PORT 11211 / TCP/UDPDatabase & CacheExposure Risk: Critical

Port 11211: Memcached — Memcached Distributed Memory Caching

High-performance distributed memory object caching system. Must never be exposed on UDP to the public internet (DDoS amplification risk).

Default Service

Memcached

Process: memcached

Transport Protocol

TCP/UDP

IANA Registered Port 11211

Docker Port Flag

-p 11211:11211

Container to Host Mapping

How to Check & Kill Process on Port 11211 (EADDRINUSE Fix)

macOS & Linux (lsof / kill)

# Find process using port 11211
sudo lsof -i :11211

# Instantly kill process on port 11211
lsof -ti:11211 | xargs kill -9

Windows (PowerShell & CMD)

# Find PID listening on port 11211
netstat -ano | findstr :11211

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

Cross-Platform Node.js One-Liner

# Kill port 11211 via npx
npx kill-port 11211

# Or diagnose via Castov CLI
npx castov fix "EADDRINUSE :::11211"

Linux Firewall (UFW) & Connectivity Test

# Test if port 11211 is reachable
nc -zv localhost 11211

# Allow or deny port 11211 in UFW
sudo ufw allow 11211/tcp

Frequently Asked Questions about Port 11211

What is Port 11211 used for?

Port 11211 is the standard network port for Memcached (Memcached Distributed Memory Caching) operating over TCP/UDP. The typical system daemon or process is memcached.

How do I kill a process running on Port 11211 (EADDRINUSE)?

On macOS and Linux, run: lsof -ti:11211 | xargs kill -9 (or npx kill-port 11211). On Windows PowerShell/CMD, run: netstat -ano | findstr :11211 and then taskkill /PID <PID> /F.

Is it safe to expose Port 11211 to the internet?

Port 11211 has a Critical security risk profile. High-performance distributed memory object caching system. Must never be exposed on UDP to the public internet (DDoS amplification risk).