How can PHP developers ensure that a certain page can only be accessed through a specific referring page, such as Index.php?

To ensure that a certain page can only be accessed through a specific referring page, such as Index.php, PHP developers can check the referring page in the HTTP headers of the request. If the referring page is not Index.php, the access can be denied by redirecting the user back to the referring page or displaying an error message. 

<?php
$referring_page = $_SERVER['HTTP_REFERER'];

if($referring_page != "http://example.com/Index.php") {
    header("Location: http://example.com/Index.php");
    exit();
}
?>

Keywords

PHP Referring page Access control HTTP_REFERER Redirect

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