PORT 80 / TCPWeb & HTTPExposure Risk: Medium

Port 80: HTTP — Hypertext Transfer Protocol (Unencrypted Web)

Default port for unencrypted web traffic. In modern production setups, Port 80 immediately redirects (HTTP 301) to HTTPS on Port 443.

Default Service

HTTP

Process: nginx / apache2 / caddy

Transport Protocol

TCP

IANA Registered Port 80

Docker Port Flag

-p 80:80

Container to Host Mapping

How to Check & Kill Process on Port 80 (EADDRINUSE Fix)

macOS & Linux (lsof / kill)

# Find process using port 80
sudo lsof -i :80

# Instantly kill process on port 80
lsof -ti:80 | xargs kill -9

Windows (PowerShell & CMD)

# Find PID listening on port 80
netstat -ano | findstr :80

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

Cross-Platform Node.js One-Liner

# Kill port 80 via npx
npx kill-port 80

# Or diagnose via Castov CLI
npx castov fix "EADDRINUSE :::80"

Linux Firewall (UFW) & Connectivity Test

# Test if port 80 is reachable
nc -zv localhost 80

# Allow or deny port 80 in UFW
sudo ufw allow 80/tcp

Frequently Asked Questions about Port 80

What is Port 80 used for?

Port 80 is the standard network port for HTTP (Hypertext Transfer Protocol (Unencrypted Web)) operating over TCP. The typical system daemon or process is nginx / apache2 / caddy.

How do I kill a process running on Port 80 (EADDRINUSE)?

On macOS and Linux, run: lsof -ti:80 | xargs kill -9 (or npx kill-port 80). On Windows PowerShell/CMD, run: netstat -ano | findstr :80 and then taskkill /PID <PID> /F.

Is it safe to expose Port 80 to the internet?

Port 80 has a Medium security risk profile. Default port for unencrypted web traffic. In modern production setups, Port 80 immediately redirects (HTTP 301) to HTTPS on Port 443.