Comparison of BSD operating systems
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There are a number of Unix-like operating systems based on or descended from the Berkeley Software Distribution (BSD) series of Unix variants. The three most notable descendants in current use are FreeBSD, OpenBSD, and NetBSD, which are all derived from 386BSD and 4.4BSD-Lite, by various routes. Both NetBSD and FreeBSD started life in 1993, initially derived from 386BSD, but in 1994 migrating to a 4.4BSD-Lite code base. OpenBSD was forked in 1995 from NetBSD. Other notable derivatives include DragonFly BSD, which was forked from FreeBSD 4.8, and Apple Inc.'s Mac OS X, with its Darwin base including a large amount of code derived from FreeBSD.
Most of the current BSD operating systems are open source and available for download, free of charge, under the BSD License, the most notable exception being Mac OS X. They also generally use a monolithic kernel architecture, apart from Mac OS X and DragonFly BSD which feature hybrid kernels. The various open source BSD projects generally develop the kernel and userland programs and libraries together, the source code being managed using a single central source repository.
In the past, BSD was also used as a basis for several proprietary versions of UNIX, such as Sun's SunOS, Sequent's Dynix, NeXT's NeXTSTEP, DEC's Ultrix and OSF/1 AXP (now Tru64 UNIX). Of these, only the last is still currently supported in its original form. Parts of NeXT's software became the foundation for Mac OS X, among the most commercially successful BSD variants in the general market.
Aims and philosophies
- The aim of FreeBSD is to produce an operating system usable for any purpose. It is intended to run a wide variety of applications, be easy to use, contain cutting edge features, and be highly scalable on very high load network servers. FreeBSD is free and open source, and the project prefers the BSD license. However, they sometimes accept non-disclosure agreements (NDAs) and include a limited number of closed-source HAL modules for specific device drivers in their source tree, to support the hardware of companies who do not provide purely open source drivers (such as HALs to program software-defined radios so that vendors do not share their proprietary algorithms). To maintain a high level of quality and provide good support for "production quality commercial off-the-shelf (COTS) workstation, server, and high-end embedded systems", FreeBSD focuses on a narrow set of architectures. A significant focus of development over the last five years has been fine-grained locking and SMP scalability. Other recent work includes Common Criteria security functionality, such as mandatory access control and security event audit support.
- OpenBSD aims at security, correctness, and being as free as possible. Security policies include revealing security flaws publicly, known as full disclosure; thoroughly auditing code for bugs and security issues; various security features, including the W^X page protection technology and heavy use of randomization; a "secure by default" philosophy including disabling all non-essential services and having sane initial settings; and integrated cryptography, originally made easier due to relaxed Canadian export laws relative to the United States. Concerning software freedom, OpenBSD prefers the BSD or ISC license, with the GPL acceptable only for existing software which is impractical to replace, such as the GNU Compiler Collection. NDAs are never considered acceptable. This has led to the founding of a number of child projects such as OpenSSH, OpenNTPD, OpenCVS, OpenBGPD, PF and CARP to replace restricted alternatives, and campaigns to persuade hardware vendors to release documentation. In common with its parent, NetBSD, OpenBSD strives to run on a wide variety of hardware.
- NetBSD is designed to provide a freely redistributable operating system that professionals, hobbyists, and researchers can use in any manner they wish. The main focus is portability, through the use of clear distinctions between machine-dependent and machine-independent code. It runs on a wide variety of 32-bit and 64-bit processor architectures and hardware platforms, and is intended to interoperate well with other operating systems. NetBSD places emphasis on correct design, well-written code, stability, and efficiency. Where practical, close compliance with open API and protocol standards is also aimed for. In June, 2008, the NetBSD Foundation moved to a two clause BSD license, citing changes at UCB and industry applicability.
- DragonFly BSD
- DragonFly BSD is designed to be inherently easy to understand and develop for multi-processor capable infrastructures. Starting with FreeBSD 4.8, the main aim is to radically change the kernel architecture, introducing microkernel-like message passing which will enhance scalability and reliability on symmetric multiprocessing platforms, and also be applicable to NUMA and clustered systems. The long-term goal is to provide transparent single-system image clustering. DragonFly BSD currently supports both the IA-32 platform and the x86_64 (or AMD64) platform. Matthew Dillon, the founder of DragonFly BSD, believes supporting fewer platforms makes it easier for a project to do a proper ground-up SMP implementation.
