21.1. Introduction21.2. Vulnerabilities in Network Protocols21.2.1. Attacks on Local Networks21.2.2. Attacks Using Internet Protocols and Mechanisms21.2.2.1. SYN Flooding21.2.2.2. Smurfing21.2.2.3. Distributed Denial of Service Attacks21.2.2.4. Spam21.2.2.5. DNS Security and Pharming21.3. Trojans, Viruses, Worms and Rootkits21.3.1. Early History of Malicious Code21.3.2. The Internet Worm21.3.3. How Viruses and Worms Work21.3.4. The History of Malware21.3.5. Countermeasures21.4. Defense Against Network Attack21.4.1. Configuration Management and Operational Security21.4.2. Filtering: Firewalls, Spam Filters, Censorware and Wiretaps21.4.2.1. Packet Filtering21.4.2.2. Circuit Gateways21.4.2.3. Application Relays21.4.2.4. Ingress Versus Egress Filtering21.4.2.5. Architecture21.4.3. Intrusion Detection21.4.3.1. Types of Intrusion Detection21.4.3.2. General Limitations of Intrusion Detection21.4.3.3. Specific Problems Detecting Network Attacks21.4.4. Encryption21.4.4.1. SSH21.4.4.2. WiFi21.4.4.3. Bluetooth21.4.4.4. HomePlug21.4.4.5. IPsec21.4.4.6. TLS21.4.4.7. PKI21.5. Topology21.6. Summary21.7. Research Problems21.8. Further Reading