Unless you really know what you are doing, the easiest bet is to use existing higher-level protocols instead of just "sockets". For example, 10-15 lines of code with HTTP::Daemon will get you a server waiting for a request, and another 5-10 lines of code will let you use HTTP::Request::Common to POST your file to be transferred, even passing some authentication to verify the source of the transmission. Using raw sockets, you'd be hard-pressed to even get the socket open in that few lines.

-- Randal L. Schwartz, Perl hacker