What port does Prometheus use?
Prometheus uses port 9090 over TCP.
| Port | Protocol | Name | What it is for |
|---|---|---|---|
| 9090 | TCP | Prometheus | The Prometheus metrics server and web UI. |
Exposing it
Prometheus has no authentication of its own. Put it behind a reverse proxy that does.
Checking it is listening
sudo lsof -i :9090 # macOS, Linux
netstat -ano | findstr :9090 # Windows
nc -zv host 9090 # from elsewhereAn "address already in use" error on a port nothing appears to be holding usually means the socket is in TIME_WAIT rather than that a process has it — the ports reference covers that and the ephemeral range.
Frequently asked questions
What port does Prometheus use?
Prometheus uses port 9090 over TCP. The Prometheus metrics server and web UI.
Is port 9090 safe to expose to the internet?
Prometheus has no authentication of its own. Put it behind a reverse proxy that does.
How do I check whether Prometheus is listening?
sudo lsof -i :9090 on macOS or Linux, netstat -ano | findstr :9090 on Windows. From another machine, nc -zv host 9090 says whether anything answers.