Firewalls, Network Address Translation (NAT), network logging and accounting are all provided by Linux's Netfilter system, also known by the name of the command used to administer it, iptables. The iptables interface is the most sophisticated ever offered on Linux and makes Linux an extremely flexible system for any kind of network filtering you might do. Large sets of filtering rules can be grouped in ways that makes it easy to test them and turn them on and off. Do you watch for all types of ICMP traffic--some of them quite dangerous? Can you take advantage of stateful filtering to simplify the management of TCP connections? Would you like to track how much traffic of various types you get? This pocket reference will help you at those critical moments when someone asks you to open or close a port in a hurry, either to enable some important traffic or to block an attack. The book will keep the subtle syntax straight and help you remember all the values you have to enter in order to be as secure as possible. The book has an introductory section that describes applications,followed by a reference/encyclopaedic section with all the matches and targets arranged alphabetically.

Table of Contents

Introduction

An Example Command

Concepts

Applications

Configuring iptables

Connection Tracking

Accounting

Network Address Translation (NAT)

Source NAT and Masquerading

Destination NAT

Transparent Proxying

Load Distribution and Balancing

Stateless and Stateful Firewalls

Tools of the Trade

iptables Command Reference

Getting help

The iptables Subcommands

iptables Matches and Targets

Utility Command Reference

iptables-restore

iptables-save

About the Author

Gregor N. Purdy is a consultant, author, trainer, and lecturer on large-scale decision support system requirements, design, and implementation. He is also the author of various Perl modules and the Perl Shell. He uses CVS to manage his personal projects and those of his clients. He is also a contributor to the Comprehensive Perl Archive Network (CPAN) and to the ongoing development of the new Perl 6 virtual machine, Parrot.