How to monitor your Linux servers with Checkmk

How to monitor your Linux servers with Checkmk

As a system / network administrator, it’s up to you to keep an eye on the Linux servers in your data center (both on-premise and in the cloud). Since the Linux platform has a significant number of tools to help you monitor those servers, you may not know where to start. Among those many titles, there is one particular software package that you should definitely try. Said monitor is Checkmk.

Checkmk can monitor your servers, desktops, applications, networks and cloud environments, all from a well-designed web-based GUI dashboard.

I’ll walk you through the Checkmk installation process and then adding a monitoring agent. We will do both on Ubuntu Server 20.04, but be aware that this software supports Debian and RHEL based distributions.

There are two different versions of Checkmk:

  • Raw – the fully open source version which does not include all features.
  • Enterprise: Includes Free Edition (which limits you to 25 hosts after 30 days, Standard Edition and Managed Services). Find out more about pricing and features in the Checkmk editions matrix.

What you will need

To install Checkmk, you will need a running instance of Ubuntu Server 20.04 and a user with sudo privileges. That’s all. Let’s get the server monitor working.

How to install Checkmk

You won’t find Checkmk in the standard repositories. Instead, go to the download page and download the version you want to use or log into your Ubuntu server and issue the command:


We recommend that you capture the download URL by right-clicking the Download button (after selecting the desired version).

Once the download is complete, install Checkmk with:

sudo dpkg -i *.deb

The installation will fail. To fix this, issue the command:

sudo apt-get install -f

The above command will install all necessary dependencies for Checkmk.

How to create a Checkmk monitoring site

The next step is to generate everything you need for a Checkmk monitoring site (which is really just a fancy term for a Checkmk instance). We call our instance tr_test. We will create that instance with the command:

sudo omd create tr_test

The command output will give you the web-based GUI address and administrator login credentials for your instance. Once this is done, start the instance with:

sudo omd start tr_test

How to access the web-based GUI

Open a web browser and point it to http: // SERVER / tr_test (where SERVER is the IP address of the hosting server). Give the site time to load and then log in with the administrator credentials provided by the create command. After successful authentication, you will find yourself in the main Checkmk dashboard ( Figure A ).

Figure A


Checkmk’s main dashboard is ready for adding hosts.

How to add a new host

Checkmk is not monitoring anything at the moment. What we need to do is add a host. We will add the server hosting Checkmk as an example.

In the left sidebar, click Configuration | Agents. On the resulting page ( Figure B ), right click on check-mk-agent_2.0.0p9-1_all.dpkg and copy the address.

Figure B


Obtain the download link for installing the agent.

Go back to the terminal window and download the agent with:

wget URL

Where URL is the agent address you copied.

Install the agent with:

sudo dpkg -i check-mk-agent_2.0.0p9-1_all.dpkg

After installing the agent, go back to the Checkmk site and click Settings | Host, then click Add Host. On the resulting page ( Figure C ), you will need to enter the host name of the host to add and then click the checkbox for the IPv4 address.

Figure C


Adding a host to Checkmk.

Click Save and go to the service configuration. Eventually, this new page will list all the services found ( Figure D ).

Figure D


Checkmk has connected to the host and is listing the detected services.

If any services are listed as Undecided, click Fix All to fix the problem.

At this point, Checkmk is not monitoring the server it is hosted on. You can now go back to the dashboard and start customizing it to see what you need for that host. You can also continue to add agents to other servers and then add them as hosts on Checkmk.

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