System administrators need to stay ahead of new security vulnerabilities that leave their networks exposed every day. A firewall and an intrusion detection systems (IDS) are two important weapons in that fight, enabling you to proactively deny access and monitor network traffic for signs of an attack.
Linux Firewalls discusses the technical details of the iptables firewall and the Netfilter framework that are built into the Linux kernel, and it explains how they provide strong filtering, Network Address Translation (NAT), state tracking, and application layer inspection capabilities that rival many commercial tools. You'll learn how to deploy iptables as an IDS with psad and fwsnort and how to build a strong, passive authentication layer around iptables with fwknop.
Concrete examples illustrate concepts such as firewall log analysis and policies, passive network authentication and authorization, exploit packet traces, Snort ruleset emulation, and more with coverage of these topics:
Passive network authentication and OS fingerprinting
iptables log analysis and policies
Application layer attack detection with the iptables string match extension
Building an iptables ruleset that emulates a Snort ruleset
Port knocking vs. Single Packet Authorization (SPA)
Tools for visualizing iptables logs
Perl and C code snippets offer practical examples that will help you to maximize your deployment of Linux firewalls. If you're responsible for keeping a network secure, you'll find Linux Firewalls invaluable in your attempt to understand attacks and use iptables-along with psad and fwsnort-to detect and even prevent compromises.
Chapter 1 CARE AND FEEDING OF IPTABLES
iptables
Packet Filtering with iptables
Installing iptables
Kernel Configuration
Security and Minimal Compilation
Kernel Compilation and Installation
Installing the iptables Userland Binaries
Default iptables Policy
Concluding Thoughts
Chapter 2 NETWORK LAYER ATTACKS AND DEFENSE
Logging Network Layer Headers with iptables
Network Layer Attack Definitions
Abusing the Network Layer
Network Layer Responses
Chapter 3 TRANSPORT LAYER ATTACKS AND DEFENSE
Logging Transport Layer Headers with iptables
Transport Layer Attack Definitions
Abusing the Transport Layer
Transport Layer Responses
Chapter 4 APPLICATION LAYER ATTACKS AND DEFENSE
Application Layer String Matching with iptables
Application Layer Attack Definitions
Abusing the Application Layer
Encryption and Application Encodings
Application Layer Responses
Chapter 5 INTRODUCING PSAD: THE PORT SCAN ATTACK DETECTOR
Michael Rash is a Security Architect on the Dragon Intrusion DetectionSystem with Enterasys Networks, Inc., and is a frequent contributor toopen source projects. As the creator of psad, fwknop, and fwsnort, Rashis an expert on firewalls, IDSs, OS fingerprinting, and the Snort ruleslanguage. He is co-author of the book Snort 2.1 Intrusion Detection,lead-author and technical editor of the book Intrusion Prevention andActive Response, and has written security articles for Linux Journal,SysAdmin, and ;login:.