Port 9090 (TCP) — Prometheus

Prometheus server web UI and API.

🔒 Runs locally — your input never leaves this browser tab

Exposes your whole metrics inventory. Add auth or keep private.

Check if port 9090 is open

On the server, see what is listening:

sudo ss -tulpn | grep ':9090 '

From another machine, test reachability:

nc -zv your-server.example.com 9090

With UFW (Ubuntu/Debian):

sudo ufw deny 9090

With firewalld (RHEL/AlmaLinux/Rocky):

sudo firewall-cmd --permanent --remove-port=9090/tcp && sudo firewall-cmd --reload