Hi,
Ever wondered what if computer system can update you on the failure of critical service?
Nagios is an alerting & monitoring system, it provides alerts on Mail, Sms. It can monitor your network & servers using SNMP, providing you utilization graphs & service alters.
pnp4nagios is to get RRD graphs for utilization.
Nagvis is to get general overview of services / hosts being monitored.
Advantage:
You can monitor all your critical services, e.g dns, www, ftp, mail … etc
It can also be used to monitor tcp ports, e.g you have critical service running on tcp 5000.
Disadvantage (only for windows admins):
There is no front end to add hosts & services. Although there are few php based frontends available.
Windows users may consider other monitoring tool available
Cacti
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