How to filtering pornography sites with no cost ?. Use these tools to implement your objective:
- Linux OS
- Dansguardian or SquidGuard (www.dansguardian.org and www.squidguard.org)
- Squid Proxy/Cache Server (www.squid-cache.org)
- IPTables (www.iptables.org)
Check and learn those tools from their sites. I have been try in my networks and the result is satisfied me. Although the free database (from BigURLBlackList) just contain hundred thousand of urls/domains (comparing with the commercial database that have million of urls from Websense or ISS for example). But it is enough for our network…
You can use the Dansguard Linux Server as a gateway to your ISP like the diagram below:
Or you can use your default router as a gateway for all of yours workstation and use PBR (Policy Based Routing) or WCCP (Web Cache Communication Protocol) to forward every HTTP traffic to Dansguardian Server. For this purpose, you must enable the transparent proxy option in Squid, and use Redirect option in the IPTables. All of those application running in one server. You don’t need to set the proxy server address on every workstion browsers, just use the existing default gateway.
One of disadvantage for use these implementiation is your networks public IP Address is just one, that is your Dansguardian IP Address, because Squid and IPTables is NAT-ing your workstation IP Address. One solution to prevent NAT-ing process (so your workstation can still use it local IP) is use TProxy option in IPTables. But for this purpose, you must recompile your Linux Kernel and your IPTables application to support TProxy.
Use the links below to learn furthermore:


Irwan Piesessa, born in Jakarta 27 years ago. passing CCIE Routing and Switching ( #20298 ) certification just now in the early of 2008. Want to be a specialist in Service Provider Technology and Network Security Field...
