Checkmk Community (formerly Raw Edition)

Checkmk Community is the free, open-source edition of the Checkmk infrastructure monitoring platform, used by sysadmins to watch servers, network devices, applications and services from one web interface. Until version 2.4 it was called Checkmk Raw Edition; anyone searching for “Checkmk Raw Edition download” now gets the same software under the Community name, released under GPL-2.0 by Checkmk GmbH (formerly tribe29).

The rename is more than cosmetic. Since 2.5 the identifiers raw and cre became community, packages are named check-mk-community-… and the Docker image is checkmk/check-mk-community, so scripts and automation that reference the old names need updating. Community runs on the Nagios core with Checkmk’s rule-based configuration, auto-discovery and over 2,000 check plug-ins on top.

Checkmk Community at a glance

What it does

• Monitors Linux, Windows and Unix hosts through the Checkmk agent (TCP 6556), plus SNMP devices, HTTP endpoints and special agents for APIs.
• Service discovery finds file systems, interfaces, services and processes automatically and suggests checks with sensible thresholds.
• Rule-based configuration: set a threshold once for a folder or host tag instead of editing every host.
• Performance graphs, availability views, dashboards and a views/filters system in the web UI.
• Notifications by email and other methods with rules for who gets what and when.
• Manages multiple sites on one server with OMD (omd create, omd start, omd update).
• REST API for automation of hosts, folders and rules.

How sysadmins use it

Try it in Docker in five minutes

docker container run -dit 
  --name monitoring 
  -e CMK_PASSWORD='ChangeThisPassword' 
  -e TZ='Europe/London' 
  -v monitoring:/omd/sites 
  --tmpfs /opt/omd/sites/cmk/tmp:uid=1000,gid=1000 
  -p 8080:5000 -p 8000:8000 
  --restart always 
  checkmk/check-mk-community:2.5.0-latest

Open http://<docker-host>:8080/cmk/check_mk/ and log in as cmkadmin with the password from CMK_PASSWORD. Port 8000 is the agent receiver used when agents register for TLS.

Install on Ubuntu or Debian

1. Download the package for your distribution release from the official download page and verify its signature:

wget https://download.checkmk.com/checkmk/Check_MK-pubkey.gpg
gpg --import Check_MK-pubkey.gpg
gpg --verify /tmp/check-mk-community-2.5.0p14_0.jammy_amd64.deb
sudo apt install /tmp/check-mk-community-2.5.0p14_0.jammy_amd64.deb

2. Create and start a site:

sudo omd create --admin-password 'ChangeThisPassword' mysite
sudo omd start mysite
sudo omd status mysite

3. Browse to http://<server>/mysite and sign in as cmkadmin.

Add a Windows server

1. In the web UI, open Setup > Agents > Windows and get the MSI agent package for this version.
2. Install it on the server (an elevated install, or deploy the MSI with your software distribution tool).
3. Allow inbound TCP 6556 on the Windows server from the Checkmk server only.
4. Optionally register the agent controller for TLS-encrypted transport with cmk-agent-ctl register, pointing it at your Checkmk server and site.
5. In Setup > Hosts, add the host, save and run service discovery, accept the found services and activate the pending changes.

Get email notifications working

1. Configure the server’s local mail system (for example Postfix with a smarthost) so that the site user can send mail; Checkmk hands notifications to it.
2. Give each user an email address in their profile and add them to the right contact groups.
3. Review the notification rules under Setup > Events > Notifications and send a test notification.

Install and first run

• Server OS: Linux only. Packages exist for current Debian, Ubuntu LTS, Red Hat and SLES releases; check the download page for the exact list for 2.5. Use Docker or the virtual appliance on other systems.
• Windows and macOS: they cannot host the Checkmk server; they are monitored through agents.
• Ports: the web UI runs on 80/443 (or 5000 inside Docker), the agent on 6556, and agent registration on the agent receiver port (8000 in the Docker example).
• Updates: install the new package next to the old one and run omd update for the site. Move one major version at a time and read the incompatible changes (“werks”) before major upgrades.
• Sizing: the vendor positions Community for smaller environments of roughly up to 100 hosts; there is no hard limit, but the Nagios core is less efficient than the commercial core at scale.

Limitations

• Nagios core instead of the Checkmk Micro Core used in the commercial editions, which costs CPU at larger scale.
• No agent bakery: agents and their plug-ins are installed and updated with your own tooling.
• Reporting, advanced analytics, synthetic monitoring and some automation and distributed-monitoring features are reserved for Checkmk Pro and Ultimate.
• Community support only (forum and documentation).
• Rule-based configuration is powerful but takes time to learn, especially if you come from template-based tools.

Checkmk Community vs alternatives

FAQ

Is Checkmk free?

Checkmk Community (formerly Raw Edition) is free and open source under GPL-2.0. Checkmk Pro, Ultimate and Ultimate with Multi-Tenancy are commercial editions.

What happened to Checkmk Raw Edition?

It was renamed Checkmk Community. Versions 2.3 and 2.4 changed only the product title; 2.5 also renamed packages, identifiers and the Docker image.

What is the default Checkmk login?

The admin user is cmkadmin. Its password is the one you set with omd create --admin-password or CMK_PASSWORD in Docker; otherwise omd create prints a generated one.

Checkmk Raw vs Enterprise: what is the difference?

The commercial editions (Enterprise is now called Pro) add the Checkmk Micro Core, the agent bakery, reporting and more automation; Community uses Nagios and keeps the core monitoring features.

Can Checkmk run on Windows?

Not as a server. Run it on Linux, in Docker or as a virtual appliance, and monitor Windows hosts with the Windows agent.

Checkmk vs Nagios: which should I choose?

Checkmk Community uses a Nagios core but adds auto-discovery, rule-based configuration and a modern web UI, so it is far less manual than plain Nagios Core.

Is Checkmk on GitHub?

Yes, the source code is published in the Checkmk/checkmk repository on GitHub.

Last checked against official sources: 1 October 2026 (developer website: checkmk.com). Versions and licence terms change — confirm on the developer's site before deploying in production.