1.1 The Linux Operating System

   


Linux is a freely available multiuser, multitasking, multiprocessor, and multiplatform UNIX operating system. Its popularity and the number of users increase continually, making Linux an increasingly serious factor in the operating-systems market. Thanks to the freely available source code that everybody can obtain over the Internet and to the fact that everybody can participate in and contribute to the further development of the Linux system, many developers, all over the world, are constantly busy further developing this system, removing existing errors, and optimizing the system's performance.

The fact that most developers do this very time-consuming work for free in their spare time is a sign of the great fun working with Linux and mainly with the Linux kernel can be. As we progress in this book, we will try to pass some of this enthusiasm on to our readers. The large number of research projects at the University of Karlsruhe that have used, enhanced, or modified the Linux network architecture experienced a high motivation of all participating students. The reason was mainly that this offered them a way to participate in the "Linux movement."

The development of Linux was initiated by a student by the name of Linus B. Torvalds, in 1991. At that time, he worked five months on his idea of a new PC-based UNIX-like operating system, which he eventually made available for free on the Internet. It was intended to offer more functions than the Minix system designed by Andrew S. Tanenbaum, which was developed for teaching purposes only [Tane95]. With his message in the Minix newsgroup (see page 1), he set a movement in motion, the current result of which is one of the most stable and widely developed UNIX operating systems. Back then, Linus Torvalds planned only the development of a purely experimental system, but his idea further developed during the following years, so that Linux is now used successfully by many private people, corporations, and scientists alike. Mainly, the interoperability with other systems (Apple, MS-Windows) and the ability to run on many different platforms (Intel x86, MIPS, PA-RISC, IA64, Alpha, ARM, Sparc, PowerPC, M68, S390) make Linux one of the most popular operating systems.

Not only the extensive functionality of Linux, but also the freely accessible source code of this operating system, have convinced many private people and companies to use Linux. In addition, the German government, with its program for the support of open-source software, promotes the use of freely available programs with freely available source code. The main reason for this is seen not in the low procurement cost, but in the transparency of the software used. In fact, anyone can view the source code and investigate its functionality. Above all, anyone can check what perhaps security-relevant functionalities or errors are contained in an application or operating system. Especially with commercial systems and applications, there are often speculations that they could convey information about the user or the installed applications to the manufacturer.

You do not have such fears with freely developed software, where such a behavior would be noticed and published quickly. Normally, several developers work concurrently on an open-source project in a distributed way over the Internet, monitoring themselves implicitly. After all, free software is not aimed at maximizing the profit of a company or its shareholders. Its goal is to develop high-quality software for everybody. Linux is a very good example showing that freely developed software is not just the hobby of a handful of freaks, but leads to serious and extremely stable applications.

The authors of this book use Linux mainly for research work in the network area. The freely available source texts allow us to implement and evaluate new theories and protocols in real-world networks. For example, Linux was used to study various modifications of the TCP transport protocol [WeRW01, Ritt01], to develop a framework for the KIDS QoS support [Wehr01b], and to develop the high-resolution UKA-APIC timer [WeRi00].


       


    Linux Network Architecture
    Linux Network Architecture
    ISBN: 131777203
    EAN: N/A
    Year: 2004
    Pages: 187

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