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Firewall Fundamentals / Edition 1

Firewall Fundamentals / Edition 1

4.6 3
by Wes Noonan, Ido Dubrawsky

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ISBN-10: 1587052210

ISBN-13: 9781587052217

Pub. Date: 06/16/2006

Publisher: Cisco Press

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


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.

Product Details

Cisco Press
Publication date:
Fundamentals Series
Edition description:
New Edition
Product dimensions:
7.30(w) x 9.00(h) x 0.90(d)

Related Subjects

Table of Contents


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


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


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


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


User Datagram Protocol (UDP)

UDP Message Structure

UDP Datagram Header


Internet Control Message Protocol (ICMP)

ICMP Message Structure


Addressing in IP Networks

Physical Addresses

Logical Addresses

IP Addressing



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


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


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


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


Chapter 7 Linux-Based Firewalls

NetFilter Features

NetFilter Requirements

How NetFilter Works

Configuring NetFilter

IPTables Command-Line Tool

Firewall Builder



NetFilter Checklist


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


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


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


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


Common Firewall Management Tasks

Initial Configuration

Modifying the Configuration

Updating the Firewall Software


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


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


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




Part IV Appendixes

Appendix A Firewall and Security Tools

Appendix B Firewall and Security Resources


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Firewall Fundamentals 4.7 out of 5 based on 0 ratings. 3 reviews.
Anonymous More than 1 year ago
Guest More than 1 year ago
Firewalls have gone from a luxury to a necessity in the computer world, and today a thorough understanding of their function and setup is required reading for any serious networker, programmer, or computer operator. Firewall Fundamentals: An Introduction To Network And Computer Firewall Security addresses all issues, providing a through introduction to firewalls, how they protect, up to more advanced TCP/IP protocols and firewall configuration for Linux and other systems. From application proxy firewalls to security policies and rules, Firewall Fundamentals holds it all.
Guest More than 1 year ago
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 clear 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 that 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 and 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 firewalls 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 Maintenance any Firewall. 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 on 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 author¿s do everything to ensure a fair and equal play of the others I have mentioned before. I feel that if you where 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 collectio