Monthly Archives: October 2012

Protecting the kids from the Internet!

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.

DansGuardian is pretty easy to use too. Here’s a quick tutorial that shows you how to get it up and running. I used TinyProxy instead of Squid though.

Wow, this blog’s grown!

Just the other day I was checking the stats on my blog and was pleasant to surprised with them!

With over 200 posts on this blog, the number of visitors has risen to an all time high of just over 1,100 visitors a month in September! And looking at it year on year, in terms of growth, here are the figures from 2010 and 2011.

September 2010: 19 views
September 2011: 102 views
September 2012: 1,134 views

That’s almost a 10 fold increase year over year for two years! And the numbers are on the up and up in general.


And so, a bit thank you to you all. This is excellent motivation to keep writing, even when I think it’s taking me away from the “real” writing I want to do!

Google Calendar sync issue with Lightning

So, I ran into a bit of an issue when my Lightning on Thunderbird stopped syncing with my Google calendar. I noticed this when I tried creating an event, but did not find it on the calendar. I upgraded to the latest version of Thunderbird (15) and the add-on manager automatically updated the Lightning version. I thought the issue would be resolved. It wasn’t.

Turns out the culprit in my case was the Provider for Google Calendar. The version installed on my machine was 0.13 while the version available was 0.16. Auto updates hadn’t kicked in. When I manually performed the upgrade, I had to recreate the links to the calendars, but everything started working smoothly after.