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DNS does not work with Weave CNI and Firewalld on RHEL 8 based OSs

This document (000020713) is provided subject to the disclaimer at the end of this document.

Environment

Firewalld service blocks Rancher cluster DNS on Rhel8.

Steps to reproduce:
     1. Install and setup RKE on RHEL 8
     2. CoreDNS is deployed as part of the RKE setup
     3. Start firewalld service on RHEL8 nodes.

After starting firewalld service, k8s pod logs return connection error:

ent-041273.voicelab.local. A: read udp 172.21.0.19:58953->1.10.64.26:53: i/o timeout --------------

Situation

The Internal Kubernetes DNS server (coredns) is blocked. Once firewalld is stopped, the Kubernetes DNS works.

Firewalld blocks these ports that are required:

- 2379-2380/tcp
- 4789/udp
- 5000/tcp
- 6443/tcp
- 6783/tcp
- 6783-6784/udp
- 9100/tcp
- 10250/tcp
- 10257/tcp
- 10259/tcp

Resolution

Stop firewalld on RHEL8 nodes, per requirements described in Rancher requirements.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:000020713
  • Creation Date: 27-Jul-2022
  • Modified Date:02-Apr-2025
    • SUSE Rancher

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