Express req.ip Property

Posted in Express Tutorial

Updated on Feb 18, 2024

By Mari Selvan

👁️ 43 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

When building web applications with Express.js, it's often crucial to know the IP address of the client making a request.

The req.ip property in Express provides a straightforward way to access this information.

In this guide, we'll explore the syntax, usage, and practical examples of the req.ip property, helping you gain insights into the IP addresses of your clients.

💡 Syntax

Accessing the client's IP address using req.ip is as simple as:

syntax.js

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const clientIP = req.ip;

❓ How req.ip Works

The req.ip property in Express.js retrieves the IP address of the client making the request. It considers various factors, including the X-Forwarded-For header, which may contain a comma-separated list of IP addresses representing the client and any intermediate proxies.

example.js

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app.get('/client-ip', (req, res) => {
  const clientIP = req.ip;
  res.send(`Client IP Address: ${clientIP}`);
});

In this example, the /client-ip route handler uses req.ip to retrieve the client's IP address and sends it as a response.

📚 Use Cases

Logging Client IP Addresses:

Use req.ip to log client IP addresses for requests, aiding in debugging and monitoring.
example.js
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```
app.use((req, res, next) => {
  const clientIP = req.ip;
  console.log(`Request from IP: ${clientIP}`);
  next();
});
```

IP-Based Authentication:

Leverage req.ip for IP-based authentication, allowing or denying access based on client IP addresses.

example.js

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app.use('/admin', (req, res, next) => {
  const allowedIPs = ['192.168.1.1', '10.0.0.1'];
  const clientIP = req.ip;

  if (allowedIPs.includes(clientIP)) {
    // Allow access to admin routes
    next();
  } else {
    res.status(403).send('Forbidden: Access denied from your IP address.');
  }
});

🏆 Best Practices

Trust Proxy Setting:

When using a reverse proxy, set the trust proxy setting to instruct Express to trust the X-Forwarded-For header and correctly determine the client's IP address.
example.js
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```
// Enable trust for the X-Forwarded-For header
app.set('trust proxy', true);
```
Handle Multiple IP Addresses:

Be aware that req.ip may return a comma-separated list of IP addresses when there are multiple proxies involved. Consider extracting the primary client IP if needed.
example.js
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```
// Extract the primary IP address from the X-Forwarded-For header
const clientIP = req.ip.split(',')[0];
```

🎉 Conclusion

Understanding and utilizing the req.ip property in Express.js allows you to gain insights into the IP addresses of clients making requests to your server. Whether for logging, authentication, or other use cases, req.ip proves to be a valuable tool in your Express.js toolkit.

Now, equipped with knowledge about req.ip, go ahead and enhance your Express.js projects with accurate client IP address handling!