Nagios is an extremely powerful monitoring system that enables users and organizations to monitor critical IT infrastructure components, including network protocols, applications, servers, system metrics, services, and network infrastructure.
The main purpose of Nagios monitoring system is to monitor services that run on or are provided by physical hosts or
devices on your network. Nagios has been designed to run under the Linux operating system, but works fine under *nix and its variants. It optionally requires a Web server to be installed. Nagios will watch hosts and services that you specify and alert you when things fail and recover. It sends alerts when critical components fail and recover and thereby provides administrators alerts of important events. There are many ways a user could configure Nagios to send notifications out.
The possible notification methods are:
Yahoo, ICQ, or MSN instant message
Audio alerts, etc
Its up to a user to decide which method to use. Once the alert is received the user can begin investigating the alerts and resolving any outages.
Nagios has an excellent list of features that include:
Monitoring the server resources.
Real time notification of failures and recoveries
Monitoring of network services like DNS, IMAP, HTTP, SQL, SMTP, FTP, SSH, etc.
Detailed Web interface
Fairly simple plugin development process.
Licensed under the GNU GPL
The above screen shot shows you that it has an easy to navigate web-interface. Current status information of a component, logs, and reports can all be accessed via a web browser. The reports provide a detailed historical record of any outages, events, and alert for a user to review.
Nagios is considerably a robust and full-featured monitoring system that any system manager would want. It enables the network administrator to keep a very close watch on all systems and alerts them when something goes wrong. It is an outstanding network monitoring tool. Nagios can be customized to best suit your needs.