Asterisk Hacking

by Brashars

• ISBN13: 9781597491518
• ISBN10: 1597491519
• Format: Paperback
• Copyright: 2007-06-29
• Publisher: Elsevier Science

Summary

Asterisk has taken the power of the open-source software movement and brought it to the land of telephony. Much like how open source has proven that users don't need to rely on commercial companies for software, Asterisk has proven that users don't need to rely on commercial telephone companies for telephone systems. Open-source software allows you to be free of vendor lock-in, save money on support, use open standards, and change the software to suit your unique problems if the need arises. Thanks to Asterisk and VoIP, it is possible to run a telephone company out of a basement, handling telephone calls for people within a neighborhood, a city, or a country. Doing this only a few years ago would have required buying a large building, setting up large racks of equipment, and taking out a second mortgage. But today, everyone is jumping on the Asterisk bandwagon: hobbyists, telephone companies, universities, and small businesses to name a few. But what exactly is Asterisk? And what can it do? Let's find out.

Table of Contents

What Is Asterisk and Why Do You Need It?	p. 1
Introduction	p. 2
What Is Asterisk?	p. 3
What Is a PBX?	p. 3
What Is VoIP?	p. 4
The History of Asterisk	p. 5
Asterisk Today	p. 6
What Can Asterisk Do for Me?	p. 7
Asterisk as a Private Branch Exchange	p. 7
Advantages over Traditional PBXes	p. 8
Features and Uses	p. 10
Asterisk as a VoIP Gateway	p. 12
The Possibilities of VoIP	p. 13
Asterisk as a New Dimension for Your Applications	p. 15
Who's Using Asterisk?	p. 16
Summary	p. 17
Solutions Fast Track	p. 18
Links to Sites	p. 19
Frequently Asked Questions	p. 20
Setting Up Asterisk	p. 21
Introduction	p. 22
Choosing Your Hardware	p. 22
Picking the Right Server	p. 22
Processor Speed	p. 23
RAM	p. 23
Storage Space	p. 23
Picking the Right Phones	p. 24
Soft Phones	p. 24
Hard Phones	p. 25
Configuring Your Network	p. 28
Installing Asterisk	p. 30
Using an Asterisk Live CD	p. 30
SLAST	p. 31
Installing Asterisk from a CD	p. 36
Getting trixbox	p. 36
Booting trixbox	p. 37
Configuring trixbox	p. 40
trixbox's Web Interface	p. 41
Installing Asterisk from Scratch	p. 45
The Four Horsemen	p. 46
Asterisk Dependencies	p. 46
Getting the Code	p. 47
Gentlemen, Start Your Compilers!	p. 47
Installing Asterisk with Binaries	p. 52
Installing Asterisk on Windows	p. 52
Getting Asterisk Win32	p. 53
Installing AsteriskWin32	p. 53
Starting AsteriskWin32	p. 57
Starting and Using Asterisk	p. 58
Starting Asterisk	p. 58
Restarting and Stopping Asterisk	p. 59
Updating Configuration Changes	p. 60
Checklist	p. 60
Summary	p. 61
Solutions Fast Track	p. 61
Links to Sites	p. 62
Frequently Asked Questions	p. 63
Configuring Asterisk	p. 65
Introduction	p. 66
Figuring Out the Files	p. 66
Configuring Your Dial Plan	p. 69
Contexts, Extensions, and Variables! Oh My!	p. 70
Contexts	p. 70
Extensions	p. 70
Variables	p. 73
Tying It All Together	p. 74
Configuring extensions.ael	p. 82
Using AEL to Write Your Extensions	p. 82
Configuring Your Connections	p. 85
Connections, Connections, Connections!	p. 85
Configuration File Conventions	p. 86
Configuration File Common Options	p. 87
Users, Peers, and Friends	p. 87
Allowing and Disallowing Codecs	p. 87
Including External Files	p. 88
Configuring SIP Connections	p. 89
