prevent customer to upload hacking tools!

I 'm looking for a good solution to prevent one of my customer to upload backdoors or some back php tools to hack other customer website ... !!!
I want to know i anyone have a good experience on this topic.

I think installing one anti virus agent on web server is good solution but do'nt know about open source solutions !!!


TNX,

 

The first thing I'd do is enable PHP Safe Mode for this web site.

 

good, but many cms software need safe mode to be off !!!
what should i do with this ?!!!

 

something like this:

http://www.howtoforge.com/forums/showpost.php?p=170555&postcount=8

this is proven to work ok at least when it comes to Joomla.