This is probably the easiest way to transfer files from your Android smartphone to your computer using netcat. Simply use the file explorer of your choice, select and share the files you want to transfer to your computer.
HOW TO: https://goo.gl/Mp2mLn
You must be in the same network as the target machine. Then enter IP and port of the nc server.
NetCatdroid will put all files into a TAR archive. Keep this in mind when you pipe nc into a file.
Netcat is installed by default on any Mac and Ubuntu.
Start server with
nc -l 4711 > files.tar