In September 2005, the BSD Certification Group, after advertising on a number of mailing lists, surveyed 4,330 BSD users, 3,958 of whom took the survey in English, to assess the relative popularity of the various BSD operating systems. About 77% of respondents used FreeBSD, 33% used OpenBSD, 16% used NetBSD, 2.6% used Dragonfly, and 6.6% used other (potentially non-BSD) systems. Other languages offered were Brazilian and European Portuguese, German, Italian, and Polish. Note that there was no control group or pre-screening of the survey takers. Those who checked "Other" were asked to specify that operating system.
Because survey takers were permitted to select more than one answer, the percentages shown in the graph, which are out of the number survey of participants, add up to greater than 100%. If a survey taker filled in more than one choice for "other", this is still only counted as one vote for other on this chart.
Another attempt to profile worldwide BSD usage is the *BSDstats Project, whose primary goal is to demonstrate to hardware vendors the penetration of BSD and viability of hardware drivers for the operating system. The project collects data monthly from any BSD system administrators willing to participate, and currently records the BSD market share of FreeBSD, OpenBSD, NetBSD, DragonflyBSD, Debian GNU/kFreeBSD, PC-BSD, and MirBSD.
The DistroWatch website, well-known in the Linux community and often used as a rough guide to free operating system popularity, publishes page hits for each of the Linux distributions and other operating systems it covers. As of December 2009, using a data span of the last six months it placed FreeBSD in 12th place with 614 hits per day; PC-BSD in 24th place with 312 hits per day; OpenBSD in 53rd place with 154 hits per day; DragonFly in 62nd place with 135 hits per day; and NetBSD in 96th place with 87 hits per day.
Names, logos, and slogans
The first BSD mascot was the BSD daemon, named after a common type of Unix software program, a daemon. FreeBSD still uses the image, a red cartoon daemon named Beastie, wielding a pitchfork, as its mascot today. In 2005, after a competition, a stylized version of Beastie's head designed and drawn by Anton Gural was chosen as the FreeBSD logo.
The NetBSD flag, designed in 2004 by Grant Bisset, is inspired by the original NetBSD logo, designed in 1994 by Shawn Mueller, portraying a number of BSD daemons raising a flag on top of a mound of computer equipment. This was based on a World War II photograph, Raising the Flag on Iwo Jima. The Board of Directors of The NetBSD Foundation believed this was too complicated, too hard to reproduce and had negative cultural ramifications and was thus not a suitable image for NetBSD in the corporate world. The new, simpler flag design replaced this. The NetBSD slogan is "Of course it runs NetBSD", referring to the operating system's portability.Puffy. Although Puffy is usually referred to as a pufferfish, the spikes on the cartoon images give him a closer likeness to the porcupinefish. The logo is a reference to the fish's defensive capabilities and to the Blowfish cryptography algorithm used in OpenBSD. OpenBSD also has a number of slogans including "Secure by default", which was used in the first OpenBSD song, 'E-railed', and "Free, Functional & Secure" and has released an original song with every release since 3.0.
The DragonFly BSD logo, designed by Joe Angrisano, is a dragonfly named Fred. A number of unofficial logos by various authors also show the dragonfly or stylized versions of it. DragonFly BSD considers itself to be "the logical continuation of the FreeBSD 4.x series." FireflyBSD has a similar logo, a firefly, showing its close relationship to DragonFly BSD. In fact, the FireflyBSD website states that proceeds from sales will go to the development of DragonFly BSD, suggesting that the two may in fact be very closely related.
PicoBSD's slogan is "For the little BSD in all of us," and its logo includes a version of FreeBSD's Beastie as a child, showing its close connection to FreeBSD, and the minimal amount of code needed to run as a Live CD.
A number of BSD OSes use stylized version of their respective names for logos. This includes Mac OS X (which only uses the X), PC-BSD, DesktopBSD (with a symbol on the side), ClosedBSD (curved into a semicircle), Frenzy (with symbol on the side), and MicroBSD (which includes a bull-like M with yellow eyes). The Mac OS X logo is the Roman numeral for 10. This is intended to emphasize the change from previous versions of Mac OS, which were not based on BSD and had version numbers expressed using Arabic numerals. PC-BSD's slogan is "Personal computing, served up BSD style!", DesktopBSD's "A Step Towards BSD on the Desktop." MicroBSD's slogan is "The small secure unix like OS."
