How Can I Prevent Direct Access to Included PHP Files?

Preventing Direct File Access in PHP

In the world of web development, it's essential to control access to sensitive files, especially those intended solely for inclusion within other scripts. A common issue arises when such files can be accessed directly through the URL, leading to potential security vulnerabilities.

To address this concern, PHP offers a straightforward solution that allows you to restrict direct access to included files. By implementing a simple conditional check, you can deter unauthorized attempts to execute those files directly.

To effectively implement this protection, follow these steps:

1. Check Referrer Source

Open the PHP file that you intend to use exclusively as an include. Add the following code to the beginning of the file:

if (!isset($_SERVER['HTTP_REFERER'])) {
    die('Direct access not permitted');
}

$current_url = $_SERVER['HTTP_REFERER'];
$allowed_url = 'https://example.com/page_that_includes_this_file.php';

if ($current_url != $allowed_url) {
    die('Direct access not permitted');
}

2. Define a Constant

In the PHP file that includes the protected file, add the following code at the beginning:

define('MY_CONSTANT', TRUE);

Explanation:

The first piece of code checks if the request came from the expected referring URL (in this case, the page that should include the file). If the referrer is not set or does not match the allowed URL, it generates an error message.

The next part of the code defines a constant named "MY_CONSTANT" in the include file. On the pages that include it, you define this constant to TRUE, ensuring that the page can access the file legitimately.

By implementing this mechanism, you can effectively prevent direct access to the include file, ensuring its integrity and preventing unauthorized execution.

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