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Detect VPN & Proxy IPs with Node.js

Protect your Node.js app from anonymous and suspicious traffic

This tutorial shows you how to detect VPN, proxy, TOR, and bot IP addresses in Node.js using the built-in fetch API (Node.js 18+) and the Focsec API.

You'll also learn how to implement VPN detection as Express.js middleware to protect sensitive routes.

1

Check an IP for VPN or proxy

Make an API request to detect VPN and proxy IPs.

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javascript 
const API_KEY = 'your-api-key-here';

async function checkIP(ipAddress) {
  const response = await fetch(
    `https://api.focsec.com/v1/ip/${ipAddress}`,
    {
      headers: {
        'Authorization': API_KEY
      }
    }
  );

  return response.json();
}

// Usage
const result = await checkIP('82.40.11.200');
console.log(result);

API Response

The response includes boolean flags for each threat type and geolocation data:

Response 
{
  "ip": "82.40.11.200",
  "is_vpn": false,
  "is_proxy": false,
  "is_bot": false,
  "is_tor": false,
  "is_datacenter": false,
  "city": "London",
  "country": "United Kingdom",
  "iso_code": "gb",
  "is_in_european_union": false,
  "flag": "šŸ‡¬šŸ‡§",
  "autonomous_system_number": 5089,
  "autonomous_system_organization": "Virgin Media Limited"
}
2

Detect suspicious IPs

Create a helper function to flag VPN, proxy, TOR, or bot connections:

javascript 
function isSuspicious(data) {
  return data.is_vpn || data.is_proxy || data.is_tor || data.is_bot || data.is_datacenter;
}

async function checkAndFlag(ipAddress) {
  const result = await checkIP(ipAddress);

  if (isSuspicious(result)) {
    console.log(`VPN/Proxy detected: ${result.ip}`);
    console.log(`VPN: ${result.is_vpn}, Proxy: ${result.is_proxy}`);
    console.log(`TOR: ${result.is_tor}, Bot: ${result.is_bot}`);
  } else {
    console.log(`Clean IP: ${result.ip}`);
  }

  return result;
}
3

Express.js middleware

Protect checkout and other sensitive routes by blocking VPN and proxy users:

javascript 
import express from 'express';

const app = express();
const API_KEY = process.env.FOCSEC_API_KEY;

async function checkIP(ip) {
  const response = await fetch(
    `https://api.focsec.com/v1/ip/${ip}`,
    { headers: { 'Authorization': API_KEY } }
  );
  return response.json();
}

function isSuspicious(data) {
  return data.is_vpn || data.is_proxy || data.is_tor || data.is_bot || data.is_datacenter;
}

// Middleware to detect VPN/proxy users
async function vpnDetectionMiddleware(req, res, next) {
  const clientIP = req.ip || req.connection.remoteAddress;

  try {
    const result = await checkIP(clientIP);
    req.focsec = result;

    // Block VPNs and proxies on sensitive routes
    if (req.path.startsWith('/checkout')) {
      if (isSuspicious(result)) {
        return res.status(403).json({
          error: 'VPN/Proxy detected. Please disable to continue.'
        });
      }
    }

    next();
  } catch (error) {
    // Don't block on API errors
    console.error('VPN check failed:', error.message);
    next();
  }
}

app.use(vpnDetectionMiddleware);

app.get('/checkout', (req, res) => {
  res.json({ message: 'Checkout page', ip_info: req.focsec });
});

app.listen(3000);

Next steps

You've successfully added VPN detection to your Node.js app. See the API Reference for additional response fields and options.

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