MirOS's site collects a variety of BSD mascots and Tux, the Linux mascot, together, illustrating the project's aim of supporting both BSD and Linux kernels. MirOS's slogan is "a wonderful operating system for a world of peace."
|Primary developers||First public release||Based on||Latest stable version||Cost (USD)||Preferred license||Purpose||Short description|
|FreeBSD||The FreeBSD Project||Dec 1993||386BSD, 4.4BSD-Lite||8.0||25 November 2009||Free||BSD||Server, Workstation, Network Appliance, Embedded||Aims for maximum performance.|
|OpenBSD||The OpenBSD Project||July 1996||NetBSD||4.6||18 Oct 2009||Free||ISC||Server, Workstation, Network Appliance, Embedded||Aims for maximum security.|
|NetBSD||The NetBSD Project||May 1993||386BSD, 4.4BSD-Lite||5.0.1||2 Aug 2009||Free||BSD||Server, Workstation, Network Appliance, Embedded||Aims for maximum portability.|
|DragonFly BSD||Matt Dillon||12 Jul 2004||FreeBSD 4.8||2.4.1||O1 Oct 2009||Free||BSD||Server, Workstation, Network Appliance, Embedded||Emphasis on multiprocessor systems, and clustering|
|386BSD Template:Fn||William and Lynne Jolitz||Mar 1992||4.3BSD Net/2||1.0||1994||Free||BSD||Historical|
|BSD/OS (BSD/386) Template:Fn||BSDi, Wind River Systems||Mar 1993||4.3BSD Net/2, 4.4BSD||5.1||Oct 2003||Proprietary||Historical|
|SunOS Template:Fn||Sun Microsystems||1982||4.xBSD, UNIX System V||4.1.4||Nov 1994Template:Fn||Proprietary||Historical (Solaris is a different code base)|
|Ultrix Template:Fn||Digital Equipment Corporation||1984||4.2BSD, SVR2||4.5||1995||Proprietary||Historical|
|Tru64 UNIX (OSF/1 AXP, Digital UNIX)||DEC, Compaq, HP||1993||4.3BSD, 4.4BSD, Mach 2.5, UNIX System V||5.1B-4||Dec 2006||Non-free$99 (non-|
|Mac OS X||Apple Inc.||Mar 2001||Darwin||10.6 "Snow Leopard"||28 August 2009||Non-freeDesktop $29 when upgrading from 10.5|
$169 (including iLife 09 and iWork 09) when upgrading from earlier versions
Server $499 (unlimited clients)
|Open source core system (APSL, GPL, others) with proprietary higher level API layers||Workstation, Home Desktop, Server||Ships with Apple hardware and is locked to it.|
|Darwin||Apple Inc.||Mar 2001||NeXTSTEP, FreeBSD, Mac OS||9.2||11 February 2008||Free||APSL, GPL, others||Workstation, Home Desktop, Server||The kernel and certain userland components of OS X|
|PC-BSD||Kris Moore, Mike Albert, Tim McCormick, Dimitri Tishchenko||29 Apr 2006||FreeBSD||7.1.1 "Galileo"||06 Jul 2009||Free||BSD||Desktop||Easy to use while maintaining full use of FreeBSD base|
|DesktopBSD||Peter Hofer, Daniel Seuffert||25 Jul 2005||FreeBSD||1.7||07 Sept 2009||Free||BSD||Desktop||Easy to use|
|ClosedBSD||Joshua Bergeron and various contributors||FreeBSD||1.0B (floppy), 1.0-RC1 (CD)||Free||Proprietary||firewall/NAT, boot floppy, Live CD|
|FreeSBIE||FreeBSD||2.0.1||Feb 2007||Free||Live CD of FreeBSD|
|Frenzy||Mozhaisky Sergei||FreeBSD||1.1||08 Dec 2008||Free||"portable system administrator toolkit"||Live CD|
|PicoBSD||Michael Bialecki||FreeBSD||0.42||Free||BSD||boot floppy|
|polyBSD||FOSS Tools Team||NetBSD||3.1||Free||BSD||live USB||development platform for embedded systems|
|Anonym.OS||beta as of Jan 2005||OpenBSD 3.8||none||Free||Anonymous browsing||Live CD|
|MirOS BSD||The MirOS Project||OpenBSD 3.1||#10||16 Mar 2008||Free||European|
|ekkoBSD Template:Fn||Rick Collette||OpenBSD 3.3||Server||easy to administer|
|MicroBSD Template:Fn||Bulgarians||OpenBSD 3.0/3.4||0.6||27 Oct 2003||Free||General purpose||Small, secure|
|OliveBSD||Gabriel Paderni||OpenBSD 3.8||Free||Live CD|
