How To Create A Firewall Module In PHP

Firewall module in PHP without using any specific framework:

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


$allowedIPs = [

$clientIP = $_SERVER['REMOTE_ADDR'];

if (!isAllowedIP($clientIP)) {

// Continue with your application logic...

function isAllowedIP($clientIP)
    global $allowedIPs;
    return in_array($clientIP, $allowedIPs);

In this example, the script checks if the client’s IP address is in the $allowedIPs array. If it’s not, a 403 Forbidden response is sent and the script execution is terminated. Otherwise, the script continues with your application logic.

Step 2: Include the Firewall Middleware Include the firewall.php script at the beginning of your PHP files or in a common entry point file. For example:


require_once 'firewall.php';

// Continue with the rest of your application code...

By including the script, it will be executed for every request, ensuring that the firewall rules are applied.

Step 3: Customize the Firewall Rules You can modify the $allowedIPs array in the firewall.php script 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 without using a specific framework. Depending on the complexity of your application and requirements, you may need to customize it further, such as handling different HTTP methods, integrating with a database of allowed IP addresses, or handling exceptions and error responses in a more structured manner.