Optimizing Checkmk Performance: When to Disable the Agent Receiver

In Checkmk version 2.1 and newer, the Agent Receiver (listening on Port 8000) is a core process responsible for managing the Agent Controller. It handles the secure registration, TLS encryption, and the "Push" mode functionality of modern agents.

However, if you are running a lean environment or monitoring older infrastructure, you might find that you don't need these modern overheads.

The Case for "Legacy Mode" While the Agent Receiver is a powerful tool for security, it does consume system resources (CPU and Memory). If you are looking to squeeze every bit of performance out of your Checkmk server, you can revert to Legacy Pull Mode.

In this mode, the server connects directly to the monitored host via Port 6556 to retrieve plain-text data, bypassing the need for the Receiver entirely.

Warning: Disabling the Agent Receiver means you will lose TLS encryption for your monitoring data and the ability to use "Push" agents. Ensure your network is trusted before making this change.

To switch to Legacy Mode and free up system resources, follow these steps to update your site configuration:

1. Check the setting of Agent Receiver before make change.

omd config show | grep AGENT_RECEIVER

2. Stop your Checkmk site.

omd stop

3. Change the Receiver setting to off.

omd config set AGENT_RECEIVER off

4. Restart site to apply the changes.

omd start

5. Verification.

omd status