The port number the node used. If you wire 0 to the port input, LabVIEW dynamically chooses an available TCP port that the operating system determines is valid for use. If you wire a value other than zero to the input port, the output port number equals the input port number. As defined by the Internet Assigned Numbers Authority (IANA), valid port numbers are between the range of 49152 through 65535. Well-known ports range from 0 to 1023 and registered ports range from 1024 to 49151. However, not all operating systems follow the IANA standard. For example, Windows returns dynamic ports in the range from 1024 to 5000.