Port 11211 (Memcached)

What is Port 11211?

Port 11211 is the default port for Memcached, a high-performance distributed memory caching system. Memcached accelerates web applications by reducing database load through in-memory key-value caching.

Memcached on port 11211 accepts client connections for storing and retrieving cached data. It supports both TCP and UDP protocols, with simple text and binary protocols for get/set/delete operations. Memcached is used by major websites including Facebook, Wikipedia, and Twitter to cache database query results, API responses, and session data.

Memcached has no authentication and should never be exposed to the internet. Publicly accessible Memcached servers have been exploited for DDoS amplification attacks (up to 51,000x amplification factor). Bind to localhost, use firewalls, and disable UDP if not needed.

Port 11211 Security

Memcached on port 11211 should be secured with appropriate access controls and monitoring. Ensure the service is only accessible from trusted networks by configuring firewall rules to restrict access. If the protocol supports encryption, enable TLS/SSL to protect data in transit.

Regularly update Memcached to the latest version to patch known vulnerabilities. Monitor port 11211 for unauthorized access attempts and implement rate limiting where possible. Follow the principle of least privilege when configuring access permissions.

How to Check Port 11211

To check if port 11211 is open on a remote host, use nmap: 'nmap -p 11211 hostname'. For a quick TCP connection test, use: 'telnet hostname 11211' or 'nc -zv hostname 11211'. On Windows PowerShell, use: 'Test-NetConnection -ComputerName hostname -Port 11211'.

To check if port 11211 is listening on your local machine, use: 'netstat -tlnp | grep 11211' on Linux, or 'ss -tlnp | grep 11211'. On Windows, use: 'netstat -an | findstr 11211'. For a comprehensive scan, use: 'nmap -sV -p 11211 hostname' to detect the service version running on the port.

Related Ports

Frequently Asked Questions

What is port 11211 used for?

Port 11211 is the default port for Memcached Cache Server (Memcached). It is used for memcached communication using the BOTH protocol.

Is port 11211 TCP or UDP?

Port 11211 uses BOTH. TCP provides reliable, ordered delivery while UDP is faster but connectionless.

Should port 11211 be open?

Port 11211 should only be open if you are actively running Memcached. Close unused ports to reduce your attack surface. If needed, restrict access to trusted IP addresses using firewall rules.

How do I check if port 11211 is open?

Use 'nmap -p 11211 hostname' to scan remotely, or 'netstat -tlnp | grep 11211' to check locally on Linux. On Windows, use 'Test-NetConnection -Port 11211 hostname' in PowerShell.

How do I secure port 11211?

Secure port 11211 by restricting access with firewall rules, using encryption (TLS/SSL) where supported, keeping Memcached updated, using strong authentication, and monitoring for unauthorized access attempts.

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