https://github.com/coreos/coreos-kubernetes/blob/master/Documentation/kubernetes-networking.md
*Master node(s):*
TCP 6443* Kubernetes API Server
TCP 10250 Kubelet API
TCP 10251 kube-scheduler
TCP 10252 kube-controller-manager
UDP 8285 flannel overlay network - udp backend
*Worker nodes (minions):*
TCP 10250 Kubelet API
TCP 30000-32767 NodePort Services
UDP 8285 flannel overlay network - udp backend