PORT 1433 / TCPDatabase & CacheExposure Risk: Critical

Port 1433: MS SQL Server — Microsoft SQL Server Database Engine

Default port for Microsoft SQL Server client connections. Restrict to private VPC subnets.

Default Service

MS SQL Server

Process: sqlservr

Transport Protocol

TCP

IANA Registered Port 1433

Docker Port Flag

-p 1433:1433

Container to Host Mapping

How to Check & Kill Process on Port 1433 (EADDRINUSE Fix)

macOS & Linux (lsof / kill)

# Find process using port 1433
sudo lsof -i :1433

# Instantly kill process on port 1433
lsof -ti:1433 | xargs kill -9

Windows (PowerShell & CMD)

# Find PID listening on port 1433
netstat -ano | findstr :1433

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

Cross-Platform Node.js One-Liner

# Kill port 1433 via npx
npx kill-port 1433

# Or diagnose via Castov CLI
npx castov fix "EADDRINUSE :::1433"

Linux Firewall (UFW) & Connectivity Test

# Test if port 1433 is reachable
nc -zv localhost 1433

# Allow or deny port 1433 in UFW
sudo ufw allow 1433/tcp

Frequently Asked Questions about Port 1433

What is Port 1433 used for?

Port 1433 is the standard network port for MS SQL Server (Microsoft SQL Server Database Engine) operating over TCP. The typical system daemon or process is sqlservr.

How do I kill a process running on Port 1433 (EADDRINUSE)?

On macOS and Linux, run: lsof -ti:1433 | xargs kill -9 (or npx kill-port 1433). On Windows PowerShell/CMD, run: netstat -ano | findstr :1433 and then taskkill /PID <PID> /F.