PASV (Passive) command
Defined in RFC 959, ôFile Transfer Protocol (FTP)ö at http://www.cis.ohio-state.edu/htbin/rfc/rfc959.html this command requests the server-DTP to ôlistenö on a data port (which is not its default data port) and to wait for a
connection rather than initiate one upon receipt of a transfer command. The response
to this command includes the host and port address this server is listening on.