3.1 About the operating systems
A general overview of the operating systems that are covered in this guide
has been provided here. Readers must note: These are my personal views and have
nothing to do with the views of the Linux or FreeBSD or OpenBSD or in general
terms, the Open-Source community.
3.1.1 Microsoft Windows: Microsoft Corp. has a long (yet fatally
weak and buggy) list of operating systems, targets ranging from the mild
and feeble home-user to the truly multi-tasking, multi-processing,
multi-programming, fault-tolerant, hack-resilient real-time systems; from MS
Windows 95 to the powerful Microsoft Windows 2000 Advanced Server. The
reader is free to choose any OS according to his/her own personal taste and/or targeted environment. I personally do
"not" consider Microsoft Windows 2000 family of OSes (which includes Windows 2000 Professional, Windows 2000 Server, Windows 2000 Advanced Server and Windows 2000 Datacenter server) a very good choice for "corporate" environments. If the PASSME theme of Software engineering is
considered, where PASSME = Performance, Availability, Stability, Security, Maintainability and Extensibility features of any software under scrutiny; Microsoft Windows 2000 servers
(and operating systems, in general) are rated much lower than UNIX SVR4, *BSDs, Sun Solaris, Linux and any of the other commercial variants of UNIX like IBM-AIX, HP-UX
and so on.
Anyway, I personally believe, "freedom of choice of OS is a birthright for all". So,
it is the reader's choice, whether he/she uses Windows 98 or Windows 2000 Professional. Personally, I like tinkering with Microsoft Windows XP, which is the next version of Microsoft
Windows beyond Windows 2000 and Windows Millennium. Windows XP brings the convergence of Windows operating systems by integrating the strengths of Windows 2000 - standards-based security, manageability and reliability with the best features of Windows 98 and Windows Me, Plug and Play, easy-to-use user interface, and innovative support services to create the
best Windows yet. Windows XP is NOT a "free" operating system as like Linux, FreeBSD, NetBSD, OpenBSD and other such open-source software
projects.
- For Microsoft Windows XP Professional "Overview", visit
http://www.microsoft.com/catalog/display.asp?site=10798&subid=22&pg=1
- For "System requirements", visit
http://www.microsoft.com/catalog/display.asp?site=10798&subid=22&pg=3
- Visit Microsoft Windows XP Professional homepage at
http://www.microsoft.com/windowsxp/pro/default.asp
3.1.2 Linux: Linux is the kernel or core of an operating system
called GNU/Linux system, where the GNU Project provides the software and
applications that runs on the Linux kernel. The Linux kernel, originally written
by Linus Benedict Torvalds, is a UNIX-clone, which is POSIX compliant and was
initially targeted towards the Intel x86 architecture. As rightly mentioned in the "Linux Information Sheet" by Michael K. Johnson
at http://www.tldp.org, "...Linux is a completely free reimplementation of the POSIX specification, with SYSV and BSD extensions (which means it looks like
Unix, but does not come from the same source code base), which is available in both source code and binary form. Its copyright is owned by Linus Torvalds ; and other contributors, and is freely redistributable under the terms of the GNU General Public License (GPL). A copy of the GPL is included with the Linux source; you can also get a copy from ftp://prep.ai.mit.edu/pub/gnu/COPYING...". Readers
must note the fact that though many Linux users worldwide refer to the GNU/Linux
operating system simply as "Linux", it is more appropriate to refer to
the operating system as a GNU/Linux system and when talking about the Kernel in
particular just to call it Linux. Moreover, a very popular misconception amongst
new Linux users is: "Hey! Linux is UNIX!". No, absolutely
"not". Once
again, readers must note: The Linux kernel is a UNIX-clone, in other words a
reimplementation of the UNIX-Kernel, but it is not UNIX itself. On the other hand, the
BSDs, FreeBSD and OpenBSD for example, are not kernels merely. They are more
closer to the real UNIX (AT&Ts Official Release UNIX SVR4). They represent
an entire operating system with a whole set of applications, tools, user
utilities, shells, games, documentation, developer utilities, system and
user-level binaries and full source code for the operating systems.
