Linux History

Lesson 01 : Linux History

In this lesson , we will learn about Linux history and open source software.In 1991 in Helsinki University, Finland Linux was born by Linus Torvalds where he began developing a UNIX-like kernel.He first announced his work in a now-famous e-mail message on the comp.os.minix mailing list :

From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds)
Newsgroups: comp.os.minix
Subject: What would you like to see most in minix?
Summary: small poll for my new operating system
Message-ID:1991AUG25.205708.9541@klaava.Helsinki.FI
Date: 25 Aug 91 20:57:08 GMT
Organization: University of Helsinki

Hello everybody out there using minix -

I'm doing a (free) operating system (just a hobby, won't be big and
professional like gnu) for 386(486) AT clones. This has been brewing
since april, and is starting to get ready. I'd like any feedback on
things people like/dislike in minix, as my OS resembles it somewhat
(same physical layout of the file-system (due to practical reasons)
among other things).

I've currently ported bash(1.08) and gcc(1.40), and things seem to work.
This implies that I'll get something practical within a few months, and
I'd like to know what features most people would want. Any suggestions
are welcome, but I won't promise I'll implement them :-)

Linus (torvalds@kruuna.helsinki.fi)

PS. Yes - it's free of any minix code, and it has a multi-threaded fs.
It is NOT protable (uses 386 task switching etc), and it probably never
will support anything other than AT-harddisks, as that's all I have :-(.

Kernel is the core of the Linux operating system and it is layer between the software and the hardware that manages and controls resources such as processor and memory.

Despite of the humbleness of the email, Torvald’s kernel was to become a professional kernel held in the highest regard in the computing world. Today, Torvald’s kernel, along with tools from the GNU project and elements from other open source projects (X from Xorg, for example), make up the core of Red Hat Enterprise Linux and other Linux distributions, such as the Fedora Project.

Open source software:

Software whose source code is freely available to all is known as open source software ( OSS ). The purpose of OSS is to encourage collaborative work, often through broad participation in software projects across business and geographical boundaries.

Two main groups that promote the benefits of OSS define it in different ways. The Open Source Initiative (OSI) defines OSS as having the following features:

• The software and source code must be freely distributable

• All users must be able to modify the source code and create derived works

• To maintain the integrity of the original author’s work, the license may require that modifications to the code be provided in patch form

• The license has to be inherited, so that those who receive a distribution are subject to the identical terms

• The license must be nondiscriminatory with respect to persons, groups, or fields of endeavor; it must be free of restrictions that can limit the license. For example, it may not require that the software be a part of a particular distribution; it must not restrict other non-OSS software and it may not require the use of technology to apply the license.

See http://www.opensource.org/docs/definition.php for specific terms.
An alternative definition of open source software comes from the free software movement, which emphasizes the ethical aspects of software and source code availability. As presented by the GNU Project and the Free Software Foundation at http://www.gnu.org/philosophy/free-sw.html, software is free if it satisfies four freedoms:

• The software must be freely executable for any purpose
• The source code must be available so that others can study how it works
• The software must be freely redistributable
• All users must be free to modify the software

Still other licenses, such as the Berkeley Software Distribution (BSD) license, enforce other interpretations of open source. For example, the BSD license does not enforce inheritance, meaning that BSD-licensed software may be incorporated into closed-source projects.

Concepts in IP Security

No topic related to the Internet, with the possible exceptions of the fl ee availability of pornography and the plague of unwanted spam email, has received more attention in the mainstream media than “ security. ” For the average user the concerns are predominantly viruses that may infect their personal computers, causing inconvenience or damage to their data. Increasingly we also hear about white-collar e-criminals who steal personal fi nancial details or defraud large institutions after illegally gaining entry to their computer systems. We are also now all familiar with catastrophic failures of parts of the Internet. Although these are sometimes caused by bugs in core components (such as routers) or by the perennial backhoe cutting a cable or fi ber, they are increasingly the responsibility of individuals whose sole joy is to pit their wits against those who maintain the Internet.

Sometimes known as hackers, these people attempt to penetrate network security, or cause disruption through denial of service attacks for a range of motives. Corporate espionage is of relatively little concern to most people, but within every forward-looking company there is a person or a department responsible for keeping the company’s secrets safe. At the same time, the populist war against terrorism invokes contradictory requirements—that the government should be able to keep its information private while at the same time examining the affairs of suspects without them being able to hide their communications. Whatever the rights and wrongs of the politics and sociology, Internet security is a growth industgry. This chapter provides an overview of some of the issues and shows the workings of the key security protocols.

It introduces the security algorithms without going into the details of the sophisticated mathematics behind encryption algorithms or key generation techniques. For this type of information the reader is referred to the reference material listed at the end of the chapter. The first sections of the chapter examine the need for security, where within the network it can be applied, and the techniques that may be used to protect data that is stored in or transmitted across the network. There then follows a detailed examination of two key security protocols: IPsec, which provides security at the IP packet level, and Transport Layer Security (TLS), which operates at the transport layer and provides the Secure Sockets Layer (SSL). After a brief discussion of some of the ways to secure Hypertext Transfer Protocol (HTTP) transactions, which are fundamental to the operation of web-based commerce, the chapter describes how hashing and encryption algorithms are used in conjunction with keys to detect modification of data or to hide it completely—the Message Digest Five (MDS) hashing algorithm is presented as the simplest example. The chapter concludes with an examination of how security keys may be securely exchanged across the network so that they may be used to decrypt or verify transmitted data.