For a start, my UDP_Funcs check the address and port number of
every packet sent, and discards it if it doesn't match up to a player
that's already logged on- this stops any person from grabbing my
UDP_Funcs and sending fake/destructive packets- they'd have to really
know what they were doing, as they'd have to send RAW packets (make
their own packets up with a fake header), to screw my routines over.
  Another (and the best) way, would be to use the Secure Sockets Layer
available in Miami.
  More stuff can be done to improve security obviously!