|Gentoo/FreeBSD||Gentoo Linux developers||FreeBSD||Free||GPL, BSD||Server, Workstation, Network Appliance||uses Gentoo framework|
|Gentoo OpenBSD||Gentoo Linux developers||OpenBSD||Free||GPL, BSD||Server, Workstation, Network Appliance, Embedded||uses Gentoo framework|
|Gentoo NetBSD||Gentoo Linux developers||NetBSD||Free||GPL, BSD||Server, Workstation, Network Appliance, Embedded||uses Gentoo framework|
|Gentoo DragonflyBSD||Robert Sebastian Gerus (project not yet officially supported by Gentoo)||DragonFly BSD||Free||Server, Workstation, Network Appliance||uses Gentoo framework|
|Debian GNU/kFreeBSD||GNU, FreeBSD||Free||GNU userspace on FreeBSD kernel|
|Debian GNU/NetBSD||GNU, NetBSD||Free||GNU userspace on NetBSD kernel|
|MidnightBSD||Lucas Holt||FreeBSD 6.0||none||none||Free||BSD||Desktop||GNUstep based Desktop Environment|
|pfSense||various contributors||1.0||FreeBSD||1.2||25 Feb 2008||Free||BSD||Security appliance||firewall/NAT, Live CD|
|Paxym-FreeBSD for Octeon/Mips||Paxym Inc. OS/Kernels team||4.0 - 11-Dec-2007||FreeBSD 7.0||4.7||13 Aug 2008||Proprietary||Network, Storage, Security Applications: Routers/UTM/Firewall/NAS||For Mips32, Mips64, SMP Mips64 Octeon Cavium Networks 1-16 Multicore CPU |
|Developer||First public release||Based on||Version||Release Date||Cost (USD)||Preferred license||Purpose||Short description|
Template:Fnb 386BSD, BSD/OS, SunOS, and Ultrix are historic operating systems that are no longer developed. BSDeviant and ekkoBSD do not exist anymore either, although BSDeviant is still available for download (see external links). MicroBSD ended, then started again in 2003, but it does not seem that any progress has been made since then, though the website still exists.
Template:FnbThis article only refers to SunOS through version 4.x. SunOS from release 5.x forward is based on SVR4, and is most commonly referred to as the Solaris Operating System.
|Supported architectures||Supported file systemsTemplate:Fn||Kernel type||GUI on by defaultTemplate:Fn||Package management||Update management||Primary APIsTemplate:Fn|
|FreeBSD||x86, x86-64, PC98, Itanium, UltraSPARC, ARM, MIPS, PPC, others||UFS, UFS2, ext2, FAT, ISO 9660, UDF, NFS, SMBFS, NetWare (nwfs), NTFS (limited read-write), ReiserFS (read only), XFS (experimental), ZFS, FUSE, Coda (experimental), AFS, others||Monolithic with modules||No (X.Org available)||ports tree, packages||source (CVSup, portsnap), network binary update (freebsdupdate)||BSD, POSIX|
|OpenBSD||x86, 68k, Alpha, x86-64, SPARC, VAX, others||UFS, UFS2, ext2, FAT, ISO 9660, UDF, NFS, NTFSTemplate:Fn (read only), AFS, others||MonolithicTemplate:Fn||No (X.Org included)Template:Fn||ports tree, packages||source (CVS, CVSup, rsync) or binary upgrade||BSD, POSIX|
|NetBSD||x86, 68k, Alpha, x86-64, PPC, SPARC, UltraSPARC, PowerPC, ARM, others||UFS, UFS2, ext2, FAT, ISO 9660, NFS, LFS, UDF, SMBFS, Coda, HFS+ (read only), EFS (read only), NTFS (read only), TMPFS, FUSE, PUFFS (BSD replacement of FUSE), ADOS (AmigaDOS file system), filecorefs (Acorn RISC OS file system), others||Monolithic with modules||No (X.Org or XFree86 included)Template:Fn||pkgsrc, packages||source (CVS, CVSup, rsync) or binary (using sysinst)||BSD, POSIX|
|Ultrix||VAX, PDP-11, MIPS||UFS + others||Monolithic||No (X11 included)||setld||unknown||BSD, POSIX (4.0 onwards)|
|Tru64 UNIX||Alpha||UFS, AdvFS, ISO 9660, UDF, NFS||Hybrid||Yes (CDE)||setld||dupatch||POSIX, UNIX 98, X11, CDE, others|
