Firewall Fundamentals

The essential guide to understanding and using firewalls to protect personal computers and your network

• An easy-to-read introduction to the most commonly deployed network security device
• Understand the threats firewalls are designed to protect against
• Learn basic firewall architectures, practical deployment scenarios, and common management and troubleshooting tasks
• Includes configuration, deployment, and management checklists

Increasing reliance on the Internet in both work and home environments has radically increased the vulnerability of computing systems to attack from a wide variety of threats. Firewall technology continues to be the most prevalent form of protection against existing and new threats to computers and networks. A full understanding of what firewalls can do, how they can be deployed to maximum effect, and the differences among firewall types can make the difference between continued network integrity and complete network or computer failure. Firewall Fundamentals introduces readers to firewall concepts and explores various commercial and open source firewall implementations--including Cisco, Linksys, and Linux--allowing network administrators and small office/home office computer users to effectively choose and configure their devices. Firewall Fundamentals is written in clear and easy-to-understand language and helps novice users understand what firewalls are and how and where they are used. It introduces various types of firewalls, first conceptually and then by explaining how different firewall implementations actually work. It also provides numerous implementation examples, demonstrating the use of firewalls in both personal and business-related scenarios, and explains how a firewall should be installed and configured. Additionally, generic firewall troubleshooting methodologies and common management tasks are clearly defined and explained.

Praise For Firewall Fundamentals

Firewall Fundamentals
Reviewer Name: Joel E. Natt, Information Security Engineer

Firewall Fundamentals provides what I see as the first clear book in many years on the oldest known protection for the Information Technology field. Authors Wes Noonan and Ido Dubrawsky take the concepts of protection at the basic level and slowly walk the reader through protection and defense from the introduction of threats to the details of advanced firewalls like the Cisco PIX and ASA appliances to Microsoft’s ISA application. While this book may to be advanced in nature, it explains in detail the simple items that make the understanding of firewalls and their technology important. Even from the goal of the book “…personal and desktop…” where the authors clearly state that no level will be untouched does this book make one feel comfortable and unafraid.

Considering that this is a Cisco Press book it surprised me the amount of non-Cisco detail the authors’ included, from Checkpoint and Microsoft ISA in the larger areas to Trend-Micro in the smaller areas. These guys ensured in this book a level of detail and understanding that will guarantee a complete read; even a security engineer like myself who has learned the advanced concepts and deployment methods/reasons for security gained new insight into the world I work in. For both Noonan and Dubrawsky present the items I sometimes miss, the obvious and clear issues that the regular individuals encounter and need to help them.

Noonan and Dubrawsky start with the simple items and basic concepts slowly adding to them while not forgetting the assumed reader. This book is divided into four sections including the Appendixes: The first of the major section as always the Introduction which covers the basics from what a threat is to the difference between a personal (computer) based firewall to a network firewall.

After the basics are covered the authors’ begin moving into the how of firewall technology from the personal computer to the common home office like Linksys and finally into the realm of small office and hardware that include the Cisco platforms. While these chapters may appear to focus more on the Cisco products, they do include important other chapters that deal with items like where a firewall belongs within the network. Within this section of the book we see items as mentioned like the Linksys and Cisco products, but we also see NetFilter and other freeware and pay products including Microsoft’s ISA and Checkpoint mentioned, configured and discussed in detail. Within Chapter 7 the Linux products that are slowly advancing in the industry due to their cost and availability are detailed with the NetFilter product. Flow-charts and diagrams again help to explain not only this product, but the key concepts behind firewall technologies and examples of scripting help individuals learn and understanding what should be occurring with the product.

Finally the last key section deals with the importance of Managing and Maintaining Firewalls. From policy management to troubleshooting they do not leave anything out. I personally found the chapter entitled “What is My Firewall Telling Me?” very different from what I would expect in a simple how to read the logs chapter. The authors took time to explain the concepts of logging, the importance and different methods to read the log. Again they showed that this is not a book that is Cisco centric or Cisco heavy by using products and screen shots of non-Cisco items like Microsoft and NetIQ.

What this book is missing is a disclaimer that while published by Cisco Press it is not entirely Cisco centric and this is a good thing. Yes, as many people know Cisco is a large player in the field of networking and information security. These authors do everything to ensure a fair and equal play of the others I have mentioned before. I feel that if you are looking for a book to help anyone with a small or home office environment protect it, this is the book you need. While I found adding it to my collection a positive and enjoyable experience, I can only hope that you will too.

