OpenBSD

OpenBSD branched off from NetBSD in 1996 with the goal of becoming the most secure BSD. OpenBSD was the first to support hardware−accelerated cryptography (allowing it to encrypt and decrypt information at a remarkable rate), and the developers are rather proud of the fact that their default install hasn't been hacked remotely for over four years.

The OpenBSD people have audited the entire BSD code base, fixing most (but not all) potential security holes before they can be exploited. OpenBSD is not as friendly or as easy to use as FreeBSD, however.

BSD/OS

BSD/OS, produced by Wind River Systems, is a commercial, closed−source operating system that greatly resembles FreeBSD. Some hardware manufacturers will not release hardware specifications without nondisclosure agreements, and developers for a freely available operating system cannot develop device drivers for such proprietary hardware. BSD/OS supports much of this hardware.

A great deal of the BSD/OS code is available to FreeBSD committers, and FreeBSD absorbs BSD/OS enhancements that don't break nondisclosure agreements.

Mac OS X

Mac OS X? That's right. Large chunks of FreeBSD were incorporated into Apple's Mac OS X. If you're looking for a stable operating system with a friendly face and a powerful core, Mac OS X is unquestionably for you. While FreeBSD makes an excellent desktop for a computer professional, I wouldn't put it in front of grandma. I would put Mac OS X in front of grandma without a second thought, and even feel that I was doing the right thing.

Mac OS X includes a lot of things that aren't at all necessary for an Internet server, however, and it only runs on Apple hardware, so I don't recommend it for an inexpensive, high−powered server.

While you cannot get the user interface source code for Mac OS X, you can view the operating system's BSD core and Mach kernel; Apple has released them under the code name Darwin.

Other UNIXes

There are several other UNIX operating systems out there, some of which have even rented the trademark UNIX so they can label themselves as such. This list is by no means exhaustive, but we'll touch the high points.

Solaris

The best−known UNIX is Sun Microsystems' Solaris. Solaris runs on high−end hardware that supports dozens of processors and gobs of disks. (Yes, "gobs" is a technical term.) It's used by many enterprise−level applications, such as Oracle.

Solaris runs mainly on the SPARC hardware platform, which is manufactured by Sun. Since Sun controls both the hardware and software, they can make their systems support many interesting features, such as hot−swappable memory and main boards.

9