function onConnection( socket ) {
		var key = socket.remoteAddress + ':' + socket.remotePort;

		debug( 'Received a socket connection: %s.', key );
		connections[ key ] = socket;
		socket.on( 'close', onClose );

		/**
		* Callback invoked once a socket connection closes.
		*
		* @private
		*/
		function onClose() {
			debug( 'Socket connection closed: %s.', key );
			delete connections[ key ];
		}
	}
Callback invoked upon receiving a socket connection.

@private
@param {Socket} socket - socket connection