How to redirect FORWARD proxy users to webpage using mod_proxy - apache

Question

I have searched quite a lot for a solution and most answers pertain to either proxypass (reverse proxy) or are not relevant.

End users' web browsers are configured to use the Apache proxy server.

I want to redirect all users to an individual web page (on the same server if possible).

Mod_rewrite does not work as it is only triggered when a user tried to visit the proxy server. I want to redirect users trying to access external sites.

The current configuration is simple:

/var/httpd/conf.d/proxy.conf:

<VirtualHost *:*> ProxyRequests On ProxyVia On <Proxy *> Order deny,allow Deny from all Allow from 172.0.0.0/21 </Proxy> </VirtualHost> 

I was thinking of blocking all requests and then setting a custom error page but cannot find any examples of this working.

Answer 1

I haven't tried output filters with forward proxying, but it works with reverse proxying, so you might want to give the following a try:

#add this outside of any VirtualHost tags ExtFilterDefine proxiedcontentfilter mode=output cmd="/usr/bin/php /var/www/proxyfilter.php" #add this in your VirtualHost tag SetOutputFilter proxiedcontentfilter In proxyfilter.php have some code like the following: #!/usr/bin/php <?php $html = file_get_contents('php://stdin'); #update this if-condition to match any non-internal hostnames if ($_SERVER['HTTP_HOST'] != 'www.example.com') { header('Location: http://localserver/message_to_display.html'); $html = ''; } file_put_contents('php://stdout', $html);