Thank you, I believe Red Hat Enterprise Linux comes with Squid. Howver, I read the page at squidguard.org (Thanks for the link) It looks like what I wanted, but it was like it was written in another language
. I don't know all this stuff, I would prefer to work with preconfigured software, so I (my company) is willing to pay for the service.
However, I will consider using squidguard and look into this solution further.
Thanks Tinkster and pxlpluker for your help