ncp (fast file copy tool for LANs)

"ncp" is a utility for copying files in a LAN. It has absolutely no
security or integrity checking, no throttling, no features, except
one: you don't have to type the coordinates of your peer.

Basically it works like this:

 1. You and your buddy want to play Quake.
 2. Your buddy has a level that you don't have.
 3. He types "npush filename" and waits. npush sends out UDP
    announcement packets proclaiming that someone wants to send
    something.
 4. You type "npoll". npoll waits until it sees one of these packets.
 5. The files are copied with tar over a TCP socket, so permissions and
    file dates (and if you are root, owners) are preserved.
