“Linux people do what they do because they hate Microsoft. We do what we do because we love Unix."
– Theo de Raadt
The history of BSD is linked with the history of Unix. The Unix operating system first emerged in the early 70’s and it introduced a certain philosophy towards building operating systems. The Unix philosophy has withstood the test of time and can be observed in a whole range of operating systems from the biggest mainframes to the smallest computing devices. Not only are Unix based operating systems powering pretty much all of the internet in the form of web, name, mail, and caching servers, they also have an almost full monopoly on smartphones with Apple’s iOS and Google’s Android operating systems. A more in depth description of the Unix philosophy can be found below.
The Unix philosophy has been described in multiple ways. What follows are a short version by Peter H. Salus, and a more extensive version by Eric S. Raymond.
The short version:
The longer version is:
Below an image of the history of the various unix-based operating systems.
As shown in the graph above, Unix comes in many distinct flavours and one of those flavours is the Berkeley Software Distribution, or BSD for short. Separating one Unix operating system from other Unix based operating systems can be done based on the license in use, the kernel (design), user space tools, and ancestry. Inversely and as such, the various BSD distributions share a common ancester, use a BSD kernel in one form or another, use the BSD user space tools (as opposed to GNU tools), and generally use the ICS or BSD license for the code they write. The specifics of some of the BSD distributions can be found below.
The OpenBSD project produces a freely available, multi-platform 4.4BSD-based UNIX-like operating system. Their goals place emphasis on correctness, security, standardization, and portability.
Some reasons why we think OpenBSD is a useful operating system:
FreeBSD is an operating system for a variety of platforms which focuses on features, speed, and stability. It is derived from BSD, the version of UNIX® developed at the University of California, Berkeley. It is developed and maintained by a large community.
The NetBSD Project is an international collaborative effort of a large group of people, to produce a freely available and redistributable UNIX-like operating system, NetBSD. In addition to their own work, NetBSD contains a variety of other free software, including 4.4BSD Lite2 from the University of California, Berkeley.
One of the primary focuses of the NetBSD project has been to make the base OS highly portable. This has resulted in NetBSD being ported to a large number of hardware platforms. NetBSD is also interoperable, implementing many standard APIs and network protocols, and emulating many other systems’ ABIs.
HardenedBSD is a fork of FreeBSD, founded in 2014, that implements exploit mitigations and security hardening technologies. The primary goal of HardenedBSD is to perform a clean-room re-implementation of the grsecurity patchset for Linux to HardenedBSD.
HardenedBSD has successfully implemented the following features:
The licenses in use by the various BSD projects are very permissive and short enough to include in their entirety on this page.
Copyright (c) <YEAR> <OWNER> All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. * Neither the name of the University of California, Berkeley nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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