How To Create A Firewall Module In Node.Js

Firewall module in Node.js using the Express framework:

Step 1: Create a Firewall Middleware Create a middleware function called firewall that will intercept incoming requests and apply the firewall rules. Here’s an example:

					// firewall.js

const allowedIPs = ['', ''];

function firewall(req, res, next) {
  const clientIP = req.ip;

  if (!isAllowedIP(clientIP)) {
    return res.sendStatus(403);


function isAllowedIP(clientIP) {
  return allowedIPs.includes(clientIP);

module.exports = firewall;

In this example, the firewall middleware function checks if the client’s IP address is in the allowedIPs array. If it’s not, a 403 Forbidden response is sent. Otherwise, the next() function is called to proceed to the next middleware or route handler.

Step 2: Use the Firewall Middleware in your Express Application In your Express application, require the firewall middleware and use it to protect the desired routes. Here’s an example:

					// app.js

const express = require('express');
const firewall = require('./firewall');

const app = express();


app.get('/', (req, res) => {
  res.send('Hello, world!');

app.listen(3000, () => {
  console.log('Server is running on port 3000');

In this example, the firewall middleware is applied to all routes by using app.use(firewall). You can customize the middleware usage according to your specific needs.

Step 3: Customize the Firewall Rules You can modify the allowedIPs array in the firewall.js file to include or exclude IP addresses based on your firewall rules. Add or remove IP addresses as needed.

Please note that this is a basic example of a firewall module, and you may need to customize it further based on your specific requirements, such as adding more complex rules, integrating with a database of allowed IP addresses, or handling exceptions and error responses.