Nagios is an open source
network monitoring tool. Nagios goes absolutely free, it is powerful and flexible open source software. It can be tricky to learn and implement, but can reduce enormously the amount of time required to keep track of how your organization's IT infrastructure is performing.
Nagios tools go by the generic name of network management software, and all share the capability to:
- Keep track of all the services and machines running in the infrastructure;
- Raise alerts before small problems become large ones;
- Run from a central location to reduce the need to physically go to each machine; and,
- Provide a visual representation of system-wide status, outstanding problems, etc.
Two main problems keep network management software from being more widely used:
- It tends to be extremely expensive; and,
- It requires significant work to configure for a given environment.
Nagios is an open source network management tool that solves the first problem. It too, requires a fair amount of configuration.
The Nagios application runs on Linux or Unix servers. Each piece of hardware that must be monitored runs a Nagios daemon that communicates with the central server. Depending on the instructions in the configuration files the central server reads, it will "reach out and touch" the remote daemon to instruct it to run a necessary check. While the application must run on Linux or Unix, the remote machines may be any piece of hardware that may be communicated with.
Depending upon the response from the remote machine, Nagios will then respond with an appropriate action, again, according to its configuration. Depending upon what remote test needs to be performed, Nagios will perform the test via a native machine capability (e.g., test to see if a file exists) or will run a custom test program (called a plugin) to test something more specific (e.g., check to see if a particular set of values has been placed into a database). If a check return value is not correct, Nagios will raise an alert via one or several methods -- again, according to how it has been configured.
Nagios frankly speaking is not very good but it's better than most of the alternatives. After all, you could spend tons of bucks on HP OpenView or Tivoli and still be faced with the same amount of work to customize it into a useful state. I can recommend free network monitoring by Dotcom Monitor. They offers free, 30-day trial and paid subscription. And you don't need special skills to configure your server. Support works 24 hours per day.