Nagios open source system monitor software

Tuning Nagios

In order to allow the Nagios system to run thousands of alert checks per minute, we needed to tune a few things in Nagios.

First we moved the database and program directories /var/lib and /usr/local over to a high speed EMC disk Array.

Create a RAM disk for Nagios tempory files

I created a ramdisk by adding the following entry to the /etc/fstab file:

none                              /mnt/ram                        tmpfs   size=500M           0 0

Mount the disk using the following commands

# mkdir -p /mnt/ram; mount /mnt/ram


Setting up NRPE on Linux

NOTE: These instructions apply to a system that has not previously had NRPE installed on it.  If NRPE has been previously installed, you will need to backup the nrpe.cfg file to ensure it is not lost.

NOTE2: The system you are installing this on MUST have access to your nagios server on port 80.  You can verify this by typing "telnet 80".

1. Install rpmforge on the linux system

Please refer to this document on installing it if you have not already:

2. Next: install nagios-nrpe on the system

rpm -q nagios-nrpe ||  yum --enablerepo=rpmforge install nagios-nrpe


Alert Types to setup in Nagios

a.  Regular Expression HTTP monitor

We need the ability to monitor a part of a page.   The content needs to be able to match content on a page using regular expressions.  Also needed is the ability to log into the page.  Example of expression: /Temp_P18.*\n.*\n.*;(.*) Deg. C.*\n.*\n.*\n.*;(.*) %/

We need to be able to catch the values in the "()" areas listed above and check against those values.

We're experiencing issues with some monitors giving a HTTP-FORBIDDEN issue with the check_http scripts.



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