Port 3389 (TCP/UDP) — RDP

Check if port 3389 is open

On the server, see what is listening:

sudo ss -tulpn | grep ':3389 '

From another machine, test reachability:

nc -zv your-server.example.com 3389

Block port 3389 from the internet

With UFW (Ubuntu/Debian):

sudo ufw deny 3389

With firewalld (RHEL/AlmaLinux/Rocky):

sudo firewall-cmd --permanent --remove-port=3389/tcp && sudo firewall-cmd --reload

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