While open source mainly moved from strength to strength in 2005 it wasn't all one-way traffic.
The move may work. The niche where the software works, network security, is dominated by proprietary programs. Nessus, in its open source form, was losing market share. The hope is that, as a proprietary program, it can advance against rivals, and make money doing it.
But it won't be easy. Tenable sacrificed goodwill within its user base through its decision. Nessus 2.0 has been adopted by a group called the OpenVAS Project, which has launched a fork. Software in the Public Interest, which counts Debian Linux among its projects, has given the fork its blessing.
The whole software industry will be watching closely how Tenable does in 2006. (Open source developers who feel underappreciated will be watching most closely.) If Tenable gains market share in the enterprise space, any losses among Linux users will be more than offset.
If enterprises decide they prefer to pay for Nessus 3.0 rather than go with OpenVAS, that will justify its decision further, and could encourage other Little Red Hens to do the same. And it should serve as a warning to all those who take open source work for granted that, without both give and take, value can easily be lost.