Online Sample Chapter

Broadband Routers and Firewalls

Sample Chapter(s)

Download - 1.1 MB -- Chapter 5: Broadband Routers and Firewalls

Index

Download - 1.4 MB -- Index

Table of Contents

      Introduction

Part 1      Introduction to Firewalls3

Chapter 1 Introduction to Firewalls

What Is a Firewall?

What Can Firewalls Do?

     Firewalls Manage and Control Network Traffic

     Firewalls Authenticate Access

     Firewalls Act as an Intermediary

     Firewalls Protect Resources

     Firewalls Record and Report on Events

What Are the Threats?

     Targeted Versus Untargeted Attacks

     Viruses, Worms, and Trojans

     Malicious Content and Malware

     Denial of Service

     Zombies

     Compromise of Personal Information and Spyware

     Social Engineering

     New Attack Vectors

     Insecure/Poorly Designed Applications

What Are the Motives?

Security Policies

     Examples of Security Policies

     Firewalls and Trust

Determining If You Need a Firewall

Summary

Chapter 2 Firewall Basics

Firewall Taxonomy

     Personal Firewalls

     Network Firewalls

Firewall Products

     Software Firewalls

     Appliance Firewalls

     Integrated Firewalls

Firewall Technologies

     Personal Firewalls

     Packet Filters

     NAT Firewalls

     Circuit-Level Firewalls

     Proxy Firewalls

     Stateful Firewalls

     Transparent Firewalls

     Virtual Firewalls

Open and Closed Source Firewalls

Summary

Chapter 3 TCP/IP for Firewalls

Protocols, Services, and Applications

     The OSI Model

     The Department of Defense (DoD) Model

     How Firewalls Use Protocols, Applications, and Services

Internet Protocol (IP)

     IP Packet Structure

     The IP Packet Header

     Bad IP Packets

Transmission Control Protocol (TCP)

     TCP Segment Structure

     TCP Segment Header

     Bad TCP

User Datagram Protocol (UDP)

     UDP Message Structure

     UDP Datagram Header

     Bad UDP

Internet Control Message Protocol (ICMP)

     ICMP Message Structure

     Bad ICMP

Addressing in IP Networks

     Physical Addresses

     Logical Addresses

     IP Addressing

     Subnets

     IPv6

Network Address Translation (NAT)

