squid-site restriction

[Selvi]

We are using  squid-2.3.STABLE4-10 proxy under Redhat 7.1.  i need to restrict all porno sites in our network. If there is one or two  sites we can restict easily by adding the site name in squid. But it is not possible to add every site. . Because now a days lots of site is there. How can i restrict all the sites by easiest way?   Is there any program or batch file which contains all sites name which are not allowed in our network?