linux basics & Hacking Linux Systems

linux basics & Hacking Linux Systems

History of Linux OS

Linux is a Unix-like computer operating system assembled under the model of free and open-source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds.The Free Software Foundation uses the name GNU/Linux to describe the operating system, which has led to some controversy.

Linux was originally developed for personal computers based on the Intel x86 architecture, but has since been ported to more platforms than any other operating system.[18] Because of the dominance of Android on smartphones, Linux has the largest installed base of all general-purpose operating systems. Linux is also the leading operating system on servers and other big iron systems such as mainframe computers, and is used on 99.6% of the TOP500 supercomputers.It is used by around 2.3% of desktop computers. The Chromebook, which runs on Chrome OS, dominates the US K–12 education market and represents nearly 20% of the sub-$300 notebook sales in the US. Linux also runs on embedded systems – devices whose operating system is typically built into the firmware and is highly tailored to the system. This includes TiVo and similar DVR devices, network routers, facility automation controls, televisions, video game consoles and smartwatches.Many smartphones and tablet computers run Android and other Linux derivatives

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Quick Note on  Linux

Linux is the most widely used server operating system especially for web servers. It is open source; this means anybody can have access to the source code. This makes it less secure compared to other operating systems as attackers can study the source code to find vulnerabilities. Linux Hacking is about exploiting these vulnerabilities to gain unauthorized access to a system.
A number of you have written me regarding which operating system is best for hacking. I'll start by saying that nearly every professional and expert hacker uses Linux or Unix. Although some hacks can be done with Windows and Mac OS, nearly all of the hacking tools are developed specifically for Linux.

Linux Hacking Tools

• Nessus– this tool can be used to scan configuration settings, patches, and networks etc. it can be found at http://www.tenable.com/products/nessus
• NMap. This tool can be used to monitor hosts that are running on the server and the services that they are utilizing. It can also be used to scan for ports. It can be found at http://nmap.org/
• SARA – SARA is the acronym for Security Auditor’s Research Assistant. As the name implies, this tool can be used to audit networks against threats such as SQL Injection, XSS etc. it can be found at http://www-arc.com/sara/sara.html
• The above list is not exhaustive; it gives you an idea of the tools available for hacking Linux systems.

How to prevent  Linux hacks

Linux Hacking takes advantage of the vulnerabilities in the operating system. An organization can adopt the following policy to protect itself against such attacks.

Patch management– patches fix bugs that attackers exploit to compromise a system. A good patch management policy will ensure that you constantly apply relevant patches to your system.
Proper OS configuration– other exploits take advantage of the weaknesses in the configuration of the server. Inactive user names and daemons should be disabled. Default settings such as common passwords to application, default user names and some port numbers should be changed.
Intrusion Detection System– such tools can be used to detect unauthorized access to the system. Some tools have the ability to detect and prevent such attacks.

Hacking Activity: Hack a Linux system using PHP

In this practical scenario, we will provide you with basic information on how you can use PHP to compromise a Linux. We are not going to target any victim. If you want to try it out, you can install LAMPP on your local machine.

PHP comes with two functions that can be used to execute Linux commands. It has exec() and shell_exec() functions. The function exec() returns the last line of the command output while the shell_exec() returns the whole result of the command as string.

Summary

• Linux is a popular operating system for servers, desktops, tablets and mobile devices.
• Linux is open source and the source code can be obtained by anyone. This makes it easy to spot the vulnerabilities.
• Basic and networking commands are valuable to Linux hackers.
• Vulnerabilities are weakness that can be exploited to compromise a system.
• A good security can help to protect a system from been compromised by an attacker.