Nagios Vs. Icinga: the real story of one of the most heated forks in free software

In March 14, 1999 Ethan Galstad released the first version of Nagios. Then, nearly exactly 10 years later (May 2009), Icinga (a fork of Nagios) was born. What happened there? Why a fork? In this article, I will shed some light about what made the Icinga developers decide to fork (although they still send patches to Nagios). In this article, I will talk to both Ethan Galstad himself, and Michael Lübben (one of the founding Icinga team members and Nagios addon developer). I will quote Michael and Ethan in the article.