Preface
I Network Security
1. Wiry Internet Firewalls?
What Are You Trying to Protect?
What Are You Trying to Protect Against?
Who Do You Trust?
How Can You Protect Your Site?
What Is an Internet Firewall?
Religious Arguments
2. Internet Services
Secure Services and Safe Services
The World Wide Web
Electronic Mail and News
File Transfer, File Sharing, and Printing
Remote Access
Real-Time Conferencing Services
Naming and Directory Services
Authentication and Auditing Services
Administrative Services
Databases
Games
3. Security Strategies
Least Privilege
Defense in Depth
Choke Point
Weakest Link
Fail-Safe Stance
Universal Participation
Diversity of Defense
Simplicity-
Security Through Obscurity
II Building Firewalls
4. Packets and Protocols
What Does a Packet Look Like?
IP
Protocols Above IP
Protocols Below IP
Application Layer Protocols
IP Version 6
Non-IP Protocols
Attacks Based on Low-Level Protocol Details
5. Firewall Technologies
Some Firewall Definitions
Packet Filtering
Proxy Services
Network Address Translation
Virtual Private Networks
6. Firewall Architectures
Single-Box Architectures
Screened Host Architectures
Screened Subnet Architectures
Architectures with Multiple Screened Subnets
Variations on Firewall Architectures
Terminal Servers and Modem Pools
Internal Firewalls
7. Firewall Design
Define Your Needs
Evaluate the Available Products
Put Everything Together
8. Packet Filtering
What Can You Do with Packet Filtering?
Configuring a Packet Filtering Router
What Does the Router Do with Packets?
Packet Filtering Tips and Tricks
Conventions for Packet Filtering Rules
Filtering by Address
Filtering by Service
Choosing a Packet Filtering Router
Packet Filtering Implementations for General-Purpose Computers
Where to Do Packet Filtering
What Rules Should You Use?
Putting It All Together
9. Proxy Systems
Why Proxying?
How Proxying Works
Proxy Server Terminology
Proxying Without a Proxy Server
Using SOCKS for Proxying
Using the TIS Internet Firewall Toolkit for Proxying
Using Microsoft Proxy Server
What If You Can't Proxy?
10. Bastion Hosts
General Principles
Special Kinds of Bastion Hosts
Choosing a Machine
Choosing a Physical Location
Locating Bastion Hosts on the Network
Selecting Services Provided by a Bastion Host
Disabling User Accounts on Bastion Hosts
Building a Bastion Host
Securing the Machine
Disabling Nonrequired Services
Operating the Bastion Host
Protecting the Machine and Backups
11. Unix and Linux Bastion Hosts
Which Version of Unix?
Securing Unix
Disabling Nonrequired Services
Installing and Modifying Services
Reconfiguring for Production
Running a Security Audit
12. Windows NT and Windows 2000 Bastion Hosts
Approaches to Building Windows NT Bastion Hosts
Which Version of Windows NT?
Securing Windows NT
Disabling Nonrequired Services
Installing and Modifying Services
III Internet Services
13. Internet Services and Firewalls
Attacks Against Internet Services
Evaluating the Risks of a Service
Analyzing Other Protocols
What Makes a Good Firewalled Service?
Choosing Security-Critical Programs
Controlling Unsafe Configurations
14. Intermediary Protocols
Remote Procedure Call (RPC)
Distributed Component Object Model (DCOM)
NetBIOS over TCP/IP (NetBT)
Common Internet File System (CIFS) and Server
Message Block (SMB)
Common Object Request Broker Architecture (CORBA)
and Internet Inter-Orb Protocol (IIOP)
ToolTalk
Transport Layer Security (TLS) and Secure Socket Layer (SSL)
The Generic Security Services API (GSSAPI)
IPsec
Remote Access Service (RAS)
Point-to-Point Tunneling Protocol (PPTP)
Layer 2 Transport Protocol (L2TP)
15. The World Wide Web
HTTP Server Security
HTTP Client Security
HTTP
Mobile Code and Web-Related Languages
Cache Communication Protocols
Push Technologies
RealAudio and RealVideo
Gopher and WAIS
16. Electronic Mail and News
Electronic Mail
Simple Mail Transfer Protocol (SMTP)
Other Mail Transfer Protocols
Microsoft Exchange
Lotus Notes and Domino
Post Office Protocol (POP)
Internet Message Access Protocol (IMAP)
Microsoft Messaging API (MAPI)
Network News Transfer Protocol (NNTP)
17. File Transfer, File Sharing, and Printing
File Transfer Protocol (FTP)
Trivial File Transfer Protocol (TFTP)
Network File System (NFS)
File Sharing for Microsoft Networks
Summary of Recommendations for File Sharing
Printing Protocols
Related Protocols
18. Remote Access to Hosts
Terminal Access (Telnet)
Remote Command Execution
Remote Graphical Interfaces
19. Real-Time Conferencing Services
Internet Relay Chat (IRC)
ICQ
talk
Multimedia Protocols
NetMeeting
Multicast and the Multicast Backbone (MBONE)
20. Naming and Directory Services
Domain Name System (DNS)
Network Information Service (NIS)
NetBIOS for TCP/IP Name Service and Windows Internet
Name Service
The Windows Browser
Lightweight Directory Access Protocol (LDAP)
Active Directory
Information Lookup Services
21. Authentication and Auditing Services
What Is Authentication?
Passwords
Authentication Mechanisms
Modular Authentication for Unix
Kerberos
NTLM Domains
Remote Authentication Dial-in User Service (RADIUS)
TACACS and Friends
Auth and identd
22. Administrative Services
System Management Protocols
Routing Protocols
Protocols for Booting and Boot-Time Configuration
ICMP and Network Diagnostics
Network Time Protocol (NTP)
File Synchronization
Mostly Harmless Protocols
23. Databases and Games
Databases
Games
24. Two Sample Firewalls
Screened Subnet Architecture
Merged Routers and Bastion Host Using General-Purpose Hardware
IV. Keeping Your Site Secure
25. Security Policies
Your Security Policy
Putting Together a Security Policy
Getting Strategic and Policy Decisions Made
What If You Can't Get a Security Policy?
26. Maintaining Firewalls
Housekeeping
Monitoring Your System
Keeping up to Date
How Long Does It Take?
When Should You Start Over?
27. Responding to Security Incidents
Responding to an Incident
What to Do After an Incident
Pursuing and Capturing the Intruder
Planning Your Response
Being Prepared
V. Appendixes
A. Resources
B. Tools
C. Cryptography
Index