Port 6443 supports Kubernetes API server and sun-sr-https (UDP reference coverage) across distinct transports. Review each protocol before writing firewall or monitoring policy.
Default secure endpoint for the Kubernetes API server.
kubectl, controllers, nodes and integrations communicating with the cluster control plane.
Client to server
Enforce strong authentication, RBAC, audit logging and tightly scoped network access to the control plane.
sun-sr-https (UDP reference coverage) is documented as a network service convention for port 6443 over UDP.
Use this reference entry when identifying or validating systems documented to use 6443/UDP.
Varies
Confirm the listening process and current vendor documentation before permitting traffic; a listed convention does not prove the active service or its security posture.