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Security has become a major concern for every network administrator. Nearly every day we are bombarded with news articles describing yet another high-profile company that has fallen prey to a network-based attack. To fill in the occasional gap, we hear about new viruses that have been found “in the wild” or about additional software vulnerabilities that someone has figured out how to exploit for personal gain. The network security field has not always been this crazy. Most of us can remember a time when securing a network environment was a far easier task. As long as every user had a password and the correct levels of file. | Introduction CHAPTER 1 Why Secure Your Network Thinking like an Attacker Attacker vs. Hacker Why Would Someone Want to Ruin My Day Attacks from Within External Attacks Chapter Worksheet Summary CHAPTER 2 How Much Security Do You Need Performing a Risk Analysis What Assets Do I Need to Protect From What Sources Am I Trying to Protect These Assets Who May Wish to Compromise Our Network What Is the Likelihood of an Attack What Is the Immediate Cost What Are the Long-Term Recovery Costs How Can I Protect My Assets Cost-Effectively Am I Governed by a Regulatory Body Budgeting Your Security Precautions Documenting Your Findings Developing a Security Policy Security Policy Basics What Makes a Good Security Usage Policy Accessibility Defining Security Goals Defining Each Issue Your Organization s Position Justifying the Policy When Does the Issue Apply Roles and Responsibilities Consequences of Noncompliance For More Information. Level of Privacy Issues Not Specifically Defined Example of a Good Policy Statement Summary CHAPTER 3 Understanding How Network Systems Communicate The Anatomy of a Frame of Data Ethernet Frames The Frame Header Section A Protocol s Job The OSI Model Physical Layer Data Link Layer Network Layer Transport Layer Session Layer Presentation Layer Application Layer How the OSI Model Works More on the Network Layer Routers Routing Tables Static Routing Distance Vector Routing Link State Routing Connectionless and Connection-Oriented Communications Connection-Oriented Communications Network Services File Transfer Protocol FTP The Special Case Other IP Services Boot Protocol bootp and Dynamic Host Configuration Protocol DHCP Domain Name Services DNS Gopher Hypertext Transfer Protocol HTTP Post Office Protocol POP Internet Message Access Protocol Version 4 IMAP4 Network File System NFS Network News Transfer Protocol NNTP NetBIOS over IP Simple Mail Transfer Protocol SMTP Simple Network Management Protocol SNMP Telnet WHOIS Upper Layer Communications .
