Port scanner for your own server
Tries a list of common ports on a public server and shows which ones accept a connection. Private and loopback addresses (the ones used inside a home network, or by a computer to reach itself) are blocked.
Ports, and what open or closed means
A port is a numbered way in to a server. Each service waits behind its own number, a bit like flats that share one street address: websites use one port, email another, and proxies usually have theirs.
- Open: our server managed to connect on that port, so something is listening there and can be reached from the internet.
- Closed: we couldn't connect. The port might be shut, blocked by a firewall or too slow to answer, and this kind of scan can't tell which.
- Time: how long we waited on that port, in milliseconds.
- Which ports: a fixed list of common ones for websites, email, file transfer, DNS, remote access, databases and proxies. Ports outside the list aren't checked.
The scan runs from our server, so a firewall that only lets your own IP in will make ports look closed here even though they work for you. Setting up a proxy on your own server? This shows whether its port can be reached from outside.
Is this allowed? Only scan servers you own or have permission to test. Scanning someone else's systems can break their terms of service, or the law where you live.
