FTP Port mode, sometimes called Standard mode or Active mode, first establishes a connection to TCP port 21 on the FTP server. When the client needs to receive data, it sends a PORT command to the server, which opens a new connection to the client on TCP port 20.
FTP PASV mode clients, sometimes called Passive mode, also start by establishing a connection to TCP port 21 on the FTP server. When the client sends a PASV command, the server opens an ephemeral port (short lived port) between 1024 and 5000, and informs the client to use that port as the source port for the data transfer.
NOTE: Some FTP servers open an an ephemeral port between 1024 and 65536. If you are unable to connect to a TCP port above 5000, see tip 0914.
To change which mode that Internet Explorer uses:
1. Open Internet Explorer.
2. Press Internet Options on the Tools menu.
3. Select the Advanced tab.
4. To behave as a PORT mode client, the Enable folder view for FTP sites box should be checked.
NOTE When the Enable folder view for FTP sites box is checked, it does NOT matter if the Use Passive FTP box is checked.
5. To enable PASV mode, clear the Enable folder view for FTP sites box, and check the Use Passive FTP box.
6. Press Apply and OK.
NOTE: You must be aware of which ports your firewall blocks.