Internet Direct (Indy) Version 9.0.2 Beta
TIdFTPServerThread.PASV
Inducates if the DataChannel should listen for client connections.

property PASV: Boolean;
Description
PASV is a Boolean property that indicates that the TIdFTPServerThread should listen on a non-standard DataPort for the FTP DataChannel connection. PASV is used in the command reply handler for the FTP PASV command to create and initialize the DataChannel for the Authenticated FTP connection, and starts listening for the Client connection on the DataChannel.

PASV is read in the RETR command reply handler to determine if the DataChannel should Connect (when Passive is False) or Listen for the client connection (when Passive is True) prior to transferring FTP data.