SquidGuard is a URL redirector used to use blacklists with the proxysoftware Squid. There are two big advantages to squidguard: it is fast and it is free.
Make UNIX work with Windows XP and Mac OS X
Learn about using a UNIX® system as a primary domain controller (PDC) and file repository, including an anonymous, read-only shared area accessible by anyone with a Web browser. To be a good citizen on your local network, you need to integrate your favorite UNIX system with the networking features of client systems, generally running Windows® XP or Mac OS X. This makes it easier for the users of those workstations to take advantage of the centralized authentication and storage facilities you can provide.