# VPN Implementation Fix - Summary

## Problem
Users connecting to ProtonVPN were experiencing:
1. **IP Leaks**: Real IP address visible instead of VPN IP
2. **DNS Leaks**: DNS queries going to ISP instead of VPN DNS servers
3. **No Traffic Routing**: VPN connected but traffic not going through tunnel

## Root Causes

### 1. DNS Script Issues
The DNS update script was incorrectly parsing OpenVPN's DNS environment variables:
```bash
# BEFORE (broken)
echo "nameserver ${foreign_option_1#*DNS }" > /etc/resolv.conf

# AFTER (fixed)
for opt in ${!foreign_option_*}; do
  if echo ${!opt} | grep -q "DNS"; then
    DNS_IP=$(echo ${!opt} | awk '{print $3}')
    echo "nameserver $DNS_IP" >> /etc/resolv.conf
  fi
done
```

### 2. Missing Kill Switch
No firewall rules to prevent traffic from leaking outside the VPN tunnel when connected.

### 3. Incomplete VPN Configuration
Missing critical OpenVPN directives:
- `block-outside-dns` - Prevents DNS leaks
- `redirect-gateway def1 bypass-dhcp` - Ensures all traffic routes through VPN
- No VPN connection verification

### 4. No Diagnostic Tools
No way to verify VPN was actually working or diagnose leak issues.

## Solutions Implemented

### 1. Fixed DNS Update Script (`Dockerfile`)
- Properly parse `foreign_option_*` environment variables
- Iterate through all DNS options from OpenVPN
- Fallback to ProtonVPN DNS (10.2.0.1) if needed
- Added logging for debugging

### 2. Added Kill Switch (`backend/routes/vpn.js`)
```javascript
// Firewall rules to block non-VPN traffic
iptables -A OUTPUT -o lo -j ACCEPT              // Allow loopback
iptables -A OUTPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
iptables -A OUTPUT -p udp --dport 53 -j ACCEPT // Allow DNS
iptables -A OUTPUT -o tun+ -j ACCEPT            // Allow VPN
// Implicit: Everything else blocked
```

### 3. Enhanced OpenVPN Configuration (`backend/routes/vpn.js`)
Added/improved:
```conf
dhcp-option DNS 10.2.0.1
dhcp-option DNS 10.2.0.2
block-outside-dns                     // NEW: Prevent DNS leaks
redirect-gateway def1 bypass-dhcp     // IMPROVED: Better routing
pull-filter ignore "dhcp-option DOMAIN"
pull-filter ignore "block-outside-dns"
pull-filter ignore route-ipv6         // NEW: Disable IPv6 leaks
```

### 4. VPN Verification (`backend/routes/vpn.js`)
After connection, verify:
- Get public IP and compare
- Check DNS configuration
- Log connection details

### 5. Diagnostic Tools

#### New File: `backend/utils/vpnDiagnostics.js`
Comprehensive VPN diagnostics class:
- `getPublicIP()` - Get current public IP
- `getIPInfo()` - Get location, ISP, etc.
- `getDNSServers()` - Check current DNS
- `checkVPNInterface()` - Verify tun0 exists
- `getRoutingTable()` - Check traffic routing
- `checkDNSLeaks()` - Detect DNS leaks
- `runFullDiagnostics()` - Complete analysis

#### New API Endpoint: `/api/vpn/diagnostics`
Returns comprehensive diagnostics:
```json
{
  "publicIP": "X.X.X.X",
  "ipInfo": { "country": "US", "org": "ProtonVPN" },
  "dnsServers": ["10.2.0.1", "10.2.0.2"],
  "vpnInterface": { "exists": true },
  "routingTable": ["default via ... dev tun0"],
  "dnsLeakCheck": { "potentialLeak": false },
  "summary": {
    "vpnActive": true,
    "ipLeak": false,
    "dnsLeak": false,
    "issues": []
  }
}
```

### 6. Enhanced Frontend (`frontend/src/components/VPNSettings.jsx`)
Added "Check IP" button that displays:
- Current public IP
- Location (city, country)
- ISP/Organization
- DNS servers in use
- VPN interface status
- Warning if interface not active

