As an administrator you may be face with the task of constantly monitoring web servers, mail servers, ftp servers, etc. Basically, your organization wants all of their servers up and running all of the time. Nagios 3 offers an easy set up and configuration to make this happen so that you can monitor multiple servers and have Nagios alert you to problems. Nagios can notify you by email, pager or phone. This will allow you to have a life and count on Nagios to contact you when problems develop.
In the past Nagios has been a real difficult set up and configure job. Many have just given up and moved on. However, using Ubuntu 8.10 and the new Nagios 3 this is a breeze to set up and use effectively. Here are some key links to get you going:
Nagios is based on Objects. Objects are hosts, services, contacts and timeperiods. A host is a physical device on your network like a server, router, switch or printer. Each of these hosts has an IP Address or MAC Address that you can use to monitor it with. A service is an attribute of the host. For example a service might be CPU load, disk usage, or uptime. A service might also be something that the host provides like HTTP, FTP, or POP3. Once you have set up a host and as service, Nagios will begin to monitor that service on the host. The contacts are the administrators that should get notified and how they should get notified when there are problems. Finally, timeperiods are blocks of time that determine when an administrator should get notified by Nagios. Put this all together, and you have a sophisticated monitoring process that will make your life easier.
Nagios has a web interface that you may log into so that you can see various hosts and services that you are monitoring. Here is an example.