🔌 Port Scan
A Port Scan checks which network ports on a host are open, closed or filtered. Ports are numbered endpoints (0–65535) that services listen on — for example port 80 for web traffic, 443 for HTTPS, 22 for SSH.
What it does
A Port Scan checks which network ports on a host are open, closed or filtered. Ports are numbered endpoints (0–65535) that services listen on — for example port 80 for web traffic, 443 for HTTPS, 22 for SSH.
How to use it
Enter a hostname or IP and a range of ports to test. The scanner attempts a connection to each port and reports its state. Open ports indicate a service is listening; closed ports refuse the connection; filtered ports give no response (usually blocked by a firewall).
Real-world example
Before exposing a new server, scan it to confirm only the intended ports are open — say 443 for HTTPS and 22 for SSH — and that risky ports like 23 (Telnet) or 3389 (RDP) are firewalled. This is a quick way to shrink your attack surface.
Frequently Asked Questions
Is running a port scan legal?
Scanning your own systems or ones you are authorized to test is fine. Scanning networks you do not own can violate terms of service or local law, and many hosts interpret it as hostile reconnaissance.
What does 'filtered' mean?
A filtered result means the scanner received no reply — typically because a firewall is silently dropping the packets. It does not confirm whether a service exists behind the firewall.
Which ports should normally be open on a web server?
For a typical public website, ports 80 (HTTP, redirecting to HTTPS) and 443 (HTTPS) should be open. Administrative ports like 22 (SSH) are usually restricted to specific IPs rather than open to the world.