The ProDevTips.com site has a tutorial posted showing you how to proxy requests with PHP on Ubuntu using Apache 2.4 and PHP version 5.4 or later.

I’ve just had to evade a Russian block of one of my employer’s sites, let’s call it CasinoX. Presumably they had blocked both www.casinox.com and www.casinox.com’s IP address (which is a Cloud Flare IP btw).

Simply pointing ru.casinox.com to the real IP address of www.casinox.com’s server was a not a viable solution though as that would expose the real IP publicly which is a no-go in the online casino business as it is basically an invitation to be DDoS’ed.

The solution they came up with was to set up a server that operates as a proxy and sends all traffic to the actual web server, save the assets (images, Javascript files, etc). They include the changes you'll need to the .htaccess configuration on the proxy server to forward the requests. Then they show the updated version of your virtual hosts configuration to match these changes. From there the rest of the handling lives in PHP. They include the code for the index.php proxy handling, a Proxy class that makes curl requests to the actual web server and an ip_in_range function to get the actual IP of the user/client making the request.