Port 6443 (Kubernetes API) — What It Is and How to Use It

Port 6443 is the default secure port for the Kubernetes API server. It is the primary interface for all communication with the Kubernetes control plane, allowing users and components to manage clusters, deploy applications, and retrieve cluster state information.

Last updated: 2026-06-11

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                Port Number
                6443
            

Protocol Kubernetes API

Common Use Cases

kubectl commands to interact with the Kubernetes cluster (e.g., `kubectl get pods`, `kubectl apply -f deployment.yaml`)
Internal Kubernetes components (e.g., Kubelet, Kube-proxy, Controllers) communicating with the API server
External tools and integrations (e.g., CI/CD pipelines, monitoring systems) managing Kubernetes resources
Accessing the Kubernetes dashboard

Interactive Command Builder

Target Host / IP

Operating System

Generated Command

nc -zv example.com 6443

Check if Port 6443 is Open

Linux: `sudo ss -tlnp | grep 6443` or `sudo netstat -tlnp | grep 6443`

Windows: `netstat -ano | findstr :6443`

⚠️ Security Note: Due to its critical role, port 6443 must be secured with TLS/SSL and strong authentication/authorization mechanisms (e.g., RBAC). Unauthorized access to this port can lead to full compromise of the Kubernetes cluster.

Related Ports

Frequently Asked Questions

Is port 6443 dangerous to leave open?

Yes, if not properly secured. Leaving port 6443 open to the public internet without robust authentication, authorization (RBAC), and network policies is extremely dangerous and can lead to complete cluster compromise. It should ideally be restricted to trusted networks and clients.

What service uses port 6443?

The Kubernetes API server uses port 6443. This is the central component of the Kubernetes control plane that exposes the Kubernetes API.