How to Check if a Port Number is Already in Use

This manual is in pilot operation.

Although the installer automatically checks if the port number is in use during installation, you can also verify this using the netstat command in Windows.

  1. From the Windows Start menu, select Run…​®…​.

  2. In the dialog box that appears, enter cmd in the "Open" field, and click the OK button.

  3. A DOS prompt (command input screen) will appear. Type the following and press ENTER:

    netstat -an

For detailed usage of the command, search on the internet or type netstat /? in the command prompt to display the explanation.

Netstat displays the "Local Address" field, where the IP address and port number are separated by a colon (for example,

Multiple IP addresses will be displayed. The types of displayed IP addresses are as follows:

IP Address
(Below are IPv6 addresses ⚠)

This is not an actual IP address assigned to this computer. If there is an application waiting for connections to any IP address assigned to this computer (see "Others" below), netstat displays the IP address as, followed by the port number it is waiting on.

fusion_place also waits for connections to any IP address, so and so on will be displayed in the Local Address field.

Called the "Local Loopback Address," it is a special address that always refers to "this computer."


These are the "actual" IP addresses assigned to this computer. Usually, there is only one, but if multiple network boards are installed in the computer, different IP addresses are assigned to each board, so multiple IP addresses will be displayed.

⚠ IP addresses enclosed in [] may also appear (e.g., [::], [::1]). These are addresses for IPv6, an extended version of IP. Currently, not many organizations use IPv6, so the above explanation is mainly based on the current IP (IPv4).

If a port number used by any of the above IP addresses is not installed with fusion_place, please avoid using it for fusion_place.