Port 11211 (TCP/UDP) — Memcached

Check if port 11211 is open

On the server, see what is listening:

sudo ss -tulpn | grep ':11211 '

From another machine, test reachability:

nc -zv your-server.example.com 11211

Block port 11211 from the internet

With UFW (Ubuntu/Debian):

sudo ufw deny 11211

With firewalld (RHEL/AlmaLinux/Rocky):

sudo firewall-cmd --permanent --remove-port=11211/tcp && sudo firewall-cmd --reload

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