### 7. Documentation
Created comprehensive troubleshooting guide: `docs/VPN_TROUBLESHOOTING.md`

## Files Modified

1. **Dockerfile**
   - Fixed DNS update script to properly parse OpenVPN variables
   - Added better logging

2. **backend/routes/vpn.js**
   - Added kill switch (firewall rules)
   - Enhanced OpenVPN configuration
   - Added VPN verification after connect
   - Cleanup firewall on disconnect
   - Improved status and check-ip endpoints
   - Added diagnostics endpoint
   - Import VPNDiagnostics utility

3. **backend/utils/vpnDiagnostics.js** *(NEW)*
   - Comprehensive VPN diagnostic tools
   - IP/DNS leak detection
   - Interface and routing verification

4. **frontend/src/components/VPNSettings.jsx**
   - Added "Check IP" button
   - Display connection details panel
   - Show IP, location, DNS, interface status
   - Warning alerts for issues

5. **docs/VPN_TROUBLESHOOTING.md** *(NEW)*
   - Complete troubleshooting guide
   - Common issues and solutions
   - Testing procedures
   - Architecture explanation

## How to Use

### 1. Rebuild Container
```bash
docker-compose down
docker-compose build
docker-compose up -d
```

### 2. Connect to VPN
1. Go to Settings > VPN
2. Enter ProtonVPN credentials
3. Click "Connect"
4. Wait for "VPN Connected" message

### 3. Verify Connection
Click "Check IP" button and verify:
- ✓ Public IP is different from your real IP
- ✓ Location matches VPN country
- ✓ ISP shows ProtonVPN or VPN-related
- ✓ DNS servers are `10.2.0.1`, `10.2.0.2`
- ✓ VPN Interface shows "Active"

### 4. Run Diagnostics (Optional)
```bash
curl -H "Authorization: Bearer YOUR_TOKEN" \
  http://localhost:12345/api/vpn/diagnostics
```

## Testing Checklist

- [ ] Container rebuilds successfully
- [ ] VPN connects without errors
- [ ] Check IP shows VPN IP (not real IP)
- [ ] Location matches selected country
- [ ] DNS servers are ProtonVPN DNS
- [ ] VPN interface (tun0) is active
- [ ] Can browse internet while connected
- [ ] Streams work through VPN
- [ ] Disconnect works properly
- [ ] Firewall rules cleaned up on disconnect

## Security Improvements

1. **Kill Switch**: Traffic blocked if VPN drops
2. **DNS Security**: Forced to VPN DNS only
3. **No IPv6 Leaks**: IPv6 filtered out
4. **Proper Routing**: All traffic through tunnel
5. **Verification**: Connection verified after connect

## Performance Considerations

- Free tier VPN has speed limits
- Kill switch adds minimal overhead
- DNS lookup uses VPN DNS (may be slower)
- Firewall rules are lightweight

## Troubleshooting

If still experiencing issues:

1. **Check logs**: `docker logs streamflow`
2. **Run diagnostics**: Use `/api/vpn/diagnostics` endpoint
3. **Verify credentials**: Ensure ProtonVPN login is correct
4. **Try different server**: Switch countries
5. **Check Docker**: Ensure `NET_ADMIN` and `NET_RAW` capabilities
6. **Rebuild**: `docker-compose build --no-cache`

## Next Steps (Optional Enhancements)

1. **Auto-reconnect**: Reconnect VPN if connection drops
2. **Multiple servers**: Load balance across servers
3. **Connection testing**: Periodic leak checks
4. **WireGuard support**: Alternative to OpenVPN
5. **Split tunneling**: Route only specific traffic through VPN
6. **IPv6 support**: Proper IPv6 over VPN

## Notes

- VPN connection is per-user (not container-wide)
- Each user can connect to different VPN servers
- Free tier has bandwidth/speed limitations
- Some services may detect/block VPN traffic
- Credentials stored encrypted in database
