This content filter uses Squid and Dansguardian to work.
About Squid

Squid is a high-performance proxy caching server for web clients, supporting FTP, gopher, and HTTP data objects. Unlike traditional caching software, Squid handles all requests in a single, non-blocking, I/O-driven process.

About Dansguardian

DansGuardian is a web content filter which currently runs on Linux, FreeBSD, OpenBSD, NetBSD, Mac OS X, and Solaris. It filters the actual content of pages based on many methods including phrase matching, PICS filtering and URL filtering. It does not purely filter based on a banned list of sites like lesser totally commercial filters.

DansGuardian is designed to be completely flexible and allows you to tailor the filtering to your exact needs. It can be as draconian or as unobstructive as you want. The default settings are geared towards what a primay school might want but DansGuardian puts you in control of what you want to block.

How to configure OS X to use the Content filter.

Local settings:

1. Open the Network control in System Preferences select the Proxy tab.
2. Set the Web proxy to localhost and the port to 8080
3. Set the Secure Web proxy to localhost and the port to 8080
4. Set the FTP proxy to localhost and the port to 3128
5. Set the Gopher proxy to localhost and the port to 3128
6. click apply now and lock the panel by clicking on the lock icon

To provide this service as a server for others.
Replace the word "localhost" with the IP of your server on the CLIENT machines.
Open ports 3128 and 8080 on your servers firewall.

DOWNLOAD

--- Select a FTP or HTTP Mirror --- ---------- HTTP Mirrors ----------- HTTP - WW2.OSXGNU.ORG United States HTTP - FR.OSXGNU.ORG France HTTP - IT.OSXGNU.ORG Italy ----------- FTP Mirrors ----------- FTP - US.OSXGNU.ORG United States FTP - FR.OSXGNU.ORG France OS X 10.2.x or above ONLY!