Teaching a kid science at Tara, I realized that they have little or no access to the internet. On asking I learnt that the problem was twofold:
- they are donated laptops, which are pretty costly to maintain
- they didn’t know how to ensure that pornography and other harmful material was blocked
- wanted to prevent excessive downloads
So, seeing a technical challenge I asked them for a working machine and decided to have a go at it. They did and I got started with some research about how this could be done. My keyword was “parental control”. I looked for material on both Windows and Ubuntu. Actually, my search around Windows was half-assed and I didn’t really find much of interest there. My interest in Ubuntu was:
- Security through obscurity – the kids were not familiar with it, nor the others, so changing settings would be hopefully not something they’d do easily.
- Sheer amount of free software available under Linux
- Protection from malware – lots of it is written for Windows
- Exe files don’t execute well on Linux
- Desire to experiment a bit
- No license costs
So, my research turned up some interesting bits of info:
- OpenDns has free DNS servers which can effectively block access to sites that concern parents
- DansGuardian with a proxy server can filter out tons of stuff based on keywords in the page and url
- quota limits aren’t too hard on Linux – they’re almost built-in to the system
So I decided on working on two layers. I’d have OpenDNS serve dns queries as a layer 1 blocker. Then for layer 2 I’d use DansGuardian.
Configuring that was pretty easy. In the networking panel, you just set the DNS to the ones provided on the OpenDNS site and that should block pretty much all the easy sites and it’s kept up to date. I’ll probably also recommend that they set their routers to use OpenDNS as well.