Ports and Protocols

When running Kubernetes in an environment with strict network boundaries, such as on-premises datacenter with physical network firewalls or Virtual Networks in Public Cloud, it is useful to be aware of the ports and protocols used by Kubernetes components.

Control plane

ProtocolDirectionPort RangePurposeUsed By
TCPInbound6443Kubernetes API serverAll
TCPInbound2379-2380etcd server client APIkube-apiserver, etcd
TCPInbound10250Kubelet APISelf, Control plane

Although etcd ports are included in control plane section, you can also host your own etcd cluster externally or on custom ports.

Worker node(s)

ProtocolDirectionPort RangePurposeUsed By
TCPInbound10250Kubelet APISelf, Control plane
TCPInbound10256kube-proxySelf, Load balancers
TCPInbound30000-32767NodePort Services†All

† Default port range for NodePort Services.

All default port numbers can be overridden. When custom ports are used those ports need to be open instead of defaults mentioned here.

One common example is API server port that is sometimes switched to 443. Alternatively, the default port is kept as is and API server is put behind a load balancer that listens on 443 and routes the requests to API server on the default port.

Last modified March 25, 2024 at 11:47 AM PST: Add kube-proxy healthz port to ports-and-protocols.md (d917d5020c)