|Mac OS X / Darwin||PPC, x86, x86-64, ARM||HFS+ (default), HFS, UFS, AFP, ISO 9660, FAT, UDF, NFS, SMBFS, NTFS (read only), FTP, WebDAV, others||Hybrid||Yes (Aqua)||OS X Installer||Software Update||Carbon, Cocoa, BSD/POSIX, CF, X11 (since 10.3)|
|DragonFly BSD||x86, x86-64||HAMMER, UFS, FAT, ISO 9660, NFS, SMBFS, NTFS (read only), ext2, others||Hybrid||No (X.Org available)||pkgsrc, packages||Git||BSD, POSIX|
|PC-BSD||x86, x86-64||UFS, UFS2, FAT, ISO 9660, NFS, SMBFS, NTFS (read only), others||Monolithic with modules||Yes (KDE)||graphical installation wizard, ports tree||CVSup, Portsnap, network binary update (Online Update)||BSD, POSIX, X11, KDE|
|MidnightBSD||x86, x86-64||UFS, UFS2, ext2, FAT, ISO 9660, UDF, NFS, SMBFS, NetWare (nwfs), NTFS (read only), others||Monolithic with modules||No (X.Org available)||ports tree, packages||source CVSup||BSD, POSIX, X11, GNUstep|
Template:Fnb UFS and UFS2 are descendants of the old FFS. However, many BSD operating systems refer to UFS1 as FFS.
Template:Fnb Operating systems where the GUI is not installed and turned on by default are often bundled with an implementation of the X Window System. However, installing X is usually optional.
Template:Fnb Most operating systems use proprietary APIs in addition to any supported standards.
Template:Fnb OpenBSD's NTFS support is not enabled by default and requires a custom kernel.
Template:Fnb OpenBSD contains support for modules on some architectures. They are used only to add third-party features: extracting existing functions into modules in the same manner as FreeBSD is not possible.
Template:Fnb Unlike FreeBSD, OpenBSD includes the X Window System as base install sets rather than packages within the ports collection. It includes some local changes and is managed as part of the OpenBSD source tree.
Template:Fnb NetBSD includes either X.Org or XFree86 (depending on platform) as a base install set and includes some local changes, maintained within the NetBSD source tree.
|Resource access control||Security logging||Subsystem isolation mechanisms||Integrated firewall||Encrypted file systems||Data execution prevention|
|FreeBSD||Unix, ACLs, MAC||syslog, CAPP event auditing, OpenBSM||chroot, jail, MAC partitions||IPFW2, IPFilter, PF||Yes||Yes||No|
|OpenBSD||Unix||syslog||chroot, systrace, privilege separation||PF||YesTemplate:Fn||Yes||Yes|
|NetBSD||Unix, Veriexec||syslog||chroot, privilege separation||IPFilter, PF||Yes||Yes||No|
|Mac OS X||Unix, ACLs||syslog, CAPP event auditing, OpenBSM||chroot, sandbox||IPFW2||Yes||Yes||unknown|
|PC-BSD||Unix, ACLs, MAC||chroot, jail, MAC Partitions||IPFW2, IPFilter, PF||YesTemplate:Fn||Yes||No|
|DragonFly BSD||Unix||syslog||chroot, jail, VKernel||IPFW2, IPFilter, PF||Yes||No||No|
|MidnightBSD||Unix, ACLs, MAC||syslog||chroot, jail, MAC partitions||IPFW2, IPFilter, PF||Yes||No||No|
Template:Fnb Swap space encrypted by default on OpenBSD 3.8 and above
Template:Fnb Additionally swap space may be encrypted during installation, uses memory based tmp file storage by default.
- List of BSD operating systems
- BSD license
- Comparison of open source operating systems
- Comparison of operating systems
Notes and references
- ↑ "Chapter 1 Introduction: 1.2. - What is the goal of the FreeBSD Project?". Frequently Asked Questions for FreeBSD 4.X, 5.X, and 6.X. The FreeBSD Documentation Project. 1995-2006. http://www.freebsd.org/doc/en_US.ISO8859-1/books/faq/introduction.html#FREEBSD-GOALS. Retrieved 2006-04-22.