3.1.3
FreeBSD:
FreeBSD which stands for the Free version of Berkeley Software Distribution
operating system software (though all the BSDs out there are
"open-source" or "free" in nature) is technically speaking,
the most powerful, professional quality and advanced UNIX-compatible operating
system software on earth today. FreeBSD is originally based on 4.4BSD-Lite (with
a minor inclusion from the 4.4BSD-Lite2 code base too), developed at the
University of California, Berkeley, under the authorization of the Computer
Systems Research Group (CSRG), Computer Science Division, Department of Electrical Engineering and
Computer Science at Berkeley. FreeBSD operating system (just like a Linux
distribution) comes with a whole set of packages, including user applications,
tools, user utilities, shells, games, documentation, developer utilities, system
and user-level binaries and full source code for the operating systems. The
FreeBSD Project web-site can be accessed at: http://www.freebsd.org.
Recently, a lot of media spotlight has put the GNU/Linux system (more
specifically the Linux Kernel) in a stardom status. Some rate Linux as the best
ever written UNIX-clone that would spell disaster for UNIX and other UNIX-clones
and UNIX-compatibles out there in the market. But in reality it is not so.
Readers must note: Just as the power of an automobile comes from the quality of
the engine running under it's hood, similarly features like stability,
reliability, extensibility and robustness of an operating system software comes
from the internal structure of the Kernel or the core of that corresponding
operating system. I personally feel that both the Linux and the FreeBSD Kernel
are great works of creativity and tremendous effort and just a user-level or
technical comparison between the 2 is meaningless. Situations where memory is a
scarcity and moreover gets crunched and stressed upon real hard, the Linux
Kernel breaks down. FreeBSD with it's highly optimized and advanced VM/Swap
system comes to the rescue! On the other hand, under given situations, Linux may
outperform FreeBSD by a mile. The significant point for readers to note and
remember is that the Linux Kernel favors simplicity over highly optimized and
dynamic yet more complex code whereas the FreeBSD Kernel optimizes performance
by introducing more complex code and heavily optimizing the code base by
rearranging and rewriting some of the more important internal algorithms and
data structures from time to time.
A complete and exhaustive discussion on Linux and FreeBSD Kernels is beyond
the scope of this guide. If readers find it interesting, they may search the
Internet for more Linux and/or FreeBSD specific information. I would suggest the
readers to read "Understanding the Linux Kernel" by Bovet and Cesati
for getting more in-depth information on the inner-workings of the Linux
Kernel, "The Design and Implementation of the 4.4BSD Operating System"
for FreeBSD/OpenBSD and so on, and "The Design of the
UNIX Operating System" by M. Bach for UNIX SVR4 internals.
3.1.4 OpenBSD: The BSD family, other than the dominant big-brother
FreeBSD, also consists of OpenBSD, NetBSD, BSD/OS and Darwin operating systems.
OpenBSD is a fully functional, multi-platform UNIX-like Operating System based
on Berkeley Networking Release 2 (Net/2) and 4.4BSD-Lite. The OpenBSD team
strives to achieve what is called "a secure by default" status. This means that
an OpenBSD user should feel safe that their newly installed machine will not be
compromised. This "secure by default" goal is achieved by taking a proactive
stance on security. FreeBSD -RELEASES target stability and reliability under the most adverse of
conditions whereas OpenBSD -RELEASES target optimum security in corporate
environments. The OpenBSD operating system software has been labeled "the
proactively secure Unix-like operating system". The OpenBSD
Kernel is heavily optimized with security features thereby providing customers
with utmost secure and hack-resilient real-time systems. The OpenBSD Project web-site can be accessed at:
http://www.openbsd.org.
The OpenBSD operating system software has integrated strong cryptography into
the base system. A fully functional IPsec (Internet Protocol Security)
implementation is provided as well as support for common protocols such as SSL
(Secure Sockets Layer) and SSH (Secure Shell). Network filtering and monitoring
tools such as packet filtering, NAT (Network Address Translation), and bridging
are also included. For high performance demands, support for hardware
cryptography has also been added to the base system. OpenBSD provides as many
security options as possible to allow the user to enjoy secure computing without
feeling burdened by it.
- For browsing through the Official FreeBSD Handbook, visit:
http://www.freebsd.org
- The official sources for FreeBSD are available via anonymous FTP from:
ftp://ftp.FreeBSD.org/pub/FreeBSD/
- For a comparative study between FreeBSD, Linux and Microsoft Windows 2000, check out this document at http://people.freebsd.org/~murray/bsd_flier.html
