Network policies are Kubernetes resources that control the traffic between pods and/or network endpoints. The rules use labels to select pods and identify the traffic that is directed towards those pods. Network policy controller is responsible for reading the namespace, network policy and pods information from Kubernetes API server and configure netfilter (iptables) accordingly to provide ingress filter to the pods.
Most CNI plugins implement network policy controller, however, if they don’t and we create a
NetworkPolicy, then that resource will be ignored.