Check which TCP ports are open on any host. Use common presets or scan a custom list. Fast server-side scanning with service name identification.
What it checks: which TCP ports respond as open on a given host, with automatic service identification (e.g. 22 = SSH, 443 = HTTPS) — useful for verifying a firewall rule took effect or spotting an accidentally exposed service.
A port scanner checks which TCP ports are open on a host by attempting to connect to each one. Open ports indicate running services — for example, port 80 for HTTP, 443 for HTTPS, 22 for SSH, and 3306 for MySQL. Knowing which ports are open helps with network debugging and security auditing.
An open port means a service is actively listening and accepting connections. A closed port means the host is reachable but no service is listening on that port. A filtered port means a firewall is blocking the connection attempt — the host doesn't respond at all, causing a timeout.
It is legal and normal to scan ports on servers you own or have explicit permission to test. Scanning third-party servers without permission may be illegal in many jurisdictions. Our tool is designed for developers to test their own infrastructure.
Filtered ports are blocked by a firewall — typically a cloud provider security group (AWS, DigitalOcean, etc.) or a server-level firewall (ufw, iptables). Connection attempts time out instead of being refused. This is normal and expected for ports you intentionally block.