The OpenBSD project provides a multi-platform UNIX-like operating system derived from 4.4BSD. Our goals focus on correctness, security, standards compliance and portability.
This FAQ specifically covers the then-current OpenBSD release (5.0 in the original document).
OpenBSD 5.0 runs on the following platforms (availability varies by release):
“Available on CD” indicates that the official CD set includes that platform and many packages for it. Base-system ISO images are also available for most other platforms; these are not the same as the official distribution CDs.
More information about supported platforms is available on the OpenBSD platforms page.
Support for many architectures exists simply because maintainers volunteer to support them. Supporting multiple platforms helps surface portability and design issues early; OpenBSD supports a wide variety of CPU architectures and endianness models which improves overall code quality.
New users often ask whether OpenBSD is “better” than other free UNIX-like systems; that’s a subjective debate. The reasons we consider OpenBSD useful include:
Whether OpenBSD is useful for you depends on your needs.
OpenBSD is entirely free. The binaries are free, the source is free, and every part of OpenBSD uses licensing terms that allow redistribution. That includes reusing most OpenBSD source code for personal or commercial purposes. OpenBSD imposes no restrictions beyond those in the original BSD license. Software distributed under overly restrictive licenses cannot be included in the standard OpenBSD distribution because the project wants to preserve OpenBSD’s freedom of use.
That means OpenBSD can be used freely for personal projects, education, government, nonprofits, and commercial organizations. It can also be incorporated in whole or in part into commercial products.
People sometimes ask whether it is frustrating to see OpenBSD code used in commercial products. The project position has long been that it is better for good code to be widely used than for vendors to rewrite poor, incompatible alternatives to solve problems that are already solved. SSH is a good example: its broad adoption is tied directly to the freedom of OpenSSH.
That does not mean the project rejects donations or hardware support. On the contrary, it survives largely through the time, equipment, and connectivity provided by developers and supporters.
OpenBSD is maintained by a development team spread across many countries. The project is coordinated by Theo de Raadt in Canada.
The OpenBSD team publishes a new release every six months, traditionally in May and November.
OpenBSD ships with a substantial set of third-party software, typically with local fixes for security, portability, or correctness. Examples from the original 5.0-era list include:
The OpenBSD team frequently patches third-party components to improve security or code quality. Sometimes those changes are invisible to users; sometimes they affect behavior. It is worth remembering that replacing the base version blindly with another upstream build may trade away security hardening for a newer version number.
Additional software can of course be installed through the packages and ports system.
The complete change list from OpenBSD 4.9 to 5.0 is available in the official changelog, but a few notable points highlighted by the project at the time were:
/etc/rc.d, not just packages.mac68k platform returned.bce(4) was enabled by default.grep(1) usefulness in the man tree.sparc64 and amd64.