Nagios 2.9

Nagios (formerly Netsaint) is a daemon written in C that is designed to monitor networked hosts and services.
Nagios project has the ability to notify contacts (via email, pager or other methods) when problems arise and are resolved. Host and service checks are performed by external "plugins", making it easy to write custom checks in your language of choice.
Several CGIs are included in order to allow you to view the current and historical status via a Web browser, and a WAP interface is also provided to allow you to acknowlege problems and disable notifications from an internet-ready cellphone.
Main features:
- Monitoring of network services (SMTP, POP3, HTTP, NNTP, PING, etc.)
- Monitoring of host resources (processor load, disk and memory usage, running processes, log files, etc.)
- Monitoring of environmental factors such as temperature
- Simple plugin design that allows users to easily develop their own host and service checks
- Ability to define network host hierarchy, allowing detection of and distinction between hosts that are down and those that are unreachable
- Contact notifications when service or host problems occur and get resolved (via email, pager, or other user-defined method)
- Optional escalation of host and service notifications to different contact groups
- Ability to define event handlers to be run during service or host events for proactive problem resolution
- Support for implementing redundant and distributed monitoring servers
- External command interface that allows on-the-fly modifications to be made to the monitoring and notification behavior through the use of event handlers, the web interface, and third-party applications
- Retention of host and service status across program restarts
- Scheduled downtime for suppressing host and service notifications during periods of planned outages
- Ability to acknowledge problems via the web interface
- Web interface for viewing current network status, notification and problem history, log file, etc.
- Simple authorization scheme that allows you restrict what users can see and do from the web interface
Enhancements:
- Fix for incorrect performance data file write/append mode options
- Fix for current status of hosts with no host check command defined
- SIGSEGV signals should now be logged again (broken in 2.8)
- Configure script fix for no mail program found/installed on system
- Configure script option bug fixes for cygwin and embedded perl
- Command definitions and host/service plugin perfdata with HTML should now be escaped in CGIs
- Patch for incorrect time down percentage in availability CGI
- Updated init script to fix a race condition during restarts