الفهرس 
Chapter 1Only 14 pages are availabe for public view
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Abstract
Recently various attacks are being observed on different web servers. Those responsible for these attacks can be any level of hacker, and it can vary from beginner to professional hackers. The reasons for these attacks are unknown and not specified. They may be stealing visitors’ data, modifying the site’s content, disrupting the execution of tasks on the website, or causing any physical damage to the web server. One of the most common attacks is a denial of service (DoS) attack, which is executed by a single hacker,this hacker sends a flood of difficult-to-execute commands to the target server, which
may prevent the visitors from reaching a resource, or hanging the server machines to be
unresponsive to its users. This type of attack can be performed using any simple and
general purpose programming language. Because of the ease of executing this attack,
it can be automated and executed by network of different bot scripts, another variation
for this attack is called distributed denial of service (DDoS attack), and such network of
bots is called botnets. These attacks are the focus of attention of many large companies
of information security.