General SIP Settings	p. 89
Connecting to an SIP Server	p. 91
Setting Up an SIP Server	p. 93
Configuring IAX2 Connections	p. 94
Connecting to an IAX2 Server	p. 94
Setting Up an IAX2 Server	p. 95
Configuring Zapata Connections	p. 96
Setting Up a Wireline Connection	p. 96
Configuring Voice Mail	p. 98
Configuring Voice-Mail Settings	p. 99
Configuring Mailboxes	p. 99
Leaving and Retrieving Messages	p. 100
Provisioning Users	p. 101
Decision Time	p. 102
Configuring Phone Connections	p. 102
Configuring Extensions	p. 102
Configuring Voice Mail	p. 103
Finishing Up	p. 103
Configuring Music on Hold, Queues, and Conferences	p. 103
Configuring Music on Hold	p. 103
Music on Hold Classes	p. 104
Music on Hold and MP3s	p. 105
Configuring Call Queues	p. 105
Setting Up a Call Queue	p. 105
Getting Fancy with Call Queues and Agents	p. 106
Configuring MeetMe	p. 108
It's All about Timing	p. 108
Setting Up a Conference	p. 109
Checklist	p. 109
Summary	p. 110
Solutions Fast Track	p. 111
Links to Sites	p. 113
Frequently Asked Questions	p. 113
Writing Applications with Asterisk	p. 115
Introduction	p. 116
Calling Programs from within the Dial Plan	p. 116
Calling External Applications from the Dial Plan	p. 116
Example: The World's Largest Caller ID Display	p. 117
Writing Programs within the Dial Plan	p. 120
Using the Asterisk Gateway Interface	p. 120
AGI Basics	p. 120
STDIN, STDOUT, and STDERR	p. 121
Commands and Return Codes	p. 121
A Simple Program	p. 123
Interacting with the Caller	p. 126
Input to the Script	p. 126
Output from the Script	p. 127
Setting Up Your Script to Run	p. 129
Using Third-Party AGI Libraries	p. 130
Asterisk::AGI	p. 130
A Simple Program, Simplified with Asterisk::AGI	p. 130
Example: IMAP by Phone	p. 131
phpAGI	p. 134
A Simple Program, Simplified with phpAGI	p. 134
Example: Server Checker	p. 135
Using Fast, Dead, and Extended AGIs	p. 138
FastAGI	p. 138
Setting Up a FastAGI Server with Asterisk::FastAGI	p. 138
DeadAGI	p. 140
EAGI	p. 141
Checklist	p. 141
Summary	p. 142
Solutions Fast Track	p. 142
Links to Sites	p. 144
Frequently Asked Questions	p. 145
Understanding and Taking Advantage of VoIP Protocols	p. 147
Introduction	p. 148
Your Voice to Data	p. 148
Making Your Voice Smaller	p. 149
Session Initiation Protocol	p. 150
Intra-Asterisk eXchange (IAX2)	p. 154
Getting in the Thick of IAX2	p. 155
Capturing the VoIP Data	p. 156
Using Wireshark	p. 156
Extracting the VoIP Data with Wireshark (Method #1)	p. 158
Extracting the VoIP Data with Wireshark (Method #2)	p. 162
Getting VoIP Data by ARP Poisoning	p. 165
Man in the Middle	p. 169
Using Ettercap to ARP Poison	p. 170
Summary	p. 179
Solutions Fast Track	p. 179
Frequently Asked Questions	p. 181
Asterisk Hardware Ninjutsu	p. 183
Introduction	p. 184
Serial	p. 184
Serial "One-Way" AGI	p. 184
Dual Serial Communications	p. 190
Motion	p. 196
The Idea behind the Code	p. 198
Modems	p. 203
Fun with Dialing	p. 206
War Dialing	p. 206
iWar with VoIP	p. 218
All Modems Are Not Alike	p. 220
Legalities and Tips	p. 220
What You Can Find	p. 221
Summary	p. 222
Solutions Fast Track	p. 222
Frequently Asked Questions	p. 224
Threats to VoIP Communications Systems	p. 225
Introduction	p. 226
Denial-of-Service or VoIP Service Disruption	p. 226
Call Hijacking and Interception	p. 233
ARP Spoofing	p. 236
H.323-Specific Attacks	p. 241
SIP-Specific Attacks	p. 242
Summary	p. 243
Index	p. 245
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