How to Use the PortQry Command Line Port Scanner When troubleshooting TCP/IP connectivity issues on Windows, standard tools like ping can be insufficient if firewalls block ICMP traffic. PortQry Command Line Port Scanner is a lightweight, standalone utility developed by Microsoft to report the state of local or remote TCP and UDP ports.
Unlike general-purpose utilities, PortQry provides detailed contextual data. For instance, when querying an Endpoint Mapper Database or Active Directory service, it interacts with the daemon to fetch active configuration parameters rather than just checking if the port responds. Understanding Port Status Reports
PortQry classifies network ports into three distinct statuses:
LISTENING: A target process is actively accepting traffic on the scanned port.
NOT LISTENING: The target system explicitly rejected the connection. This means it sent back an ICMP “Port Unreachable” message for UDP or a TCP packet with the RST (Reset) flag set.
FILTERED: The utility received no response at all. A dedicated security appliance, Windows Firewall, or network router is intentionally dropping or blocking the packets. Key Command Line Options
The syntax relies on a target destination followed by options to direct the scan: portqry.exe -n Use code with caution. Using the PortQry command-line tool – Windows Server
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