I'm looking for an external network monitoring program that I could install on my own Linux or Windows server. External, in that I'd like to monitor remote systems across the Internet without needing to rely on SNMP or the presence of any agent running on the monitored computers. In a perfect world, this program would meet the following requirements.
- Open source
- Downtime notifications by email, pager, SMS, or phone call... a phone call would be my ideal.
- I can define the polling frequency
- Checks against specific services can be run, e.g., DNS, SMTP, IMAP4, WWW, FTP, etc without using SNMP or an agent
I'm familiar with many internal network monitoring programs, OpenNMS, Nagios, Zenoss, and commercial programs like OpenView, Solarwinds Orion, Big Brother, etc.. but maybe not enough... I'd ideally like recomendations and specific links to pages that show the program is close to (though exactly would be great ;-) what I'm looking for.