Modem Connection Rotator

A simple HTTP service for Raspberry Pi that allows you to rotate modem connections via REST API calls.

Features

• HTTP API: Simple REST endpoints to control modem connections
• Connection Status: Real-time monitoring of connection state
• Automatic Rotation: Disconnect and reconnect modem with configurable delays
• Multiple Methods: Supports NetworkManager, direct interface control, and dial-up processes
• Logging: Comprehensive logging to file and console
• Systemd Integration: Runs as a system service with auto-restart

Quick Start

1. Transfer files to your Raspberry Pi:

   scp -r * pi@your-pi-ip:/home/pi/rotator/

2. Run setup script on Pi:

   cd /home/pi/rotator
   chmod +x setup.sh
   ./setup.sh

3. Test the service:

   # Check connection status
   curl http://localhost:8080/status
   
   # Rotate connection
   curl -X POST http://localhost:8080/rotate

API Endpoints

GET /

Service information and available endpoints

GET /status

Returns current connection status:

{
  "interface": "wwan0",
  "interface_up": true,
  "ip_address": "192.168.1.100",
  "internet_connected": true,
  "last_rotation": "2024-01-01T12:00:00",
  "rotation_count": 5
}

GET /health

Simple health check endpoint

POST /rotate

Rotates the modem connection (disconnect + reconnect):

{
  "success": true,
  "message": "Connection rotated successfully",
  "initial_status": {...},
  "final_status": {...},
  "rotation_time": "2024-01-01T12:05:00",
  "total_rotations": 6
}

Configuration

Edit config.json to customize settings:

{
  "port": 8080,
  "interface": "wwan0",
  "disconnect_delay": 5,
  "reconnect_timeout": 30,
  "log_level": "INFO"
}

• port: HTTP server port
• interface: Network interface name (common: wwan0, ppp0, usb0)
• disconnect_delay: Seconds to wait between disconnect and reconnect
• reconnect_timeout: Maximum seconds to wait for reconnection
• log_level: Logging level (DEBUG, INFO, WARNING, ERROR)

Finding Your Interface

To find your modem's interface name:

# List all network interfaces
ip link show

# Check for cellular/modem interfaces
ip link show | grep -E "(wwan|ppp|usb)"

# Check NetworkManager devices
nmcli device status

Common interface names:

• wwan0 - USB cellular modems
• ppp0 - Dial-up connections
• usb0 - USB tethering
• eth1 - Some USB ethernet adapters

Service Management

# View service status
sudo systemctl status rotator.service

# Start/stop/restart
sudo systemctl start rotator.service
sudo systemctl stop rotator.service
sudo systemctl restart rotator.service

# View logs
sudo journalctl -u rotator.service -f

# Disable auto-start
sudo systemctl disable rotator.service

Remote Usage

To access from other devices on your network:

1. Find Pi's IP address:

   ip addr show | grep inet

2. Test from remote device:

   curl http://PI_IP_ADDRESS:8080/status
   curl -X POST http://PI_IP_ADDRESS:8080/rotate

3. Open firewall if needed:

   sudo ufw allow 8080

Troubleshooting

Permission Issues

The service needs sudo access for network commands. If you get permission errors:

# Check sudoers configuration
sudo visudo

# Should include something like:
pi ALL=(ALL) NOPASSWD: /sbin/ip, /usr/bin/nmcli, /sbin/dhclient, /usr/bin/killall

Interface Not Found

If the service can't find your modem interface:

1. Check available interfaces: ip link show
2. Update interface in config.json
3. Restart service: sudo systemctl restart rotator.service

Connection Issues

If rotation fails:

1. Check logs: sudo journalctl -u rotator.service -n 50
2. Test manually: sudo nmcli device disconnect wwan0
3. Verify modem is detected: lsusb | grep -i modem

Service Won't Start

Check the logs for errors:

sudo journalctl -u rotator.service -n 20

Common issues:

• Python3 not installed: sudo apt install python3
• Port already in use: Change port in config.json
• File permissions: chmod +x /home/pi/rotator/rotator.py

Examples

Bash Script to Rotate and Wait

#!/bin/bash
echo "Rotating connection..."
curl -X POST http://localhost:8080/rotate
echo "Waiting for new IP..."
sleep 10
curl http://localhost:8080/status | grep ip_address

Python Client

import requests
import time

# Rotate connection
response = requests.post('http://PI_IP:8080/rotate')
if response.json()['success']:
    print("Connection rotated successfully")
    
    # Wait and check new status
    time.sleep(5)
    status = requests.get('http://PI_IP:8080/status').json()
    print(f"New IP: {status['ip_address']}")

Cron Job for Periodic Rotation

# Add to crontab (crontab -e)
# Rotate every hour
0 * * * * curl -X POST http://localhost:8080/rotate >/dev/null 2>&1

License

MIT License - feel free to modify and distribute.