I was getting the odd spam comment on my posts in this blog, and they were starting to irritate me, so I added an anti spam feature to the blog. It is Block-Spam-By-Math by Alexander Grau. It appears to work very well at blocking spam, in that I have had no comments at all since I put it on. I have only really had spam for a few months anyway, so that was to be expected.

A few weeks before I did this I also added anti-spam to my web site which is written in HTML, CSS with a PHP backend (no javascript). It’s a bit like the Block Spam  By Math but I wrote it myself in PHP. Nothing really clever about it, just two random numbers between one and nine, and a random simple action (add, subtract, multiply), with a bit of manipulation to make sure that the answer is never negative. Just to make it less readable to robots (if they are that clever) it translates numbers and signs into english words, and disguises the posted returned figures. You can see it working here.

Incidentally, I have nothing against javascript, and love using it for ajax type applications etc, but I decided that this website would be HTML and CSS only, it really does simplify things at times.


Dave Glover is a director of Signs of Success Ltd. married to Lynn (the other director of SOS) with 3 grown up kids. We live in Whitby, in New Zealand. After 30+ years in IT as everything from Trainee Programmer to Project Manager, Dave now runs a Computer Maintenance and Sign Making shop near his home.

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