node-sbc/README.md

NexusVoice SBC - Drachtio Migration

This directory contains the Drachtio-based implementation of the NexusVoice SIP Border Controller, migrated from the original Kamailio configuration.

Overview

The Drachtio implementation provides equivalent functionality to the Kamailio SBC configuration:

• SIP Proxy and Registrar: User registration and location management
• Security Features: User-Agent filtering, SIP validation, request sanitization
• Call Routing: Local user lookup, special number routing, external trunk integration
• Media Handling: RTP proxy integration for media relay
• Logging: Comprehensive SIP traffic logging

Directory Structure

drachtio-migration/
├── config/
│   └── default.json              # Main configuration file
├── middleware/
│   ├── validation.js            # Request validation middleware
│   ├── userAgentFilter.js       # User-Agent filtering middleware
│   └── requestProcessor.js      # Main request processing pipeline
├── routes/
│   ├── registration.js          # SIP REGISTER handling
│   ├── invite.js               # SIP INVITE handling
│   └── indialog.js             # In-dialog request handling
├── utils/
│   └── logger.js               # Logging utility
├── server.js                   # Main server application
├── package.json               # Node.js dependencies
└── README.md                  # This file

Installation and Setup

Prerequisites

• Node.js 14.0 or higher
• Drachtio server installed and running
• RTP proxy server (optional, for media handling)

Installation

1. Navigate to the migration directory:

cd drachtio-migration

2. Install dependencies:

npm install

3. Configure your settings in config/default.json:
   • SIP listening parameters
   • RTP proxy configuration
   • Asterisk server addresses
   • Security settings

Configuration

Key configuration sections:

{
  "sip": {
    "host": "0.0.0.0",
    "port": 5060,
    "transport": "udp"
  },
  "rtpProxy": {
    "enabled": true,
    "host": "rtpproxy",
    "port": 7722
  },
  "security": {
    "enableUAFilter": true,
    "blockedUserAgents": [...],
    "allowedUserAgents": [...]
  }
}

Running the Server

Development mode:

npm run dev

Production mode:

npm start

Migration Mapping

Kamailio to Drachtio Equivalents

Kamailio Component	Drachtio Implementation
request_route	RequestProcessor.middleware()
route[REQINIT]	RequestValidator.middleware()
route[UA_FILTER]	UserAgentFilter.middleware()
route[REGISTRAR]	RegistrationHandler.handleRegister()
route[INCOMING_INVITE]	InviteHandler.handleInvite()
route[WITHINDLG]	InDialogHandler.handleInDialog()
usrloc module	RegistrationHandler.registry (in-memory Map)
rtpproxy module	RTP proxy integration (placeholder)
dispatcher module	Round-robin Asterisk server selection

Key Differences

1. Configuration: JSON-based instead of Kamailio script syntax
2. Language: JavaScript/Node.js instead of Kamailio configuration language
3. Architecture: Middleware pattern instead of procedural routes
4. Persistence: In-memory registry instead of database-backed usrloc
5. Logging: Winston-based logging instead of xlog

Features Implemented

✅ Request Processing Pipeline

• Max-Forwards validation
• SIP message sanity checks
• Method-specific routing
• Enhanced logging
• Retransmission handling

✅ Security Features

• User-Agent filtering with allow/block lists
• Empty User-Agent blocking
• Attack tool pattern detection
• Request validation and sanitization

✅ Registration System

• SIP REGISTER handling
• In-memory user registry
• Registration expiry management
• Automatic cleanup of expired registrations

✅ Call Routing

• Local user lookup
• Special number routing (3179, 8000, *600, 888)
• Asterisk server integration
• Round-robin load balancing

✅ In-Dialog Handling

• BYE request processing
• ACK handling
• Route header processing
• Media teardown handling

Testing

The migration is ready for functional testing. Key test scenarios:

1. Registration Tests

   • User registration and authentication
   • Registration expiry and cleanup
   • Unregistration handling

2. Call Routing Tests

   • Local user calls
   • Special number calls
   • External trunk routing

3. Security Tests

   • User-Agent filtering
   • Request validation
   • Attack prevention

4. Media Tests

   • RTP proxy integration
   • SDP processing

Next Steps

🔄 In Progress

• RTP proxy integration for media handling
• SDP processing and modification
• Media relay configuration

⏳ Planned Features

• Redis integration for multi-instance support
• Enhanced logging and monitoring
• API endpoints for management
• Performance optimization
• Load testing and validation

Troubleshooting

Common Issues

1. Port already in use: Ensure no other SIP server is running on port 5060
2. Drachtio connection failed: Verify drachtio server is running and accessible
3. Registration fails: Check From header format and contact headers
4. Call routing fails: Verify user registration and Asterisk server connectivity

Logs

Check the logs directory for detailed information:

tail -f logs/sbc.log

Contributing

This migration maintains the same functionality as the original Kamailio configuration while leveraging Drachtio's modern JavaScript-based architecture. All existing features should work equivalently.