# host.sh: Port check

> Check which of 20 common TCP ports on your own IP address answer from the internet, tested from Cloudflare's network. Free, no sign-up, your address only.

The [port check](https://www.host.sh/ports) connects from Cloudflare's network to the address you visit from, and to your IPv4 address too when you have both. It can only check you, never another address, and it runs after a short browser check.

## What the results mean

| State | What it means |
|---|---|
| open | Something on your side accepted the connection. Make sure you meant to expose it |
| closed | Your router or computer refused the connection, or it failed right away |
| filtered | No answer in time, usually a firewall dropping it. This is the safest state |
| unknown | The check couldn't tell: every connection to the address failed at once, or the scan ran out of time |

## Limits

- TCP only: UDP services can't be checked this way, and port 25 (mail) is left out.
- Behind iCloud Private Relay, a VPN or a proxy, the check reaches that service, not you. Turn it off to test your own connection.
- If your connection leaves from more than one address, each one the check sees is tested.