to make the infrastructure trustworthy, but instead to concentrate on solutions that obviate the need to do so.
We believe that many attempts to make the infrastructure appear trustworthy actually provide only the illusion of security and are ultimately a disservice to real users.
Since we don't want to encourage or endorse this, we make our distrust of the infrastructure explicit.
Also see: [Should I trust this website?](#should-i-trust-this-website)
### Why does this website use Cloudflare?
Three main reasons:
1. We [distrust the infrastructure](#what-does-it-mean-to-distrust-the-infrastructure), including Cloudflare.
2. It's free (as in beer). We'd have to spend either time or money to implement a solution ourselves or pay someone to do so, and we can't spare either one right now.
3. It has low admin/overhead requirements, which is very important, given how little time we have to spare.
Also see: [Should I trust this website?](#should-i-trust-this-website)
### Why doesn't this website have security feature X?
Although we caution users against [placing undue trust in this website](#should-i-trust-this-website) because we [distrust the infrastructure](#what-does-it-mean-to-distrust-the-infrastructure), we have no objection to enabling website security features when doing so is relatively costless and provides some marginal benefit to website visitors (e.g., HTTPS via Cloudflare page rules).
So, if feature X isn't enabled, it's most likely for one of three reasons:
1. Our GitHub Pages + Cloudflare platform doesn't support it.
2. Our platform supports it, but we've decided not to enable it.
3. Our platform supports it, but we're not aware that we can enable it or have forgotten to do so.
Each qube is created from a TemplateVM and shares the root filesystem with this TemplateVM (in a read-only manner).
This means that each qube 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 qubes simultaneously by running a single update process in the TemplateVM upon which those qubes are based.
(These qubes will then have to be restarted in order for the update to take effect in them.)
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 qube 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.**
Without VT-d, any PCI device can access all the memory, regardless to which VM it is assigned (or if it is left in dom0).
Most PCI devices allow the driver to request an arbitrary DMA operation (like "put received network packets at this address in memory", or "get this memory area and send it to the network").
So, without VT-d, it gives unlimited access to the whole system.
Now, it is only a matter of knowing where to read/write to take over the system, instead of just crashing.
But since you can read the whole memory, it isn't that hard.
Now, how does this apply to Qubes OS?
The above attack requires access to a PCI device, which means that it can be performed only from NetVM / UsbVM, so someone must first break into one of those VMs.
But this isn't that hard, because there is a lot of complex code handling network traffic.
Recent bugs includes DHCP client, DNS client, etc.
Most attacks on NetVM / UsbVM (but not all!) require being somewhat close to the target system - for example connected to the same WiFi network, or in the case of a UsbVM, having physical acccess to a USB port.
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!)
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.
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).)
Enable "debug mode" in the qube's settings, either by checking the box labeled "Run in debug mode" in the Qubes VM Manager qube settings menu or by running the [qvm-prefs command](/doc/dom0-tools/qvm-prefs/).)
* 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`:
