Objective
The objecte is to describe the procedures to a manual installation of the monitoring agent on Linux, platforms, in order to monitor with the OpMon.
Target audience
It is intended for OpMon administrators and for IT teams that are already familiar with the installation of Linux apps and with the configurations of the OpMon in order to monitor equipment that are running with RedHat, CentOS, Ubuntu, Suse, among other distribuitions.
Solution
In order the optimize the installing process of the agent HP-UX, the OpServices has created an automatedinstalling package, containing the NRPE + NagiosPlugins + OpServicesPlugins. For those who want to performthe installation of this package, click here and follow the steps.
It is possible to replicate the agent if you already have the agent installed on a certain distribuition and want to replicate it to another. For example, if you already have the agent installed on a CentOS and want to replicate it on another CentOS without any installation process, just click here and follow the steps. For those who want to perform the installation manually, follow the steps below.
The agent must be installed on the target Linux machine and afterwards configured on the OpMon, making it thus possible to monitor system metrics, services, processes, performance data, among others. In order to conduct the installation process, the files NRPE and NagiosPlugins will be used, which may be downloaded, as of their latest version, on the following address:
The download link is available on the NRPE page: [ NRPE ]
The download link is available on the NagiosPlugins page: [ NagiosPlugins ]
Troubleshooting
In case you find any problem or error during the process, find your answer in our knowledge base, clicking here.
1) Obtaining the Agent
Logging as the root of the target server and later download the files, as shown below:
[root@localhost]# cd /tmp [root@localhost tmp]# wget https://nagios-plugins.org/download/nagios-plugins-2.2.1.tar.gz [root@localhost tmp]# wget --no-check-certificate https://downloads.sourceforge.net/project/nagios/nrpe-2.x/nrpe-2.15/nrpe-2.15.tar.gz
2) Creating a user
It is necessary to create a user, normally with the following definitions: opuser, according to the example given below.
[root@localhost tmp]# adduser opuser -d /usr/local/opmon -g users -s /bin/bash -c "OpMon NRPE" [root@localhost tmp]# passwd opuser
Remember to set a secure password for this user, or create without permission to log in to the system using this command below:
[root@localhost tmp]# adduser opuser -d /usr/local/opmon -g users -s /sbin/nologin -c "OpMon NRPE"
3) Preparing the requirements
Some packages are required for the installation, they are:
gcc, openssl, net-snmp e xinetd
Therefore, based on a RedHat or a CentOS installation, use the following command to install:
[root@localhost tmp]# yum install gcc openssl-devel net-snmp-utilis xinetd -y
Afterwards, we will adjust the xinetd to run the boot, once it will be important in this process:
[root@localhost tmp]# chkconfig --level 2345 xinetd on
To unpack the packages previously obtained by downloading, we will use the same temporary folder and follow the steps as shown below:
[root@localhost tmp]# cd /tmp [root@localhost tmp]# tar xvfz nagios-plugins-1.4.16.tar.gz [root@localhost tmp]# tar xvfz nrpe-2.13.tar.gz
4) Installing the Plugins
On the nagios-plugins directory created, you have to run the following command listed below:
[root@localhost tmp]# cd nagios-plugins-1.4.16 [root@localhost nagios-plugins-1.4.16]# ./configure --prefix=/usr/local/opmon --with-nagios-user=opuser --with-nagios-group=users
If no errors are found, run the “make” commands shown below on the same directory.
[root@localhost nagios-plugins-1.4.16]# make all ; make install
If all goes well, the following folder containing plugins will be created: /usr/local/opmon/libexec
5) Installing the NRPE
On the created nrpe directory, run the following command as listed below.
[root@localhost nagios-plugins-1.4.16]# cd ../nrpe-2.13 [root@localhost nrpe-2.13]# ./configure --prefix=/usr/local/opmon --with-nrpe-user=opuser --with-nagios-user=opuser --with-nrpe-group=users --with-nagios-group=users --enable-command-args
If all goes well, run the “make” commands shown below on the same directory.
[root@localhost nrpe-2.13]# make all
In order to install the check_nrpe and the nrpe.
[root@localhost nrpe-2.13]# make install
In order to install the nrpe.cfg.
[root@localhost nrpe-2.13]# make install-daemon-config
In order to install the xinetd.
[root@localhost nrpe-2.13]# make install-xinetd
6) Fine adjustments
To get an easier setup, we will adjust the nrpe allowing it the use of arguments.
[root@localhost]# vim /usr/local/opmon/etc/nrpe.cfg
Look for the dont_blame_nrpe file and change it to 1.
dont_blame_nrpe=1
Change the permission of the directory for the opuser user.
