Firewall Fundamentals
- By Wes Noonan, Ido Dubrawsky
- Published Jun 2, 2006 by Cisco Press.
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- Copyright 2006
- Pages: 408
- Edition: 1st
- eBook (Watermarked)
- ISBN-10: 0-13-279834-4
- ISBN-13: 978-0-13-279834-1
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.
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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