I had one of those lightbulb moments the other day while pondering a problem I recently encountered relating to firewall changes.
The problem came to light the morning after some firewall rules had been modified, nothing new there I hear you say.
Of course at the time everything looked to be working, that is from the perspective of the few people that were actually working that late in the night. It was only when the morning came and the rest of the business started to come online that the problems were apparent. It didn’t take long to fix the problem but it got me thinking, how could we prevent this in future?

I have been spending some time looking at Unit testing recently and began to wonder if there were any testing tools or frameworks that could be used to prevent this kind of problem in future. Unit testing for software is pretty much standard practice nowadays and works well during the development phase, but once the application is in situ how can you test the operation from a networking perspective?. Web testing tools are great for validating web application functionality and I’m pretty sure there are loads of other test frameworks out there, but are they easy to use? I wanted a way to describe and validate the problem before and after the work was undertaken, and so NetUnit was born…

NetUnit aims to be simple to use, something I could give to a non-techie and have them run a Test Suite to validate connectivity or application functionality. NetUnit mimics Apache Ant in its operation and design, in fact I was going to write some Ant tasks at first but kept thinking of new ways to extend the tool in future.

The Test Suite used to describe the Tests to perform is a simple XML file. NetUnit parses this file and outputs the result of each test along the way – simple huh!.

Another benefit of this tool that immediately sprung to mind was the ability to take a Test Suite file and generate documentation for your applications external network interface or firewall policies. In fact the ideas don’t stop there and I have quite a list of features that could be implemented in future. Time permitting as always….