301 redirect 177
Referrer Masking
Redirection services can hide the referrer by placing an intermediate page between the page the link is on and its
destination. Although these are conceptually similar to other URL redirection services, they serve a different
purpose, and they rarely attempt to shorten or obfuscate the destination URL (as their only intended side-effect is to
hide referrer information and provide a clear gateway between other websites.)
This type of redirection is often used to prevent potentially-malicious links from gaining information using the
referrer, for example a session ID in the query string. Many large community websites use link redirection on
external links to lessen the chance of an exploit that could be used to steal account information, as well as make it
clear when a user is leaving a service, to lessen the chance of effective phishing.
Here is a simplistic example of such a service, written in PHP.<?php$url = htmlspecialchars($_GET['url']);header( 'Refresh: 0; url=http://'.$url );?>
<!-- Fallback using meta refresh. --><html><head><title>Redirecting...</title><meta http-equiv="refresh" content="0;url=http://<?php echo $url; ?>"></head><body>Attempting to redirect to <a href="http://<?php echo $url; ?>">http://<?php echo $url; ?></a>.</body></html>