Building Telephony Systems with OpenSER Table of Contents

Table of Contents

• Preface

• Chapter 1: Introduction to SIP
• SIP Basics
• SIP Proxy in the Context of a VOIP Provider
• SIP Operation Theory
• SIP Registration Process
• Server Operating as a SIP Proxy
• Server Operating as a SIP Redirect
• Basic Messages
• SIP Dialog Flow
• SIP Transactions and Dialogs
• The RTP Protocol
• Codecs
• DTMF-Relay
• Real Time Control Protocol (RTCP)
• Session Description Protocol (SDP)
• The SIP Protocol and the OSI Model
• The VoIP Provider "Big Picture"
• SIP Proxy
• User, Administration, and Provisioning Portal
• PSTN Gateway
• Media Server
• Media Proxy or RTP Proxy for Nat Traversal
• RADIUS Accounting
• CDRTool Rating
• Monitoring Tools

• Where You Can Find More Information
• Summary

• Chapter 2: The SIP Express Router
• Where Are We?
• What is the SIP Express Router?
• What Software to Use, SER or OpenSER?
• Usage Scenarios
• OpenSER Architecture
• Core and Modules
• Sections of the File openser.cfg
• Sessions, Dialogs, and Transactions
• openser.cfg Message Processing
• SIP Proxy—Expected Behavior
• Stateful Operation
• Differences between Strict Routing and Loose Routing
• Understanding SIP and RTP
• Summary

• Chapter 3: OpenSER Installation
• Hardware Requirements
• Software Requirements
• Lab—Installing Linux for OpenSER
• Downloading and Installing OpenSER v1.2
• Lab—Running OpenSER at the Linux Boot
• OpenSER v1.2 Directory Structure
• Configuration Files (etc/openser)
• Modules (/lib/openser/modules)
• Binaries (/sbin)
• Log Files
• Startup Options
• Summary

• Chapter 4: OpenSER Standard Configuration
• Where Are We?
• Analyzing the Standard Configuration
• Using the Standard Configuration
• Routing Basics
• Transactions and Dialogs
• Initial and Sequential Requests
• Routing in a Context of a Transaction
• Routing in the Context of a Dialog
• Lab—Tracking a Complete Dialog
• Lab—Running Stateless
• Lab—Disabling record-route
• Summary

• Chapter 5: Adding Authentication with MySQL
• Where Are We?
• The AUTH_DB Module
• The REGISTER Authentication Sequence
• Register Sequence (Packets Captured by ngrep)
• Register Sequence Code Snippet
• The INVITE Authentication Sequence
• INVITE Sequence Packet Capture
• Digest Authentication
• WWW-Authenticate Response Header
• The Authorization Request Header
• QOP—Quality of Protection
• Installing MySQL Support
• openser.cfg File Analysis
• The Openserctl Shell Script
• Openserctl Resource File
• Openserctlrc File
• Using OpenSER with Authentication
• Enhancing the Script
• Managing Multiple Domains
• Alternative Routes
• The Functions check_to() and check_from()
• Using Aliases
• Handling CANCEL requests and retransmissions
• Full Script with All the Resources Above
• Lab—Enhancing the Security
• Lab—Using Aliases
• Summary

• Chapter 6: Building the User Portal with SerMyAdmin
• SerMyAdmin
• Lab—Installing SerMyAdmin
• Basic Tasks
• Registering a New User
• Approving a New User
• User Management
• Domain Management
• Interface Customization
• Summary

• Chapter 7: Connectivity to the PSTN
• Where Are We?
• Requests Sent to the Gateway
• Requests Coming From the Gateway
• openser.cfg Inspection
• Lab—Using Asterisk as a PSTN Gateway
• Asterisk Gateway (sip.conf)
• Cisco 2601 Gateway
• Using LCR (Least Cost Routes)
• The LCR Module
• Configuration Diagram
• VoIP Provider Dial Plan
• The LCR Table
• The Gateways Table
• The Gateway Groups Table
• Adding, Removing, and Showing LCR and Gateways
• Openserctl LCR-Related Commands.
• Notes:
• Examples:
• Lab—Using the LCR Feature
• lcr Gateway Groups
• lcr Gateways
• lcr Routes
• Securing re-INVITES
• Blacklists and "473/Filtered Destination" messages
• Summary

