web filtering
 

We are looking for a suitable open source web filter solution or commercial with reasonable price. Do anyone have any idea of the best filtering solution in the market for a medium size ISP with approx. 1000 customers not including the number of PC's they are using. The filtering should not affect the internet speed.

Are you wanting to filter just which sites are visited? Or which IP addresses are visited? Or do you want to filter based on what URL is accessed? Or by the literal content of a site? Do you want this filtering to be host based at your ISP facilities? Or installed in the customer computer? If the latter, do you want something to support all OSes?

Web filter
 

To make it clear our main aim is to block porn sites and we intend to install the the web filter at our system not at the customer's computer.
I was checking safesquid and I don't know if there is anybody there who have tried it, but I preffer something releable.