There's been users surfing "porn" sites and I know these are sites that aren't good. But also, I dont want these users to be on these sites. How can I modify the PHProxy, proxy script, or CGI proxy script, so that when a certain domain is typed, it instead redirects to another innocent site, like google? I'll give you a free word clouds script if someone can help me one on one!
Perhaps run some regex matching on the url looking for tell-tale words (teen, pron, etc.) and then redirect to a standard page while placing the user's IP in a deny file. regex engine has some overhead though.
Are you sure proxies are really your thing? Sad as it may be, porn is what maybe 50% (if not more) of people use proxies for, and a proxy is suppose to be about allowing sites to be viewed where they cant be otherwise, after all. BTW why porn as "porn", porn is just porn, theres nothing dubious in the description