ServersBeyond The Big Three BSDs, BSD Alternatives

Beyond The Big Three BSDs, BSD Alternatives

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Although Linux gets much of the attention in the Free and open source operating system world, the BSD operating system is also very popular. BSD has a longer history, and its roots go right back to one of the original Unix implementations that spawned commercial Unix variants like Solaris and Mac OS X.

When FreeBSD, NetBSD, and OpenBSD don’t fit the bill, venturing beyond them may be the answer. We look at 10 not-so-well-known flavors worthy of consideration.

BSD is actually a popular source for server-focused operating systems and, due to an open license, it is sometimes more attractive to developers as the base for their projects. With some BSD variants, security and high-performance networking are key drivers.

When our last article on BSD (“Differentiating Among the BSD Distros” ran, various readers pointed out our neglect of some of the lesser-known BSD-based flavors available. This article, therefore, will look at some of the less-mainstream, yet equally valuable, BSD variants available.

We apologize in advance for any variants that don’t get mentioned in the piece. For coverage in future articles, please contact the author through the feedback form.

DragonFly BSD

The DragonFly BSD operating system is a fork of the main FreeBSD 4.x operating system.It was produced by Matt Dillon, who felt the development direction (particularly threading and SMP choices) of FreeBSD 5 would result in bad performance. DragonFly BSD is being developed with a different threading model and messaging system from those used in FreeBSD 5. Many of the concepts of DragonFly BSD have been inspired by functionality in AmigaOS. Interestingly, despite the split from the FreeBSD roots, the groups are sharing bug fixes and device drivers.

DragonFly BSD is provided as a Live CD and will boot into a fully functional DragonFly BSD system. Unlike pure Live CD products, however, it can also install DragonFly BSD. More information is available on the DragonFly BSD project page.


The MirOS project is more than just another flavor of the BSD, although it is a derivative of OpenBSD and NetBSD. It also borrows heavily from other operating systems, including Darwin (the foundation of Mac OS X), FreeBSD, and GNU/Linux. Officially, the BSD variant is called MirOS BSD (rather than MirBSD), but other variants such as MirOS Linux are also in development.

MirOS’ focus is on producing a compact and stable server operating system, with additional support and functionality for developer workstations. One of the key areas of functionality is in the communication server market where compact operating systems are often required to run on comparatively low-powered hardware. Unlike other BSD variants, the focus is not on trying to replace the more typical workstation environments of Windows or even Linux.


The TrustedBSD project combines the core FreeBSD release with trusted security components that conform to the Common Criteria for Information Technology Security Evaluation. These components provide a range of different security constructs vital to ensuring the secure operation of the operating system.

The tools include, but are certainly not limited to, centralized policy management, extensive auditing of components and execution (including kernel modules and function calls), mandatory access control for different areas of the system, and access control lists from the file system and kernel resources. Together, they provide a finer level of access control, better reporting and monitoring, and, overall, a more secure environment for running services.

The ultimate aim is to roll back the content of TrustedBSD into the main FreeBSD releases. Until then, consider them very separate projects, with the TrustedBSD project page containing downloads and documentation on the TrustedBSD implementation.


The main BSD operating systems (NetBSD, FreeBSD, and OpenBSD) are not really designed with desktop users in mind. Although they can be used as desktop operating systems, their main focus remains the provision of services as network or application server. PC BSD is different, as its focus is on a desktop-oriented (personal computing) operating system with all the functionality, stability, and performance of BSD, but with a tool set and environment that reflects a more personal environment.

To achieve this, PC BSD is based on FreeBSD with additional software to provide an environment that addresses the concerns of a typical desktop user. Although there is no delineation between business and home users, the developers do not want to limit or restrict the power of the underlying Unix-based operating system from the user in the process. A number of rules are followed to support this approach, including the requirement for easy installation and removal of software, backward compatibility without restricting new functionality, and a low-overhead approach that keeps the size of the operating system and its requirements to a minimum.

So far the approach has worked: PC BSD is a very nice operating system for those looking for a desktop operating system with a BSD core. It is friendlier than many Linux alternatives, and, unlike Linux, the entire operating system fits onto a single CD for installation. This compares well to the two to four CDs often required in a typical Linux install.

More information is available on the PC BSD page, including screen shots of the installation and package management process.

>> More BSD Flavors

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