jgoguen writes "Nagios, originally known as Netsaint, has been a long-time favourite for network and device monitoring due to its flexibility, ease of use, and efficiency. Nagios provided, and still provides today, a low-cost, versatile alternative to commercial network monitoring applications. Nagios 3 takes a huge step forward compared to Nagios 2, providing improved flexibility, ease of use and extensibility, all while also making significant performance enhancements. Due to its extensibility and ease of use, no device or situation has yet been found that cannot be monitored using Nagios and a pre-made or custom script, plug-in or enhancement." Read on for the rest of jgoguen's review.