PORT 6443 / TCPInfrastructure & CloudExposure Risk: High

Port 6443: Kubernetes API — Kubernetes Control Plane API Server

HTTPS endpoint for kubectl and cluster communication with the Kubernetes kube-apiserver.

Default Service

Kubernetes API

Process: kube-apiserver

Transport Protocol

TCP

IANA Registered Port 6443

Docker Port Flag

-p 6443:6443

Container to Host Mapping

How to Check & Kill Process on Port 6443 (EADDRINUSE Fix)

macOS & Linux (lsof / kill)

# Find process using port 6443
sudo lsof -i :6443

# Instantly kill process on port 6443
lsof -ti:6443 | xargs kill -9

Windows (PowerShell & CMD)

# Find PID listening on port 6443
netstat -ano | findstr :6443

# Force kill by PID
taskkill /PID <PID_NUMBER> /F

Cross-Platform Node.js One-Liner

# Kill port 6443 via npx
npx kill-port 6443

# Or diagnose via Castov CLI
npx castov fix "EADDRINUSE :::6443"

Linux Firewall (UFW) & Connectivity Test

# Test if port 6443 is reachable
nc -zv localhost 6443

# Allow or deny port 6443 in UFW
sudo ufw allow 6443/tcp

Frequently Asked Questions about Port 6443

What is Port 6443 used for?

Port 6443 is the standard network port for Kubernetes API (Kubernetes Control Plane API Server) operating over TCP. The typical system daemon or process is kube-apiserver.

How do I kill a process running on Port 6443 (EADDRINUSE)?

On macOS and Linux, run: lsof -ti:6443 | xargs kill -9 (or npx kill-port 6443). On Windows PowerShell/CMD, run: netstat -ano | findstr :6443 and then taskkill /PID <PID> /F.