Arduino and netcat

hello.
i am trying to use my arduino boards with netcat, but i know nothing of tcp/ip or udp, i’m just taking a bunch of stabs in the dark really.
is there a local port number that the board uses? setting /dev/cu.usbserial-181, which is the method for specifiying where to listen in processing for instance, doesn’t work in netcat.
any ideas??

will.