BIM - Berkeley in Munich
presents:

BSD
BERKELEY SOFTWARE DISTRIBUTION

fill

=0.8

fill

In this leaflet we try to give you an overview of the three open source representatives of the family of BSD UNIXoperating systems:

FreeBSD		http://www.freebsd.org/
NetBSD		http://www.netbsd.org/
OpenBSD		http://www.openbsd.org/

fill

Deutsch Uebersetzung auch erhaltlich: http://www.berklix.org/bim/leaflet/ fill

to BIM, http://www.berklix.org/bim/Jan/2003. All info unguaranteed. to Format: L^ATEX2_e on FreeBSD 4.7 Print: dvips/ps2pdf to Prepared/ Printed in Germany    -    Imprimé en Allemagne

Introduction

BSD-Unix - what's that ? That's the question that crops up often when the name shows up. This leaflet aims to give the most important answers,plus starting points to get you asking more questions that go deeper than this leaflet covers.

Many BSDs - One Philosophy

Traditionaly one divides the group of UNIX operating systems in 2 groups: System V (,,SysV`` for short) and BSD. The later originated at the University of Berkeley, California. Today's BSD Systems are direct descendants from ,,4.4BSD Lite2``, the last official BSD version from Berkeley.

The origins of BSD reach back to the 1970s, and the history is too complex to roll out here, but one can say:

• There's over 30 years development work in BSD systems, in that the software has been continually revamped to modern requirements, but without ever throwing out the entire thing and starting completely anew. As a result today BSD derivatives are mature stable Unixes without teething troubles.

• Over time, multiple loosely coupled branches of BSD have evolved, each following their own objectives, but they remain very similar and through cross porting of interfaces, drivers and applications remain interchangeable.

• Today, derivatives include: FreeBSD, NetBSD, OpenBSD, and BSDi; The later is a commercial variant. Other commercial derivatives are Mac OS-X from Apple and the completely open derivative ,,Darwin``.BSDi, Darwin and MacOS aren't dealt with more here, for lack of space.

• None of the BSDs is a ,,Linux Distribution`` - Linux and the BSDs are similar insofar as they use much of the same software, EG gcc etc.) but kernel, licence, and development models are markedly different.

Similarities

All BSDs have the following attributes and conditions in common.

BSD Licence

The majority of the source code of the BSD operating systems is available under the standard BSD licence. In contrast to the GPL licence used by the Linux Kernel, BSD licences (there are several variants) allow distribution of binaries without accompanying sources, which is important for commercial products, which are based on BSD code but for which companies want to release either no, or only partial sources.

From One Mold

Each BSD encompasses not just the kernel, but also a number of system libraries (libc, libpam...), user programs (ls, more, find, sort, lpr...) and system administrator commands (ifconfig, chown, cron, dump, restore...) as well as build tools (gcc, make, ld) as the ,,operating system``, that should be regarded as a unified whole, and maintained as such. Upgrades apply to the whole operating system and not just to the kernel, (as with Linux).

The entire operating system and the kernel can be rebuilt from the sources with just a few commands. (Recently Gentoo Linux has also offered similar capability, though without the other BSD advantages.) A strict separation between operating system and supplementary products (Apache, Netscape, OpenOffice etc) prevails, implemented in seperate source hierarchies. In consequence application programs can be updated separately, which increases the longevity of installations.

Professional Development

All BSDs maintain their complete operating system source code in a CVS repository. Thus all changes can be reconstructed, reviewed and if necessary also reversed.A release engineering team controls the entire integrated product.

Tight Organisation

The BSD projects are not undisciplined heaps of code, in which many dabble, but form professional organisations similar to commercial software projects. Each has a ,,Steering Committee``, called Core , which over-views programming sub projects etc. Around the core teams there are numerous sub projects of developers - called Commiters - responsible for addition and maintenance of documentation and drivers, and all the other tasks of the projects.

Software Galore !

All BSDs can compile and run over 99% of the source code software available from EG freshmeat.net, and there are usually also pre-built packages (Gimp, KDE, teTeX etc).

