When you think of the PowerPC processor, chances are you’ll think of just two platforms and, by association, two operating systems. Apple’s Mac OS X, which runs on Apple’s own hardware, and the AIX Unix operating system from IBM, which runs on their own PowerPC platform systems. In reality, there is a wide choice of potential operating systems that work on a wide range of PowerPC platforms. If you want a Unix-like alternative to AIX, particularly a free software one, then Linux seems the obvious choice, but there are others. BSD provides a Unix operating system, but with a heritage that goes back a lot further than Linux. If you chose to go down the BSD route, what solutions are available for the PowerPC platform? And, are they as good as Linux and proprietary alternatives?

The BSD operating system

All Unix flavors are typically based on the original version of Unix developed by AT&T. The BSD variant of Unix available now is a free software version of the AT&T Unix developed at the University of California, Berkeley. Proprietary and free software flavors of Unix available today, can all trace their heritage back to one of these two basic versions of the Unix operating system. Over the years different companies have based their Unix offering on either the AT&T (commonly referred to as AT&T System V Release 4 (SVR4)) or the BSD version.

There have also been a few changes over the years. For example, versions of Sun’s SunOS operating system, up until SunOS 4.1.x, were based on the BSD code base, but then switched to an SVR4 base with SunOS 5.x, better known as Solaris. These changes are akin to a car manufacturer choosing a different engine manufacturer for the car—there are changes to certain parts of the internal workings, but the basics of internal combustion stay the same, and the outer shell to remains relatively unchanged.

Today, the most popular implementations of BSD are the free software ones, much the same as Linux. But BSD has that much older heritage and over the years certain aspects of the inner workings of BSD have been improved and expanded upon, particularly with respect to networking and security, generally making BSD more stable and giving it a higher performance for certain operations. BSD has for many years had one of the best network stacks available often exceeding the nearest competitor on network throughput, utilization and connection initiations. Hackers and crackers are frequently challenged to break into BSD based systems and have no success.

This heritage in networking has meant that BSD is regularly used in routers and network servers and as a platform for web services. Unfortunately, it has failed to capture the same hype and following as Linux. Though, it does have its dedicated followers, including myself, for use as a general purpose Unix platform.

The FreeBSD website

BSD variants

There are quite a few variants of the BSD operating system, all of which share a common foundation within the original Berkeley Systems Distribution edition of the operating system. The differences that exist are in the focus of the development, including performance, target platforms, flexibility and security.

There are four mainstream versions of BSD that most people are familiar with:

• FreeBSD—Focused on performance, FreeBSD is the most popular of the BSD solutions after being released by Walnut Creek CD-ROM, an early pioneer of freeware and shareware distributions before the internet became mainstream. FreeBSD has the largest user base, probably because of the size of the development team and the number of applications that have also been ported to the operating system. FreeBSD is not, at the time of writing, fully available on the PowerPC platform, although there is an active porting project in progress.
• NetBSD—Focused on portability, NetBSD is best known for it’s wide-ranging hardware support. You can run NetBSD on everything from an embedded solution to proprietary hardware from IBM, Sun and others. If you need to support a Unix platform on different PowerPC based platforms including VME, evaluation boards, IBM pSeries and RS/6000 hardware, PowerPC based Macs and even old BeBoxes, then NetBSD is the solution for you. Beyond the hardware environment, NetBSD also has the same strong networking foundation of other BSD variants along with similar security and stability.
• OpenBSD—Focused on security, OpenBSD is technically a fork of the NetBSD code. Contrary to the name, OpenBSD is, upon initial installation, closed. All of the main network services are disabled until you enable them and much of the operating system is in a “switched off” state until the administrator says otherwise. This means that OpenBSD is, out of the box, incredibly secure; to use a network service, for example SSH, you’ll need to specifically set up SSH, open the ports and configure the keys and background daemon, before using it to administer your system. Although this seems long-winded, it really does mean that as an administrator, you must explicitly allow potential security problems, rather than the implicit approach used on other operating systems. OpenBSD also includes extensive encryption and security options making it incredibly popular with network administrators for use in routers and web servers. OpenBSD is available for Apple’s Mac-based PowerPC hardware, but not any other PowerPC platforms.

The OpenBSD website

• Darwin—Darwin is produced by Apple and is available for free, although it’s not heavily publicized. Darwin is based on FreeBSD (changes in Darwin are actually added back into the FreeBSD code base), but with additions and added functionality for use on, and more importantly with, Apple systems. For example, Darwin incorporates functionality for integration with the Apple LDAP-based authentication system, and the necessary base libraries and components to enable you to use Darwin for QuickTime streaming. The server software is available on the Darwin homepage. The Darwin OS also forms the basis of Apple’s proprietary Mac OS X operating system, when combined with the Cocoa user interface and other components, such as QuickTime. The benefit, from a user (and administrators) point of view, is that you get a rich GUI environment for applications like Microsoft Word and Adobe Photoshop, but with the underpinnings of a Mach kernel and BSD operating system that provide stability and security and make it easy to support applications like Apache and MySQL.

Aside from Darwin, the other three are licensed using Berkeley’s free BSD License that allows complete access to, and use of, the code for any purpose. Darwin is licensed under the Apple Public Source License, which is a little more restrictive to help protect the work carried out by Apple on what is the underpinning of a proprietary product.