Port Scanner
Free online port scanner: use real TCP connect probes to find which ports are open on any host.
What is a TCP connect scan?
The scanner completes a full TCP handshake with each port. A successful handshake means the port is open; a refusal or timeout means it is closed or filtered.
What is the difference between closed and filtered?
A closed port actively refuses the connection; a filtered port silently drops packets (usually a firewall), which looks identical to a timeout from the outside.
Is port scanning legal?
Scanning your own host is fine anywhere. Scanning a third party may violate their terms of service — only scan systems you are authorised to test.
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