While configuring and testing nagios monitoring, you may sometimes get the above error. Then check for the following.

In the remote server being monitored,

1) Check the file /etc/xinetd.d/nrpe. Make sure that the only_from field contains the nagios server IP, which is shown as x.x.x.x below.

# default: on
# description: NRPE (Nagios Remote Plugin Executor)
service nrpe
{
flags = REUSE
socket_type = stream
port = 5666
wait = no
user = nagios
group = nagios
server = /usr/local/nagios/bin/nrpe
server_args = -c /usr/local/nagios/etc/nrpe.cfg –inetd
log_on_failure += USERID
disable = no
only_from = 127.0.0.1 x.x.x.x
}
2) In the remote server being monitored, make sure that the nagios IP is added to the allowed_hosts section of the file /usr/local/nagios/libexec/nrpe.cfg

allowed_hosts=127.0.0...

Here, our requirement is to monitor a site and if it returns internal server error, alert us through the nagios interface. Here the monitoring tool checks if the domain returns a 500 error and if it does restart the web service. This is applicable for cases where internal server error is caused due to fast cgi issues.

Checking is done using NRPE, installed in the server being monitored. Install NRPE and nagios plugins.

yum install nagios-nrpe

Adaptec RAID can be monitored using the NRPE plugin which needs to be installed in the nagios server as well as the server being montiored.

Steps to be performed on the server being monitored:
————————————————-

First check the architecture of the server and make sure you download the appropriate source files.

root@host [~]# arch
x86_64

Here its a 64 bit system.

arcconf is the command line utility for Adaptec based RAID.

root@host[~]# mkdir /usr/StorMan/
root@host[~]# cd /usr/StorMan/
root@host[~]# wget http://www.obvious.co.nz/aacraid/arcconf/arcconf-x64-6.10-b18350.tgz
root@ho...

Monitoring 3ware RAID using Nagios

RAID (Redundant Array of Inexpensive Disks) is used for storing the same data in multiple places, which provides a redundant and reliable means of data storage. While you improve the security of your data using RAID, what will happen if something happens to the RAID array itself? Its always better to have a monitoring in place for the RAID you have setup, so that it will alert you even when a minor problem is noticed. Here I am explaining the steps to monitor a 3ware RAID using the monitoring tool, NAGIOS.

We are using a command line tool called tw_cli for monitoring 3ware RAID arrays. The tw_cli needs to be installed in the remote host, the host being monitored...