[root@localhost]# chown -R opuser:users /usr/local/opmon/
Insert the following line at the end of the file /etc/services.
[root@localhost]# vim /etc/services nrpe 5666/tcp # OpMon Agent
7) Testing the Plugins
To validate whether the plugins are working, some tests are necessary. Once everything is correct, the result displayed must be similar to the one below:
[root@localhost]# cd /usr/local/opmon/libexec/ [root@localhost libexec]# ./check_load check_load: Could not parse arguments Usage: check_load [-r] -w WLOAD1,WLOAD5,WLOAD15 -c CLOAD1,CLOAD5,CLOAD15 [root@localhost libexec]# ./check_http -H www.google.com HTTP OK: HTTP/1.1 302 Found - 1009 bytes in 0.219 second response time |time=0.218719s;;;0.000000 size=1009B;;;
8) Starting the Agent
Basically there are 3 options to initialize the agent: xinetd (recommended), inetd or daemon.
- To initialize with the xinetd
To allow the OpMon to perform the monitoring, we need to release its IP for queries, thus, we need to edit the file, adding the IP on line only_from. You can also add more IPs or used range. For example: OPMNON_IP24. If you want to release any IP, just remove the only_from line. [root@localhost]# vim /etc/xinetd.d/nrpe
[root@localhost]# vim /etc/xinetd.d/nrpe
service nrpe
{
flags = REUSE
socket_type = stream
wait = no
only_from = 127.0.0.1 IP_DO_OPMON
user = opuser
server = /usr/local/opmon/libexec/nrpe
server_args = -c /usr/local/opmon/libexec/nrpe.cfg --inetd
log_on_failure += USERID
disable = no
}
To conclude, restart the xinetd
[root@localhost ]# service xinetd restart Stopping xinetd: [ OK ] Starting xinetd: [ OK ]
- To initialize with the inetd
Insert the following line on the file /etc/inetd/.conf .
[root@localhost]# vim /etc/inetd.conf nrpe stream tcp nowait opuser /usr/sbin/tcpd /usr/local/opmon/bin/nrpe -c /usr/local/opmon/etc/nrpe.cfg --inetd
To conclude, restart the inetd.
[root@localhost libexec]# service inetd restart Stopping inetd: [ OK ] Starting inetd: [ OK ]
- To initialize with the daemon
To allow the OpMon to perform the monitoring, we need to release its IP for queries, thus, we need to edit the file, adding the IP on line allowed_hosts. You can also add more IPs or used range. For example: OPMNON_IP24. If you want to release any IP, just remove the allowed_hosts line.
[root@localhost]# vim /usr/local/opmon/etc/nrpe.cfg allowed_hosts=127.0.0.1,IP_DO_OPMON
To conclude, restart the daemon
[root@localhost]# /usr/local/opmon/bin/nrpe -c /usr/local/opmon/etc/nrpe.cfg -d
9) Testing the access locally
To verify if the port 5666 is available for connections, use the following command and check if the output is similar to the one below:
[root@localhost]# netstat -vantup | grep 5666 tcp 0 0 0.0.0.0:5666 0.0.0.0:* LISTEN 2202/xinetd
To verify the communication of the NRPE:
[root@localhost]# /usr/local/opmon/libexec/check_nrpe -H 127.0.0.1 NRPE v2.13
Running a query load through the NRPE.
[root@localhost nrpe-2.13]# /usr/local/opmon/libexec/check_nrpe -H 127.0.0.1 -c check_load -a none OK - load average: 0.02, 0.03, 0.00|load1=0.020;15.000;30.000;0;load5=0.030;10.000;25.000;0; load15=0.000;5.000;20.000;0;
10) Testing the access through the OpMon
From the console of the OpMon, it is possible to verify the NRPE communication when the following command is executed, setting the IP_DO_SERVIDOR where the agent was installed.
[root@opmon]# /usr/local/opmon/libexec/check_nrpe -H IP_DO_SERVIDOR NRPE v2.13
Running a query load through the NRPE.
[root@opmon]# /usr/local/opmon/libexec/check_nrpe-H IP_SERVIDOR -c check_load -a none OK - load average: 0.02,0.03,0.00|load1=0.020;15.000;30.000;0;load5=0.030;10.000;25.000;0;load15=0.000;5.000;20.000;0;
All right, what now?
After completing the installation process, the next step is to have the server start monitoring. In order to do so, you can access our Plugins and Templates base by clicking here to learn more.