Monit

Key Features

* Proactive - Monit can act if an error situation should occur, e.g.; if sendmail is not running, Monit can start sendmail again automatically or if apache is using too much resources (e.g. if a DoS attack is in progress) Monit can stop or restart apache and send you an alert message. * Processes - You can use Monit to monitor daemon processes or similar programs running on localhost. Monit is particularly useful for monitoring daemon processes, such as those started at system boot time from /etc/init/ For instance sendmail, sshd, apache and mysql. * Files, Dirs and Filesystems - You can also use Monit to monitor files, directories and filesystems on localhost. Monit can monitor these items for changes, such as timestamps changes, checksum changes or size changes. * Cloud and Hosts - Monitor network connections to various servers, either on localhost or on remote hosts. * Programs and scripts - Monit can be used to test programs or scripts at certain times, much like cron, but in addition, you can test the exit value of a program and perform an action or send an alert if the exit value indicates an error. * System - Finally, Monit can be used to monitor general system resources on localhost such as overall CPU usage, Memory and Load Average.