Book Image

Asterisk 1.6

Book Image

Asterisk 1.6

Overview of this book

Asterisk is a powerful and flexible open source framework for building feature-rich telephony systems. As a Private Branch Exchange (PBX) which connects one or more telephones, and usually connects to one or more telephone lines, Asterisk offers very advanced features, including extension-to-extension calls, queues, ring groups, line trunking, call distribution, call detail rerecords, and call recording. This book will show you how to build a telephony system for your home or business using this open source application. 'Asterisk 1.6' takes you step-by-step through the process of installing and configuring Asterisk. It covers everything from establishing your deployment plan to creating a fully functional PBX solution. Through this book you will learn how to connect employees from all over the world as well as streamline your callers through Auto Attendants (IVR) and Ring Groups.This book is all you need to understand and use Asterisk to build the telephony system that meets your need. You will learn how to use the many features that Asterisk provides you with. It presents example configurations for using Asterisk in three different scenarios: for small and home offices, small businesses, and Hosted PBX. Over the course of ten chapters, this book introduces you to topics as diverse as Public Switched Telephony Network (PSTN), Voice over IP Connections (SIP / IAX), DAHDI, libpri, through to advanced call distribution, automated attendants, FreePBX, and asterCRM. With an engaging style and excellent way of presenting information, this book makes a complicated subject very easy to understand.
Table of Contents (15 chapters)
Asterisk 1.6
Credits
About the Authors
About the Reviewer
Preface

Network security for Asterisk


As many of the protocols Asterisk supports are used over a TCP/IP network, we need an understanding of how to control and firewall these correctly in order to ensure that we only let the necessary traffic pass through.

Our firewall will most likely be on a box separate from our Asterisk installation and placed at the network perimeter (we may also have a host-based firewall to which different rules may apply). In order to define the required rules, I won't detail how to configure a specific firewall product, but provide the details necessary to configure any device we have protecting our Asterisk installation.

These rules would apply to any device, be it iptables on a Linux machine, a commercial firewall such as Microsoft ISA server or checkpoint, PIX, and so on. The product in use isn't the main issue, the protocol rules that are required are. We can then take these generic rules and apply them to any firewall device we decide to install.

Firewalling the Asterisk...