Emon
Remote server monitoring application
...You do not need to install any applications on the monitoring servers, because Emon uses SSH and /proc directory to get the monitoring data. All you need to do is just configure Emon in XML and create an SSH user. After configuration, you are ready to monitor ping, dns, ports, url, CPU, RAM, SWAP, disk, traffic and log files of multiple servers in the terminal. If something goes wrong, Emon will send email to the admin. Emon is able to send the statistics (dropouts and graphs) to the admin.