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we currently have following Kubernetes setup (v1.13.1, setup with kubeadm) with connectivity set up between them:

  • Master node (bare metal)
  • 5 worker nodes (bare metal)
  • 2 worker nodes (cloud)
  • There is no proxy in between to access cluster, currently we are accessing services via hostname:NodePort

We are experiencing issue with accessing services via NodePort on 2 cloud worker nodes. What is happening is that service is accessible via IPv6, but not via IPv4:

  • IPv6: telnet localhost6 30005 Trying ::1... Connected to localhost6. Escape character is '^]'.
  • IPv4: telnet localhost4 30005 Trying 127.0.0.1...

Thing is that both are working on bare metal nodes. If I use netstat -napl | grep 30005, I can see kube-proxy is listening on this port (tcp6). I presumed this means that it does not listen on tcp, but aparently this is not the case (I have same picture on bare metal worker nodes):

tcp6       7      0 :::30005                :::*                    LISTEN      24658/kube-proxy

I have also read that services are using IPv6, but based on bare metal worker nodes, it seems there should not be a problem using IPv4 there as well.

Any idea what would cause that issue and how to solve it?

Thank you and best regards, Bostjan

Bostjan
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1 Answers1

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In case someone stumbles upon same issue, there was issue with unopened ports on FW for flannel network overlay:

  • 8285 UDP - flannel UDP backend
  • 8472 UDP - flannel vxlan backend
Bostjan
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