- ↑ "About FreeBSD". The FreeBSD Project. 2006-10-12. http://www.freebsd.org/about.html. Retrieved 2006-10-14.
- ↑ "Support for Multiple Architectures: Statement of General Intent". Committer's Guide. The FreeBSD Documentation Project. ©1999-2005. http://www.freebsd.org/doc/en_US.ISO8859-1/articles/committers-guide/archs.html#AEN1248. Retrieved 2006-10-14. "The FreeBSD Project targets "production quality commercial off-the-shelf (COTS) workstation, server, and high-end embedded systems"."
- ↑ "OpenBSD Project Goals". OpenBSD. 2005-10-12. http://www.openbsd.org/goals.html. Retrieved 2006-04-22.
- ↑ "About the NetBSD Project - What is the NetBSD project?". The NetBSD Foundation, Inc.. 2006-01-08. http://www.netbsd.org/Misc/about.html. Retrieved 2006-04-22.
- ↑ "DragonFly Frequently Asked Questions". The DragonFly BSD Project. http://www.dragonflybsd.org/docs/FAQ.cgi. Retrieved 2006-07-01.
- ↑ Biancuzzi, Federico (2004-07-08). "Behind DragonFly BSD An Interview with the developers.". O’Reilly Media, Inc.. pp. 3. http://www.onlamp.com/pub/a/bsd/2004/07/08/dragonfly_bsd_interview.html?page=1. Retrieved 2006-04-29.
- ↑ 8.0 8.1 8.2 BSD Certification site; PDF of usage survey results. Retrieved on 2006-04-22.
- ↑ "*BSD Usage Statistics". The *BSD Stats Project. http://www.bsdstats.org. Retrieved 2006-09-30.
- ↑ "DistroWatch.com: Put the fun back into computing.". DistroWatch.com. 2001-2009. http://distrowatch.com/. Retrieved 2009-12-23.
- ↑ "Chapter 1 Introduction - Why is it called FreeBSD?". Frequently Asked Questions for FreeBSD 4.X, 5.X, and 6.X. The FreeBSD Documentation Project. 1995-2006. http://www.freebsd.org/doc/en_US.ISO8859-1/books/faq/introduction.html#WHY-CALLED-FREEBSD. Retrieved 2006-06-11.
- ↑ "About the NetBSD Project - Why the name?". The NetBSD Foundation. 1994-2006. http://www.netbsd.org/Misc/about.html#name. Retrieved 2006-12-06.
- ↑ FreeBSD Logo Competition. The FreeBSD Project. Competition ended 2005-06-30. Retrieved on 2006-04-22.
- ↑ Mueller, Shawn (1994). "Original NetBSD Logo" (JPEG). The NetBSD Foundation. http://www.netbsd.org/images/NetBSD-old.jpg. Retrieved 2006-04-22. Also see NetBSD Logos.
- ↑ Mewburn, Luke (2004-01-14). "NetBSD logo design competition". Netbsd-advocacy mailing list. http://mail-index.netbsd.org/netbsd-advocacy/2004/01/14/0001.html. Retrieved 2006-04-22.
Linked to from:
"Changes and NetBSD News in 2004 - NetBSD Logo Design Contest". The NetBSD Foundation, Inc.. 2004-01-13. http://www.netbsd.org/Changes/2004.html#logo-contest. Retrieved 2006-10-14.
"The NetBSD Foundation Press Release: Announcement of New Logo - NetBSD has a new logo!". The NetBSD Foundation, Inc.. 2004-10-30. http://www.netbsd.org/Foundation/press/new-logo.html. Retrieved 2006-04-22.
- ↑ "OpenBSD 3.9 - Free, Functional & Secure" (JPEG). OpenBSD. http://www.openbsd.org/images/puffy39.jpg. Retrieved 2006-07-01.
- ↑ "OpenBSD release song lyrics". OpenBSD. 2006-04-15. http://www.openbsd.org/lyrics.html. Retrieved 2006-04-22.
- ↑ official DragonFlyBSD artwork
- ↑ "DFWiki - DragonFly Artwork". The DragonFlyBSD Project. 2006-03-28. http://web.archive.org/web/*/http://wiki.dragonflybsd.org/index.php/DragonFly_Artwork. Retrieved 2006-04-22. (This page was noted to be a redirect to the front page of new DragonFly Wiki on 2006-06-17, but most of the old images remain available via the Wayback Machine.)