ABIs (Application Binary Interfaces) allow Linux programs to run on the BSDs, even if there is only a binary package for Linux. Thus further programs can be run on BSD even if the latest version is only available for Linux, (EG Acrobat reader, Netscape7, StarOffice 6,0, Quake3 etc.). There's no noticeable speed degradation. The quality and functionality of the Linux ABIs is however not equally well developed on all BSDs - FreeBSD has the most functionality.

Stable File System

The UFS file system has been highly valued for years and offers very high performance, by use of Softupdates the integrity of the meta data is is guaranteed in event of a crash.

Ports System

Much free software is only available in source format, or has licencing restrictions on distribution in binary Package format, (the BSD equivalent of Linux RPMs). The Ports Framework covers such contingencies. It consists of a hierarchy of Makefiles and where necessary patches, which unpack generic source packages, compile and install them. The Ports System can on its own fetch and apply sources and binaries from the Internet, or from CDROM, including building and installing any dependencies.

Individual BSDs In Detail:

FreeBSD

On normal PCs (often called x86 or i386-Hardware) FreeBSD is the most frequently encountered representative of the BSD family. This is probably because it offers the broadest hardware support for this platform, and is best optimised for it. Also it tends more than the other two to ,,functional comfortable-ness`` as experienced on other desk top systems. Thus it is more attractive for newcomers, also offering the biggest collection of ported software, with nearly 8000 packages. FreeBSD no longer regards itself just as a pure server system for skilled administrators, but aims itself also at end users, particularly newcomers from Windows and Linux. FreeBSD 5.0 (released Jan 2003) now supports a variety of computer architectures: alpha (DEC's Alpha/AXP), i386 (Intel and AMD, pentiums etc), ia64 (Intel's Itanium), pc98 (Japanese PCs), sparc64 (Sun's UltraSparc. Power PC and StrongARM ports are in progress, but not available yet. FreeBSD alone of the three offers matured SMP multi processor support.

NetBSD

NetBSD is about as old as FreeBSD. Its most outstanding characteristic is the ever growing number of hardware platforms it supports - far more architectures than any other operating system. A complete list would the exceed space available in this this leaflet, and would quickly be incomplete and obsolete so refer to the NetBSD web page. In many cases the decision to go NetBSD is easy, as it's the only one available which runs on the hardware. If one has such exotic hardware, that none of the three BSD systems run on it so far, the chance is greatest with NetBSD that a port can be achieved with acceptable effort. Although not much older than FreeBSD, NetBSD happily portrays itself as the ,,big brother`` of open source BSDs. It tends more than the other two to maintain traditional BSD characteristics. This conservative behavior also has quite a positive, compensatory effect on the other BSD systems.

OpenBSD

OpenBSD split from NetBSD in 1996, and so is by far the youngest of the three. Although it inherited a lot of platform-ports from NetBSD, some of the rarer platforms have become stunted due to lack of resources.

,,OpenBSD's`` motto and primary goal is ,,Security``. Though FreeBSD and OpenBSD have also not neglected this, it's where OpenBSD shines. This doesn't mean that OpenBSD is a ,,Security Software Stew``, rather ,,Security`` in OpenBSD also means Correctness. The team around Theo de Raadt has performed a complete line by line source code audit of the operating system to weed out any bugs and detect and remove possible vulnerabilties. (Naturally FreeBSD and NetBSD also profited from this, as appropriate corrections were adopted, where appropriate). OpenBSD's support for security also means extensive support for cryptography. Prominent here is the unique support for several hardware crypto accelerator cards and the broad integration of strong cryptography in the OS. As Theo de Raadt lives in Canada, these algorithms are not encumbered with export restrictions.

fill

to UNIX is a registered trademark and The Open Group^TM is a trademark of The Open Group^TM in the USA and other countries. All other marks and names are property of their respective owners; all appropriate registered trade marks and registered trade marks are recognized as such; their use serves only identification purposes.