Chapter 10. Network Security

The invention of computers made the need for security of digital information a critical issue. Advances in the field of computer networks have made information security even more important. Computer systems have to be equipped with mechanisms for securing data. Computer networks need provisions that secure data from possible intrusions. Security is especially crucial in wireless networks, as a wireless medium, by its nature, is vulnerable to intrusions and attacks. This chapter focuses on network security . The following major topics in network security are covered:

• Overview of network security: elements and threats

• Overview of security methods

• Secret-key encryption protocols

• Public-key encryption protocols

• Authentication: message digest and digital signatures

• Security of IP and wireless networks

• Firewalls

We begin by identifying and classifying types of network threats, hackers, and attacks, including DNS hacking attacks and router attacks. Network security can be divided into two broad categories: cryptographic techniques and authentication techniques (verification). Both secret-key and public-key encryption protocols are presented. We then discuss message authentication and digital signature methods, through which a receiver can be assured that an incoming message is from whom it says it is.

We then consider several standardized security techniques, such as IPsec, and the security of wireless networks and IEEE 802.11 standards, as well as firewalls, or devices designed to protect a network. Finally, we present a case study on the security of wireless networks.