PORT 143 / TCPEmail & MessagingExposure Risk: Medium

Port 143: IMAP — Internet Message Access Protocol

Retrieves and syncs email messages across multiple devices. Use IMAPS (Port 993) for TLS encryption.

Default Service

IMAP

Process: dovecot

Transport Protocol

TCP

IANA Registered Port 143

Docker Port Flag

-p 143:143

Container to Host Mapping

How to Check & Kill Process on Port 143 (EADDRINUSE Fix)

macOS & Linux (lsof / kill)

# Find process using port 143
sudo lsof -i :143

# Instantly kill process on port 143
lsof -ti:143 | xargs kill -9

Windows (PowerShell & CMD)

# Find PID listening on port 143
netstat -ano | findstr :143

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

Cross-Platform Node.js One-Liner

# Kill port 143 via npx
npx kill-port 143

# Or diagnose via Castov CLI
npx castov fix "EADDRINUSE :::143"

Linux Firewall (UFW) & Connectivity Test

# Test if port 143 is reachable
nc -zv localhost 143

# Allow or deny port 143 in UFW
sudo ufw allow 143/tcp

Frequently Asked Questions about Port 143

What is Port 143 used for?

Port 143 is the standard network port for IMAP (Internet Message Access Protocol) operating over TCP. The typical system daemon or process is dovecot.

How do I kill a process running on Port 143 (EADDRINUSE)?

On macOS and Linux, run: lsof -ti:143 | xargs kill -9 (or npx kill-port 143). On Windows PowerShell/CMD, run: netstat -ano | findstr :143 and then taskkill /PID <PID> /F.