What others are saying
"SecureDrop depends on Qubes OS for best-in-class isolation of sensitive workloads on journalist workstations. Providing journalists with a sane way to handle untrusted content from unknown sources is part of our job, and Qubes gives us the tools we need to do that job well."
"I am so much happier and less stressed out after switching to Qubes OS. Can wholeheartedly recommend."
"Qubes OS gives us greater confidence in the security of systems being used to remotely access our servers, mainly because powerful physical and logical privilege separation between workspaces allows our engineers to select appropriate degrees of isolation for different processes."
Media & Press
News & Announcements
- XSAs released on 2022-11-08 Posted in Security on 2022-11-08
- QSB-086: Speculative security issues on AMD CPUs (XSA-422) Posted in Security on 2022-11-08
- XSAs released on 2022-11-01 Posted in Security on 2022-11-01
- QSB-085: Xenstore: Guests can crash xenstored (XSA-414) Posted in Security on 2022-11-01
- New user guide: How to organize your qubes Posted in Articles on 2022-10-28
- XSAs released on 2022-10-11 Posted in Security on 2022-10-11
- The Qubes OS Project is now accepting donations on Ethereum! Posted in Announcements on 2022-09-29
- More News & Announcements
What's Inside of Qubes?
Secure Compartmentalization
Qubes brings to your personal computer the security of the Xen hypervisor, the same software relied on by many major hosting providers to isolate websites and services from each other. Learn more
Operating System Freedom
Can't decide which Linux distribution you prefer? Still need that one Windows program for work? With Qubes, you're not limited to just one OS. Learn more
Serious Privacy
With Whonix integrated into Qubes, using the Internet anonymously over the Tor network is safe and easy. Learn more
Research
- Qubes virtual mini-summit 2021 3mdeb and the Qubes team, August 2021
- Qubes Air: Generalizing the Qubes Architecture Joanna Rutkowska, January 2018
- Introducing the Next Generation Qubes Core Stack Joanna Rutkowska, October 2017
- Introducing the Qubes Admin API Joanna Rutkowska, June 2017
- Thoughts on the "physically secure" ORWL computer Joanna Rutkowska, September 2016
- Security challenges for the Qubes build process Joanna Rutkowska, May 2016
- Read More Research
Awards & Grants
Join the Community!
Have questions or need a hand? As a free and open-source project, our valued community of users and contributors from around the world are in the best position to help. Before diving in, we encourage you to read about staying safe, our discussion guidelines, and our code of conduct to help keep things positive and on-track. We welcome newcomers and returning users wanting to discuss Qubes and seeking to contribute.
A host OS is the software installed on a computer that interacts with the underlying hardware and is usually used to describe an operating system used in a virtualized server to differentiate it from the guest operating system.
A host OS is most commonly used to describe the operating system that interacts with the hardware and runs a Type 2 hypervisor. A Type 2 hypervisor, also known as a hosted hypervisor, runs on top of a host operating system rather than interacting directly with the hardware. This Type 2 hypervisor can then create multiple virtual machines (VMs) that will each run a guest operating system. In this case, guest operating systems do not need to be the same as the host OS.
Let's consider a practical example of a computer running Apple's OS X operating system. If a user wanted to run an application available only for Windows operating systems, the user may use virtualization and install a Type 2 hypervisor, such as VMware Fusion, on the computer running OS X. The user could then use the VMware Fusion hypervisor to create a VM and install Windows 10 as the operating system on that VM. The user would then be able to run his or her Windows application within this VM. The original instance of OS X installed on the computer would be considered the host operating system, while Windows 10 (running on the VM) would be considered the guest operating system.
However, not all virtualized servers make use of a host operating system. In many cases, a Type 1 hypervisor, also known as a bare-metal hypervisor, is installed directly onto a server's hardware. The Type 1 hypervisor takes the place of the host OS and can then create virtual machines, each of which may run a guest operating system.
The term host operating system can also be used to describe the operating system that makes use of container-based virtualization. Containers are essentially logical partitions used to separate applications on the same server. Rather than replicate an entire operating system for each application, as is the case in a VM, containers allow applications on the same server to share the same operating system kernel but still provide hardware isolation. This shared operating system is known as the host OS.
Server administrators may also run into the confusing situation in which a VM's guest operating system also serves as the host operating system for a container. For example, consider a server running VMware's ESXi Type 1 hypervisor that hosts a VM running a Linux distribution as the guest OS. The Linux guest OS could then be used to create multiple containers that would share the Linux OS kernel, which could therefore be considered a host OS.
This was last updated in February 2016
Continue Reading About Host OS (host operating system)
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