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BSD - The Unix-like operating system for all of us

BSD is an abbreviated name for the Berkeley Software Distribution, a Unix derivative developed and distributed by the University of California, Berkeley. BSD was originally based on original Sixth Edition Unix code released by AT&T in 1975. Today, BSD is most generally known as a family of Open Source operating system projects derived from the original BSD sources, which are freely available to use and distribute. There are a number of flavors of BSD in use today, the most popular of which are:

BSD in relation to other Unix-like operating systems

The most obvious availability of Unix today is in the number of offerings from companies who license and distribute commercial Unix operating systems for profit. Unix is synonymous with high performance, high scalability, and high reliability. Today, Unix powers computer networks and applications for countless corporations and organizations.

Today's BSD operating systems are Unix derivatives which are developed and released under the BSD license, one of the most open and permissive of all software licenses available today. Similar operating system projects use open source licenses as well. A good example of this is the popular GPL-licensed GNU/Linux operating system distributions, based on the Linux kernel developed by Linus Torvalds and distributed with many different utilities produced by the GNU project and other sources. While GNU/Linux and modern BSD systems share many similarities in terms of capabilities, development models, and application support, there are some important aspects which differentiate the platforms:

  • Heritage. BSD Unix is a derivative of the original AT&T Unix, and has a mature history extending back to the original Unix roots. The first BSD release happened in late 1977. In contrast, the Linux kernel and GNU utilities are publicized as Unix "alternatives" or "clones", and they don't have the same benefits of long development, use and improvement.
  • Power. BSD has been a long time favorite of systems designers, computer scientists, and sysadmins for years. The level of experience of the average BSD developer and user is typically higher than with other Unix-like operating systems and as such, there has been less interest in producing a user-friendly GUI interface or effort in making the system easy for all classes of users.
  • Quality. In comparison with other popular operating systems, BSD tends to place less emphasis on supporting the latest and greatest features, applications, and hardware. While support for the greatest majority of hardware and applications is still good under modern BSDs, new features seldom ever take higher priority than code quality, stability, and overall security of the system.
  • Integrated. BSD operating systems are complete, self contained operating system environments. GNU/Linux systems are based on the idea of a distribution of the Linux kernel, bundled with a collection of userland utilities which vary from distribution to distribution. The BSD model offers a complete operating system with close integration of kernel and userland, and each BSD project ships their system with a full collection of integrated compiler toolkits, scripted language support, network services such as email, web, FTP and other miscellaneous services, and numerous other tools and utilities. This model also results in support and improvements to the operating system being handled by one centralized, cooperatively focused body of developers and contributors that work on the system as a congruent whole.
  • Free as in free. BSD systems distributed under the BSD license are free to use for commercial applications, as a basis for closed source binary applications, and do not require that improvements or modifications made to the system be released to the public under the same license. For this reason, BSD is a popular choice for software designers intending to produce commercial applications and those that are interested in pure, unrestricted software use, reuse and distribution.
  • Portable. BSD can run on a wider array of hardware platforms than any other Unix variant, and supports the following CPU architectures and more: alpha, amd64, arm, hppa, i386, m68k, powerpc, sparc, sparc64, vax, and zaurus.
  • Simplicity. The BSD community sees far less publicity and media hype in the press than other open source circles. BSD has no drive for world domination and there is little desire to spin up commercial projects selling "Enterprise" versions of a BSD platform. The user community feels little need to engage in evangelical missions to indoctinate users of other operating systems into using BSD; the quality of a BSD project speaks for itself.

Where BSD is used today

BSD software is found in many products and applications today. Thanks to its excellent support for networking applications and performance, solid security, and the openness of the license it is distributed under, BSD is used for several network security platforms and is the basis for a number of commercial Unix operating systems in wide use today:

  • Juniper Network's JUNOS, used on their M, T, and J line of routers, is based on BSD. JUNOS powers some of the most powerful routers used for Internet backbones and corporate networks today.
  • Nokia's IPSO (IP Security Operating system) is based on BSD. IPSO is the operating system platform used on Nokia's line of security appliances and has been the most popular target platform for Check Point's FW-1 and VPN-1 software.
  • Many commercial Unix flavors have roots in BSD Unix, including: BSDI's BSD/OS, Sun Microsystems' SunOS, QNX, NextSTEP, IBM's AIX, Tru-64 Unix (formerly Digital UNIX), and Mac OS X.
  • In truth, BSD code is used in a multitude of places and products. TCP/IP, the communications protocol of the Internet, is a result of BSD development and innovation. IPv6, the successor to today's IPv4, and IPsec have both experienced strong development and support on BSD as well. Even many of today's modern operating systems which aren't based on BSD have implemented network stacks inspired by or in some cases derived from the BSD TCP/IP stack.

The most prevelent user base of BSD systems today is found on the freely available Open Source BSD flavors and their derivative projects. Besides the main BSD projects of FreeBSD, OpenBSD, and NetBSD, you can find DragonFlyBSD, PC-BSD, DesktopBSD, Freesbie, m0n0wall, pfSense, MicroBSD, PicoBSD, ClosedBSD, Frenzy, and several more.

So who actually uses *BSD? Many high-profile, high-traffic sites and companies are BSD users:

BSD's contributions to the world at large

From BSD (UC Berkeley):

  • vi
  • Sendmail
  • BIND
  • NFS
  • csh
  • 1st IP stack for Unix

From OpenBSD:

  • OpenSSH
  • OpenNTPD
  • OpenBGPD

From FreeBSD:

  • FS snapshots / background fsck
  • ...

From NetBSD:

  • ...