• Chapter 8: Call Forward and Voice Mail
• Call Forwarding
• Pseudo-Variables
• AVP (Attribute-Value Pair) Overview
• AVPOPS Module Loading and Parameters
• Implementing Blind Call Forwarding
• Lab—Implementing Blind Call Forwarding
• Implementing Call Forward on Busy or Unanswered
• Inspecting the Configuration File
• Lab—Testing the Call Forward Feature
• Summary

• Chapter 9: SIP NAT Traversal
• NAT Types
• Full Cone
• Restricted Cone
• Port Restricted Cone
• Symmetric
• NAT Firewall Table
• Solving the SIP NAT Traversal Challenge
• Implementing a Far-End NAT Solution
• RFC3581 and the force_rport() Function
• Solving the Traversal of RTP Packets
• Handling REGISTER Requests behind NAT
• Determining if the Client is behind NAT

• Handling INVITE Messages behind NAT
• Handling the Responses
• MediaProxy Installation and Configuration
• Installing MediaProxy

• openser.cfg Analysis
• Modules Loading
• Modules' Parameters
• Register Message Processing
• Invite Message Processing
• BYE and CANCEL Message Processing
• RE-INVITE Message Handling
• Reply Message Handling
• Routing Script

• Invite Diagram
• Packet Sequence

• Lab Using MediaProxy for NAT Traversal
• Implementing a Near-End NAT Solution
• Why STUN Does Not Work with Symmetric NAT Devices
• Comparing STUN with TURN (Media Relay Server)
• ALG—Application Layer Gateways
• ICE (Interactive Connection Establishment)
• Summary

• Chapter 10: OpenSER Accounting and Billing
• Objectives
• Where Are We?
• VoIP Provider Architecture
• Accounting Configuration
• LAB—Accounting using MySQL
• openser.cfg Analysis
• Accounting using RADIUS
• Installation of FreeRADIUS and CDRTool
• Packages and Dependencies
• Create and Configure the Database for the Radius server
• Configuration of the FreeRADIUS Server
• Configure the RADIUS Client (radiusclient-ng)
• Configure OpenSER
• Test the Configuration after Making a Call
• Using CDRTool for Rating
• LAB—CDRTool Installation
• LAB—Using CDRTool
• CDRTool Architecture
• How CDRTool Rates a Call
• Lab—Creating and Applying a Rating Plan
• Summary

• Chapter 11: Troubleshooting Tools
• Objectives
• Built-in Tools
• Packet Capture and Trace Tools
• TShark, Wireshark
• SipTrace
• Stress Testing Tools
• Sipsak
• SIPp
• Installing SIPp
• Stress Test—The SIP Signaling
• Stress Test—The RTP Signaling
• Testing MediaProxy
• Monitoring Tools
• Summary

• After Words
• What's New in Version 1.2.3
• Cancel Handling
• Blacklist is Disabled by Default
• Method Filtering
• Alias_DB
• Branch_route
• Migration from 1.2.2 to 1.2.3 and 1.3.1
• Migrating the Script from Chapter 10 to openser 1.3.1
• RTPProxy
• Lab—Installing RTPProxy
• Areas for Further Investigation
• Carrier Route
• Dialog
• SIP Session Timers
• SIP Peering
• TLS Transport Layer Security
• Development
• PERL
• WeSIP
• Common Mistakes
• Daemon Does Not Start
• Client Unable to Register
• Sending a Call to a Provider with Authentication
• Typos in the Configuration File
• The Last Tip
• Forum and Training
• Summary

• Index