NAT Implementations

     NAT and IPsec: The Issues and the Solutions

Broadcast and Multicast

IP Services

IP Routing

     Types of Routing

     How the IP Routing Process Works

     Different Classes of Routing Protocols

     Common Routing Protocols

Applications Using IP

     Common Applications Using IP

     Less-Common Applications Using IP

     Protocols Used to Implement Security

Summary

Part II     How Firewalls Work

Chapter 4 Personal Firewalls: Windows Firewall and Trend Micro’s PC-cillin

Windows Firewall and Windows XP

     How Windows Firewall Works

     Configuring Windows Firewall

     Windows Firewall Features

     Windows Firewall Checklist

Trend Micro’s PC-cillin Firewall Feature

     PC-cillin Requirements

     How the Trend Micro Firewall Works

     Configuring the Trend Micro Firewall

     Trend Micro Firewall Features

     Trend Micro Firewall Checklist

Summary

Chapter 5 Broadband Routers and Firewalls

How Broadband Routers and Firewalls Work

Linksys Broadband Routers/Firewalls

     Security and Filtering Features

     Routing Features

     Management and Administration Features

     Miscellaneous Features

Linksys Requirements

How the Linksys Router/Firewall Works

     Filtering Traffic from External Sources

     Filtering Traffic from Internal Sources

Configuring Linksys

     Configuring Basic Setup

     Configuring Security

     Configuring Applications & Gaming

     Configuring Administration

Linksys Checklist

Summary

Chapter 6 Cisco PIX Firewall and ASA Security Appliance

PIX/ASA Features

Choosing Between the PIX and the ASA

Cisco PIX Firewall and ASA Models

     SOHO Solution

     Medium- to Large-Office Solution

     Enterprise Office and Service Provider Solution

How the PIX/ASA Firewall Works

     Firewall Security Policy

     Firewall Modes of Operation

     Stateful Inspection

Configuring the Cisco PIX/ASA

     Assigning IP Addresses to the Firewall Interfaces

     Configuring the Firewall Name, Domain Name, and Passwords

     Configuring the Firewall Routing Settings

     Configuring the Firewall for Remote Management Access

     Configuring NAT Settings for Outbound Access

     Configuring the ACLs

     Configuring Logging on the Firewall

PIX/ASA Checklist

Summary

Chapter 7 Linux-Based Firewalls

NetFilter Features

NetFilter Requirements

How NetFilter Works

Configuring NetFilter

     IPTables Command-Line Tool

     Firewall Builder

     Firestarter

     Webmin

NetFilter Checklist

Summary

Chapter 8 Application Proxy Firewalls

Application Layer Filtering

     How Application Filtering Works

     The Difference Between Application Filtering and Deep Packet Inspection

Proxy Server Functionality

Limitations of Application Proxy Firewalls

Microsoft ISA Server 2004 Firewall

     Microsoft ISA Server 2004 Features

     Microsoft ISA Server 2004 Requirements and Preparation

     How the Microsoft ISA Server 2004 Firewall Works

     Microsoft ISA Server 2004 Checklist

Summary

Chapter 9 Where Firewalls Fit in a Network

Different Types of Office Requirements

     Central Office

     Remote Office

Single-Firewall Architectures

     Internet Firewall with a Single DMZ

     Internet Firewall with Multiple DMZs

     Internet-Screening Firewall (No DMZ)

Dual-Firewall Architecture

The Firewall System

     Single-Firewall System

     Dual-Firewall System

Where Personal/Desktop Firewalls Fit in a Network

Where Application Firewalls Fit in a Network

Firewalls and VLANs

     Virtual Firewalls

Using Firewalls to Segment Internal Resources

     Protecting Sensitive Internal Resources

     Protecting from WAN or Remote-Access Requests

     Protecting Individual Internal Resources

     Be Realistic When Implementing Internal Firewalls

High-Availability Firewall Designs

Summary

Part III    Managing and Maintaining Firewalls

Chapter 10 Firewall Security Policies

Written Security Policies

     The Difference Between Policies, Standards, Guidelines, and Procedures

     Security Policy Format

     Common Security Policies

     Firewall Security Policy

Firewall Policies/Rulesets

     Ingress Filters

     Egress Filters

     Management-Access Ruleset

Summary

Chapter 11 Managing Firewalls

Default Passwords

Maintaining the Underlying Platform

Firewall Management Interface

     Managing Firewalls with a CLI

     Managing Firewalls with a GUI

     Interface Preference

Management Access

     In-Band Management

     Out-of-Band Management

     Telnet vs. SSH

     HTTP vs. HTTPS

Common Firewall Management Tasks

     Initial Configuration

     Modifying the Configuration

     Updating the Firewall Software

Summary

Chapter 12 What Is My Firewall Telling Me?

Firewalls and Logging

     The Syslog Protocol

     Proprietary Logging Methods

     Why Logging Is Important

Firewall Log Review and Analysis

     What to Look for in Firewall Logs

     Cisco Secure PIX Firewall Syslog Event Baseline

Firewall Forensics

     The Value (or Not) of IP Addresses

     Deciphering Port Numbers

     Securing the Firewall

Summary

Chapter 13 Troubleshooting Firewalls

Developing a Troubleshooting Checklist

     Step 1: Verify the Problem Reported

     Step 2: Test Connectivity

     Step 3: Physically Check the Firewall

     Step 4: Check for Recent Changes

     Step 5: Check the Firewall Logs for Errors

     Step 6: Verify the Firewall Configuration

     Step 7: Verify the Firewall Ruleset

     Step 8: Verify That Any Dependent, Non-Firewall-Specific
Systems Are Not the Culprit

     Step 9: Monitor the Network Traffic

Basic Firewall Troubleshooting

     Troubleshooting Connectivity Through the Firewall

     Troubleshooting Connectivity to the Firewall

Advanced Firewall Troubleshooting

Troubleshooting Example

Summary

Chapter 14 Going Beyond Basic Firewall Features

Content Filtering

     Implementing a URL Filter

     Maintaining URL Filters

     What to Do If. . .

Performing Application Filtering

     Applications That Are Hard to Firewall

Intrusion Detection and Prevention

     Overview of IDS

Virtual Private Networks

     IPsec VPNs

     SSL VPNs

Summary

Endnotes

Part IV     Appendixes

Appendix A Firewall and Security Tools

Appendix B Firewall and Security Resources

 

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