To capture the data, launch Wireshark and click Capture > Interfaces to open a capture dialog. Start a capture on the interface with the netcat traffic. As soon as the capture begins, run the netcat command and then stop the capture.
Data Flow shows the data flow through the network during such a connection (Vista Enterprise, June 2007):
The hexadecimal data can be exported to a text file for trimming off the packet header, unneeded or variable parts and spaces. The relevant portion here is Microsoft… reserved. You can use the Wireshark hexadecimal payload export capability for this. For information about Wireshark, see Wireshark.