The environment in which your network resides has become increasingly hostile. It is important to clarify who creates the majority of the problems. Hackers are not usually malicious. They use their skill to find and fix vulnerabilities. Crackers and script kiddies are malicious. The difference is that a hacker builds while a cracker destroys. Crackers and script kiddies use software that allows them to detect open systems, break into them, and establish root-level access on a network. Virus construction kits make it possible to tailor new electronic viruses on demand. Spam and e-mail scams make it simple to propagate these to unsuspecting users worldwide.

This chapter examines the several well-known threats to network security. These include the following:

Crackers and script kiddies (referred to collectively as attackers in this chapter) not only launch attacks for sport but to cause criminal damage. Malicious behavior is illegal and severe penalties are the consequence. This chapter will help you understand the threats and vulnerabilities of the network in order to defend against them.


The focus of this chapter is on specific attacks that can be launched against a network. It is important to learn what these attacks involve and how they are implemented in order to defend the network. A thorough understanding of data transfer is helpful. The student will study the OSI reference model and TCP/IP to understand how data travels since an attack can occur at any level. In addition, the student will learn the vulnerabilities of wireless networks and the steps required to safeguard the network.

Upon completion of this chapter, the student should be able to:

  1. Explain the fundamental concepts and best practices related to authentication and authorization
  2. Explain the fundamental concepts and best practices related to access control
  3. Implement appropriate security controls when performing account management