Continuous Linux Server Monitoring

Monitor every server with a single tool, regardless of distribution and location.

Monitor every Linux server everywhere

It is no surprise that almost every company uses Linux servers. With its focus on security, consistency and flexibility, Linux is predestined as an operating system for servers. The selection of distributions is huge and continues to grow.

IT admins most often use operating systems such as Red Hat Enterprise Linux (RHEL), CentOS, Fedora, openSUSE, Suse Linux Enterprise Server (SLES), Debian or Ubuntu, but depending on the use case, other systems can also be found on servers.

Similarly to the Linux distributions, there are completely free tools for monitoring – sometimes however, it makes sense to switch to professional solutions. The Checkmk Raw Edition is free to use and is completely open source.

We also offer an Enterprise Edition with additional features especially for use in business environments. Every Linux distribution is supported by the Checkmk agents. It does not matter whether the server is set up in the cloud, virtualised or on-prem. Checkmk recommends monitoring Linux servers via Checkmk agents, but also it supports monitoring via SNMP or IPMI.

The Checkmk agents support every Linux distribution. It doesn't matter whether you have set up your server in the cloud, virtualised or on-premises.

I honestly don’t know of a better monitoring solution for huge number of servers. This thing scales insanely, notifications are customisable, and there are integrations for every tool we use – Slack, Pagerduty, Mail...

Essential points for monitoring Linux servers with Checkmk

Running guy

A powerful lightweight

The Checkmk agents are only a few kilobytes in size, work in read-only mode, and can be managed centrally after installation.

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Flexible monitoring

There are over 1,900 plug-ins available. Monitor via agents, SNMP, or directly over APIs from vendors.

Hybrid Cloud icon

Hybrid monitoring

Monitor virtual servers, containers, cloud environments and distributed server landscapes with just a single platform.

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Easy setup and operation

With Checkmk you can set up your monitoring in a few minutes. Detailed documentation and tutorials are available.

The basics of Linux monitoring

Linux server monitoring witch Checkmk enables you to monitor different server types

Companies have to systematically monitor their Linux servers. That means checking status, metrics, logs and events at fixed intervals. Many distributions include functions such as ‘top’ – and these are available via the console. In practice, however, the command line is not suitable for monitoring server landscapes, as the effort for IT admins would not be justifiable.

As a result, numerous infrastructure monitoring tools have been developed that make monitoring more efficient. The most important basis when choosing a tool is the ability to monitor any server efficiently. Manual workarounds or queries for individual exceptions are not suitable.

Checkmk recommends monitoring via agents as the first option, since in this way Linux systems can be monitored in a particularly resource-saving manner. The Checkmk agent for Linux comes as a shell script, and it provides the data for monitoring via xinetd or systemd at TCP port 6556. Checkmk collects the information there and transfers it to the monitoring.

The agent is only a few kilobytes small. No files are compiled, and all processes are completely transparent at all times. The agent works in read-only mode and supports SSH. You will quickly be able write your own plug-ins. Checkmk can work with any output that meets its requirements.

If installing agents is not an option, Checkmk also supports agentless monitoring via SNMP or IPMI. There are also integrations in virtualisation platforms, manufacturer-supplied interfaces, and APIs from cloud providers.

Live Webinar: Introduction to Checkmk

Live Webinar: Introduction to Checkmk

Linux monitoring in day-to-day business

Linux is becoming an everyday part of IT, and is no longer used only by developers and IT admins. Monitoring solutions must therefore also be usable for specialists without extensive experience of using monitoring tools.

Checkmk is easy to install, and its administration takes place entirely via the Graphical User Interface (GUI). You can tailor metrics and analyses to the needs of specialist and IT experts using integrated graphing, dashboarding and reporting engines. In addition, integrations in external tools such as Grafana are available.

Since monitoring is gaining relevance for more and more departments and areas, tools have to be developed further. Over the years Checkmk has matured into an extensive, all-in-one platform, and yet it has retained its classic Linux qualities: good documentation, lean and secure architecture, expansion options and stable performance.

Screenshot server utilization in Checkmk

At the same time, however, it places great value on a high degree of user friendliness. Historically, Checkmk started as a Nagios fork, but for many years it has been a completely independent product. The Checkmk Raw Edition Edition still uses the Nagios core for monitoring.

The Enterprise Edition, on the other hand, uses the Checkmk Micro Core, and is therefore a completely independent development. Nevertheless, all Nagios plug-ins can also be integrated into Checkmk.

Start your monitoring with our Free Edition

Start your monitoring with our Free Edition

Implementation and cost-effectiveness of monitoring

The Checkmk instance itself is usually set up as a Linux server and is ready to start in a few minutes. Deployment is currently possible on SLES, RHEL, CentOS, Debian and Ubuntu. After downloading the corresponding package, you can start right away. No configuration of a database or other steps is required.

Checkmk is also available as a Docker container and appliance so that Checkmk can be used even without a Linux system.

Checkmk provides thresholds for the monitoring, and offers numerous features for the automatic integration of systems. This means less work for IT departments. Checkmk is also suitable for monitoring distributed environments and is readily scalable.

There are already over 1,900 official plug-ins, and their use is free of charge. A comprehensive manual and video tutorials are available to help get you started. In addition, everyone can share feedback or questions in the Checkmk Community Forum.

Checkmk also makes the Exchange available free of charge – there users can share, review and rate extensions they have written themselves.

