Kubernetes Cookbook - Second Edition

Proxy (kube-proxy)

The proxy handles the network proxy and load balancer for each container. It changes Linux iptables rules (nat table) to control TCP and UDP packets across the containers.

After starting the kube-proxy daemon, it configures iptables rules; you can use iptables -t nat -L or iptables -t nat -S to check the nat table rules, as follows:

//the result will be vary and dynamically changed by kube-proxy# sudo iptables -t nat -S-P PREROUTING ACCEPT-P INPUT ACCEPT-P OUTPUT ACCEPT-P POSTROUTING ACCEPT-N DOCKER-N FLANNEL-N KUBE-NODEPORT-CONTAINER-N KUBE-NODEPORT-HOST-N KUBE-PORTALS-CONTAINER-N KUBE-PORTALS-HOST-A PREROUTING -m comment --comment "handle ClusterIPs; NOTE: this must be before the NodePort rules" -j KUBE-PORTALS-CONTAINER ...