Virtual hosting with multiple user IDs is possible to increase Apache security with mod_proxy.
In this article, Nick Maynard outlines a method for you to improve the security of a LAMP setup by using Apache's mod_proxy module. This article is specific to Linux; however, you can also apply some of the principles to other operating systems.
One challenge that faces LAMP administrators is that of providing all the features of a full PHP installation while ensuring a secure environment for all users of the system. Use of PHP's safe mode is one technique for meeting this goal, but it can also unduly limit users, and some PHP applications simply don't function with this facility enabled.
In this article, you'll explore a method that improves the security of your LAMP installation by using the mod_proxy module and multiple back-end servers. I'll discuss the merits and drawbacks of such an approach, and you'll see an example configuration of a working setup.