You had read about nagios plugin which I use in my firefox browser in my previous articles. Let me give you an insight about nagios remote server monitoring. Nagios has been a reliable monitoring tool for many clients for years now.
Nagios comes with lots of plugins which can be used to fine tune the results. While monitoring the remote servers we need to check the service status locally on those servers to understand the condition of service status. check_nrpe is one of those tools which facilitates this feature on Nagios.
The NRPE addon is designed to allow you to execute Nagios plugins on remote Linux/Unix machines. The main reason for doing this is to allow Nagios to monitor “local” resources (like CPU load, memory usage, etc.) on remote machines. Since these public resources are not usually exposed to external machines, an agent like NRPE must be installed on the remote Linux/Unix machines.
The NRPE addon consists of two pieces:
- The check_nrpe plugin, which resides on the local monitoring machine
- The NRPE daemon, which runs on the remote Linux/Unix machine
When Nagios needs to monitor a resource of service from a remote Linux/Unix machine:
- Nagios will execute the check_nrpe plugin and tell it what service needs to be checked
- The check_nrpe plugin contacts the NRPE daemon on the remote host over an (optionally) SSL-protected connection
- The NRPE daemon runs the appropriate Nagios plugin to check the service or resource
- The results from the service check are passed from the NRPE daemon back to the check_nrpe plugin, which then returns the check results to the Nagios process.
Note: The NRPE daemon requires that Nagios plugins be installed on the remote Linux/Unix host. Without these, the daemon wouldn’t be able to monitor anything.
Today I found the answer for one of my questions. I wanted to monitor a server which is not directly connected to internet. I used the above mentioned NRPE plugin to check the status of MySQL service via an another server which had privilege to interact with the db server. It has been made possible via Nagios Indirect checks via check_nrpe. You can find the block diagram explaining the same below.
Its quite easy to configure this just like any other remote service checks done via nrpe daemon. Now I can monitor anything on servers which are locked in a DMZ. Nagios and NRPE made for each other.
Read more : Nagios
