Security in Networks
In this chapter
· Networks vs. stand-alone applications and environments: differences and similarities
· Threats against networked applications, including denial of service, web site defacements, malicious mobile code, and protocol attacks
· Controls against network attacks: physical security, policies and procedures, and a range of technical controls
· Firewalls: design, capabilities, limitations
· Intrusion detection systems
· Private e-mail: PGP and S/MIME
Networkstheir design, development, and usageare critical to our style of computing. We interact with networks daily, when we perform banking transactions, make telephone calls, or ride trains and planes. The utility companies use networks to track electricity or water usage and bill for it. When we pay for groceries or gasoline, networks enable our credit or debit card transactions and billing. Life without networks would be considerably less convenient, and many activities would be impossible. Not surprisingly, then, computing networks are attackers' targets of choice. Because of their actual and potential impact, network attacks attract the attention of journalists, managers, auditors, and the general public. For example, when you read the daily newspapers, you are likely to find a story about a network-based attack at least every month. The coverage itself evokes a sense of evil, using terms such as hijacking, distributed denial of service, and our familiar friends viruses, worms, and Trojan horses. Because any large-scale attack is likely to put thousands of computing systems at risk, with potential losses well into the millions of dollars, network attacks make good copy.
The media coverage is more than hype; network attacks are critical problems. Fortunately, your bank, your utility company, and even your Internet service provider take network security very seriously. Because they do, they are vigilant about applying the most current and most effective controls to their systems. Of equal importance, these organizations continually assess their risks and learn about the latest attack types and defense mechanisms so that they can maintain the protection of their networks.
In this chapter we describe what makes a network similar to and different from an application program or an operating system, which you have studied in earlier chapters. In investigating networks, you will learn how the concepts of confidentiality, integrity, and availability apply in networked settings. At the same time, you will see that the basic notions of identification and authentication, access control, accountability, and assurance are the basis for network security, just as they have been in other settings.
Networking is growing and changing perhaps even faster than other computing disciplines. Consequently, this chapter is unlikely to present you with the most current technology, the latest attack, or the newest defense mechanism; you can read about those in daily newspapers and at web sites. But the novelty and change build on what we know today: the fundamental concepts, threats, and controls for networks. By developing an understanding of the basics, you can absorb the most current news quickly and easily. More importantly, your understanding can assist you in building, protecting, and using networks.