- ↑ "The History of DragonFly". The DragonFly BSD Project. http://www.dragonflybsd.org/about/history.cgi. Retrieved 2006-04-22.
- ↑ "PicoBSD Banner - For the little BSD in all of us" (GIF). The FreeBSD Project. http://web.archive.org/web/20060503041952/http://people.freebsd.org/~picobsd/images/picobsdbanner.gif. Retrieved 2006-04-22.
- ↑ "ClosedBSD logo" (JPEG). Archived from the original on 2005-03-18. http://web.archive.org/web/20050306153339/www.closedbsd.org/images/logo.jpg. Retrieved 2006-10-14. Original last retrieved on 2006-04-22.
- ↑ Vitalievich, Mozhaisky Sergei. "Frenzy logo" (PNG). http://frenzy.org.ua/frenzy-logosite.png. Retrieved 2006-04-22.
- ↑ "MicroBSD logo - The small secure unix like OS" (PNG). http://www.microbsd.net/images/logo.png. Retrieved 2006-04-22.
- ↑ "MirOS/MirPorts: a wonderful operating system for a world of peace". MirOS Project. http://mirbsd.mirsolutions.de/. Retrieved 2006-04-22.
- ↑ "SunOS 4.1.3: svidii - overview of the System V environment". FreeBSD Hypertext Man Pages. The FreeBSD Project. 1989-09-30. http://www.freebsd.org/cgi/man.cgi?query=svidii&apropos=0&sektion=0&manpath=SunOS+4.1.3&format=html. Retrieved 2006-06-14.
- Milo et al. (1998-06-22 - 2004-03-31). "FreeBSD". Operating System Technical Comparison. OSdata. http://www.osdata.com/oses/freebsd.htm. Retrieved 2006-06-02.
- Milo et al. (1998-06-22 - 2004-04-19). "OpenBSD". Operating System Technical Comparison. OSdata. http://www.osdata.com/oses/openbsd.htm. Retrieved 2006-06-02.
- Milo et al. (1998-06-22 - 2004-04-19). "NetBSD". Operating System Technical Comparison. OSdata. http://www.osdata.com/oses/netbsd.htm. Retrieved 2006-06-02.
- Milo et al. (1998-06-22 - 2002-02-17). "SunOS". Operating System Technical Comparison. OSdata. http://www.osdata.com/oses/sunos.htm. Retrieved 2006-06-02.
- "SunOS & Solaris version history". Berkeley. http://www.ocf.berkeley.edu/solaris/versions/. Retrieved 2006-06-02.
- "Ultrix FAQ". 1996-11-04. http://www.supelec.fr/decus/faq/faq-ultrix.html. Retrieved 2006-06-02.
- Milo et al. (1998-06-22 - 2002-04-10). "Ultrix". Operating System Technical Comparison. OSdata. http://www.osdata.com/oses/ultrix.htm. Retrieved 2006-06-02.
- Milo et al. (1998-06-22 - 2002-03-20). "Mac OS X". Operating System Technical Comparison. OSdata. http://www.osdata.com/oses/macosx.htm. Retrieved 2006-06-02.
- Milo et al. (1998-06-22 - 2002-03-20). "Mac OS X Server". Operating System Technical Comparison. OSdata. http://www.osdata.com/oses/mxs.htm. Retrieved 2006-06-02.
- "BSDeviant download page". Bsdeviant.org. http://bsdeviant.org/. Retrieved 2008-06-30. A semi-official download page.
- "ekkoBSD 1.0 BETA1B Released". Slashdot. 2003-11-25. http://bsd.slashdot.org/article.pl?sid=03/11/25/2331244. Retrieved 2006-06-03.
- Milo et al. (1998-05-31 - 2006-02-01). "Operating System Technical Comparison". OSdata. http://www.osdata.com/. Retrieved 2006-06-02.
- Brown, Martin (2004-08-10). "Differentiating Among BSD Distros". Jupitermedia Corporation. pp. 4. http://www.serverwatch.com/tutorials/article.php/3393051. Retrieved 2006-06-03.
- Schneider, Wolfram; Gilliam, Josh and Schultz, Steven M. (1997-2004). "The UNIX system family tree: Research and BSD" (ASCII). The NetBSD Foundation. ftp://ftp.netbsd.org/pub/NetBSD/NetBSD-current/src/share/misc/bsd-family-tree. Retrieved 2006-06-03.