What are the best practices for securing PHP pages from unauthorized external access?

To secure PHP pages from unauthorized external access, one of the best practices is to use server-side validation to check if the request is coming from an authorized source. This can be done by checking the IP address of the incoming request against a whitelist of approved IP addresses. 

// Check if the request is coming from an authorized IP address
$allowed_ips = array('192.168.1.1', '10.0.0.1');
$client_ip = $_SERVER['REMOTE_ADDR'];

if (!in_array($client_ip, $allowed_ips)) {
    header('HTTP/1.0 403 Forbidden');
    die('Unauthorized access');
}

// Proceed with the rest of the code if the request is authorized

Keywords

Authentication Authorization CSRF protection Input validation Secure coding practices

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