Install and configure Check_MK Server on CentOS 7

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Are you looking for an IT monitoring solution that is free and open source as well as compelling with latest technologies? Check_MK Server is one of the best monitoring system out there that was started originally as an extension to the Nagios monitoring system.

It supports creating a rule-based configuration using Python and also allows monitoring of more machines from a single Nagios server. Specifically, Check_MK Server can handle a pleura of monitoring tasks including Server, Application, Network, Cloud, Storage, Database, Environment, and Container. That’s almost everything even a large organization will ever need.

Here we are going to install and configure the CRE version (Check_MK Raw Edition) which is open-source and 100% free.

Install and Configure Check_MK Server on CentOS

Launch terminal and login as root.

Step 1 – Disable SELinux

Let’s check SELinux status and disable it if it’s enabled.

getenforce

Edit SELinux configuration file:

vim /etc/sysconfig/selinux

Change SELINUX=enforcing to SELINUX=disabled

Save and exit the file followed by a reboot.

reboot

Step 2 – Installing Prerequisites

Let’s start with updating the system.

yum update

Next, install NTP and check its service status.

yum install ntp

systemctl status ntpd

If the service is not started, start it using below command:

systemctl start ntpd

Enable NTP on system boot:

systemctl enable ntpd

Modify firewall rules to allow NTP service. Run the following commands to enable service.

firewall-cmd --add-service=ntp --zone=public --permanent

firewall-cmd --reload

Step 3 – Add EPEL Repository to the System

We have to install EPEL repository because some of the check_mk packages are not available in default repositories.

yum install epel-release -y

List repository.

yum repolist

Step 4 – Install Check_MK

We are going to download a free version of check_mk. Head over to the official download page and copy the relevant link to use in the command below after wget.

wget https://mathias-kettner.de/support/1.5.0p12/check-mk-raw-1.5.0p12-el7-38.x86_64.rpm

Install Check_MK and all the dependencies required for Check_MK.

yum install check-mk-raw-1.5.0p12-el7-38.x86_64.rpm

Now modify Firewall rules for HTTP.

firewall-cmd --add-service=http --zone=public --permanent

firewall-cmd --reload

Step 5 – Create and start Check_MK server

Check “omd ” command if it works or not.

omd version

Configure the Check_mk server

To create Check_MK server run following command:

omd create fosslinuxmonitor

You can replace “fosslinuxmonitor” with whatever the name you want.

omd create fosslinuxmonitor

Then you should get a similar output as below:

Here you can see web URL, username and password for login.

Start created server:

omd start fosslinuxmonitor

Step 6 – Access Check_MK on Webbrowser

When you create Check_MK server, it shows Web Interface URL. You can use it to access your Check_Mk Server.

http://<servername>/<instance_name>/

Eg:- http://10.94.10.208/fosslinuxmonitor

You can use username and password which showed on Check_Mk server creation. Then you can access the Dashboard.

Step 7 – How to install the Check_Mk agent on Linux client

You can download check_mk Agents from the following URL

http://<servername>/<instance_name>/check_mk/agents/

Eg:- http://10.94.10.208/fosslinuxmonitor/check_mk/agents/

Check-MK AgentsOn Ubuntu Server, install “xinetd” before installing Check_MK agent.

apt-get install xinetd

Download and install the agent.

wget http://10.94.10.208/fosslinuxmonitor/check_mk/agents/check-mk-agent_1.5.0p12-1_all.deb

dpkg -i check-mk-agent_1.5.0p12-1_all.deb

In addition to that Port 6556 TCP should be open between check_mk server and client for communication. Install Check_MK agent on CentOS.

Install “xinetd”.

yum install xinetd

Download and install the agent.

http://10.94.10.208/fosslinuxmonitor/check_mk/agents/check-mk-agent-1.5.0p12-1.noarch.rpm

rpm -ivh check-mk-agent-1.5.0p12-1.noarch.rpm

Install Agent On Microsoft Windows server. Download agent.

http://10.94.10.208/fosslinuxmonitor/check_mk/agents/windows/check_mk_agent.msi

Install agent using “msi” package.

Click finish after installation.

Step 8 – Add Hosts in check_mk monitoring

Now click on WATO configurations > Hosts > Create new host.

Then fill host details, Hostname, IP address.

Now click ‘Save & Goto services‘. You will get below the screen in which check_mk discovers services on the client.

Then click on “Activate changes ” to activate all configurations.

You can add more host like this. In my case, I have added CentOS, Ubuntu and MSWindows machine. Click On WATO configurations > Hosts and you can see all added hosts.

Click on Views -> Hosts -> All Hosts. You can see all the added host status.

Step 9 – Add New User to Get email alerts

Click on WATO configurations > Users.

You can add user name, email etc. In addition to that select “Receive fallback notifications” too.

Save, click changes and activate it. Now go to WATO configurations > Hosts and click on any Host. In the Basic Settings area move “Everything ” to the selected area.

Save and do the same to all hosts. Click on hosts

Click on changes and activate it.

Step 10 – Check email Alerts

Now we will shut down one machine. You should see hosts status as Down.

Now we get Email alert.

You will get other systems alerts similar to this. After you start the server you will get another alert.

You can integrate alerts with Slack, Pager durty and so on.

Now you successfully installed and configured Check_MK server on CentOS. Let us know your experience in the comments below. Also, please don’t forget to share the tutorial with your friends on social platforms.