On-demand Webinar: Introduction to Checkmk

On-demand Webinar: Introduction to Checkmk

Server migration with Linux

Requirements for IT infrastructures are changing, and accordingly it makes sense to evaluate your own server systems again and again. A migration to Linux or another distribution/platform (such as a cloud or virtualised server) is therefore almost a part of everyday life.

However, this must not have any undesired consequences for monitoring. Regardless of whether you use Red Hat Enterprise Linux (RHEL), CentOS, Fedora, Debian, OpenSUSE, SUSE Linux Enterprise Server (SLES) or another distribution – with Checkmk you have everything on screen.

In just a few minutes after installation Checkmk will provide you with a deep insight and visibility into your systems and applications.

Checkmk server monitoring comprehensively supports heterogeneous server landscapes that use Windows, MacOS, Linux servers, or other systems. Relocations of servers from campus to the cloud, or the replacement of bare-metal servers by virtual machines can also be represented in the monitoring. Read more about the monitoring of different server types and what server monitoring is.

Screenshot server monitoring dashboard

Integrations for Checkmk are available in all common virtualisation solutions, so that not only virtual servers, but also the monitoring of their platforms such as VMWare ESXi or Microsoft Hyper-V is possible.

Agents are also not a requirement for monitoring. Checkmk has integrations for almost all common protocols (such as SNMP), APIs and interfaces (e.g. IPMI), and is in no way limited to agents.

Understanding the special requirements of Linux servers

Linux penguin

Linux servers are considered robust, but an operating system alone does not protect against problems or configuration errors. You should of course follow the general rules for server monitoring.

Experience has also shown that Linux itself has its own mechanisms to improve server performance. This should be considered when monitoring. For example, there is a relationship between RAM and SWAP that is relevant for monitoring. By default, you often only look at the RAM.

Memory management does not work according to the overflow principle, however Linux is intelligent enough to take the size of application processes into account, and it therefore pushes processes into a SWAP before the RAM is full. An alert for (almost) full memory is therefore not practical.

You can read more about memory monitoring under linux on our blog.


Inventory of Linux servers

Server infrastructure is now part of a delivery chain for applications and services. Causal relationships which go beyond system monitoring must therefore be recognisable in professional monitoring.

It is also important to be able to check the functioning of components and software, for example a corresponding inventory allows the recognition of all installed components and installed software. In this way, changed or broken components can be identified, for example.

A hardware defect on a partition, for example, only becomes apparent when you look at its metrics over time. For the Linux system, on the other hand, the hard disk seems to have space. When trying to write, however, data is lost.

Thanks to Checkmk, we have a precise overview of the lifecycle and the use of our systems. This ability is a powerful decision-making aid when it comes to the entrepreneurial orientation of these systems.

Processing the information for a license management system is easy. This can prepare you for an audit, for example. Integrate the Checkmk HW/SW Inventory in your configuration management database (CMDB) to always have an up-to-date overview of your IT.

Screenshot server inventory in Checkmk

Start your monitoring with our Free Edition

Start your monitoring with our Free Edition

Linux server monitoring for Enterprises

Monitoring Linux servers in extensive IT landscapes is complex without the right tools, and can also swallow a lot of resources in the form of additional hardware.

The Checkmk Enterprise Edition provides numerous features from which companies can benefit in the long term. Checkmk’s own Micro Core reduces the hardware requirement, so that 100,000 or more hosts can be monitored in a single dashboard.

With the distributed Monitoring function, you manage different locations via a central Checkmk instance. Checkmk is therefore able to monitor even the most extensive environments. Manage agents easily with Checkmk’s own agent bakery. After a single installation on the server, the agent can be adapted and updated using Checkmk. Agents created with specific settings can be packaged and distributed as RPM or DEB.

Checkmk has everything you need to monitor server environments. It runs very stably, and so far we have had no real difficulties.

Various support levels and training courses are available on request. The Checkmk Forum is also open to all users. In addition, with the Checkmk Exchange we have provided a platform for sharing your own packages and extensions. And of course there are also events and meet-ups. Every year we also invite you to the Checkmk Conference, the world’s largest Checkmk user meeting.


Linux server monitoring FAQ

Yes – a Checkmk version is available as a Docker container and as an appliance, so you can also use Checkmk on other operating systems, too. The appliance can be deployed virtually or as physical hardware. This only applies to the Checkmk server itself. The actual monitoring supports any type of server, network device, storage, etc..

No way. The more containers and virtual machines running on a server, the more robust and stable it has to be. You should therefore monitor the server and the containers. Checkmk can perform a check every second and therefore recognises containers, even if they only exist for a short time. Detection, recording and removal are done automatically. Monitor servers and containers in one platform. This helps to identify and eliminate possible relations in the event of problems. Learn more about virtual server monitoring.

The hardware requirements are relatively low due to the Linux architecture and the many available agents, since compared to pure monitoring without agents – only via SNMP for example – fewer hardware resources are needed. For Linux servers in particular the agent consists of only one shell script, so the footprint is particularly small.

Various Linux distributions are suitable for setting up Checkmk, many of which are completely free, such as ClearOS Community or Ubuntu. In this case there are no additional costs. If you use commercial Linux distributions like RHEL, you need the corresponding licenses from the manufacturer.

Of course, Checkmk can monitor rented servers, and you can adjust alerts for compliance with SLAs. If, for example, the RAM provided falls below a minimum value, you will receive a message. If a service provider does not allow the installation of agents, Checkmk supports agentless monitoring via IPMI or SNMP.

Yes, a change is quite easy, and possible without any problems. You can get the Enterprise Edition from our homepage. The costs start at 600 Euros per year.

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Download the latest version of Checkmk Enterprise Free Edition today and see it in action.