Cacti is a monitoring application.
After installation it’ll be available at http://localhost/cacti/
When you’ve configured the graphs via the web interface, you’ll need to have cron run its poller.php script in order to have it monitor. I found it best to run the job as the apache user.
*/5 * * * * /usr/bin/php /var/www/localhost/htdocs/cacti/poller.php > /dev/null 2>&1
