Verify kubelet's certificate before establishing connection. Rationale: The connections from the apiserver to the kubelet are used for fetching logs for pods, attaching (through kubectl) to running pods, and using the kubelet's port-forwarding functionality. These connections terminate at the kubelet's HTTPS endpoint. By default, the apiserver does not verify the kubelet's serving certificate, which makes the connection subject to man-in-the-middle attacks, and unsafe to run over untrusted and/or public networks. Impact: You require TLS to be configured on apiserver as well as kubelets.
Follow the Kubernetes documentation and setup the TLS connection between the apiserver and kubelets. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --kubelet-certificate-authority parameter to the path to the cert file for the certificate authority. --kubelet-certificate-authority=<ca-string> Default Value: By default, --kubelet-certificate-authority argument is not set.