localhost:9443: what runs on it and how to open it
Port 9443 is the HTTPS web page of Portainer. How to open it and fix certificate warnings.
Open this address: http://localhost:9443This opens on your own computer. It only works if the program is running.
localhost:9443 is the HTTPS page of Portainer. Use https://, and create the admin user on the first visit. Mounting the Docker socket gives the container control over Docker, so keep the page private.
What runs on localhost:9443
- Portainer, a web page for managing Docker
Commands to start and test port 9443
docker run -d -p 9443:9443 -v /var/run/docker.sock:/var/run/docker.sock -v portainer_data:/data portainer/portainer-cecurl -k https://localhost:9443Find what is using port 9443
Run these in a terminal on your computer. Nothing is sent to this site.
If localhost:9443 will not open
- The browser warns about the certificate
- Portainer starts with a self-signed certificate. On your own machine you can continue.
- Setup timed out
- Portainer asks you to create the admin user within a few minutes after the first start. Restart the container and try again.
- Port 9443 is already in use
- Another program is on this port. Find it with the tool below and stop it, or start yours on another port.
- This site can’t be reached (ERR_CONNECTION_REFUSED)
- The program is not running. Start it and keep that terminal open. See the full checklist.
- Works on your computer, not on your phone
- Start the server on all network addresses and use your computer’s IP address. See how to open localhost from your phone.
Other ports like 9443
| Port | Usually used by |
|---|---|
| localhost:11434 | Ollama (AI models) |
| localhost:5601 | Kibana |
| localhost:11501 | Not a standard port: check what is using it |
| localhost:9200 | Elasticsearch |
| localhost:5672 | RabbitMQ |
| localhost:15672 | RabbitMQ admin page |
| localhost:9090 | Prometheus |
Questions about localhost:9443
- Why is the Docker socket mounted?
- So Portainer can manage your containers. It also means anyone who gets into Portainer controls Docker.
- Is localhost:9443 safe?
- Yes, as long as it stays on localhost. Only your own computer can reach it. It becomes reachable from other devices only if you start the program on 0.0.0.0 or your computer's IP address. Do not put development or admin tools on the public internet.
- Can I use a different port instead of 9443?
- Yes. Most programs let you choose the port with a setting or a command option. Pick a free port above 1024 and open that number instead.
- How do I check what is using port 9443?
- Use the port checker on this page. It shows the command for Windows, macOS and Linux and does not send anything to this site.
- Can I open localhost:9443 from my phone?
- Yes, if both are on the same Wi-Fi. Start the program so it listens on all addresses, then open your computer's IP address with the port on the phone. A firewall on the computer can still block it.
Free tools that help
- Common ports listSearch a list of common TCP and UDP port numbers: SSH 22, HTTP 80, HTTPS 443, MySQL 3306, PostgreSQL 5432 and more, with dev server ports.