IE

Internet Explorer behaves as a Standard mode FTP client if you select the Enable folder view for FTP sites check box, even if you also select the Use Passive FTP check box.

If you clear the Enable folder view for FTP sites check box and then select the Use Passive FTP check box, Internet Explorer behaves as a Passive mode FTP client.

Internet Explorer 5.5 and later supports both Active and Passive FTP.

I prefer using Windows Explorer to access FTP site.

IIS FTP

The IIS-based FTP service (MSFTPSVC) supports both active and passive mode connections, depending on the method that is specified by the client.

Configuring IIS FTP for passive-mode connections--PassivePortRange

For performance reasons, the port range should be at least two times the number of anticipated concurrent file transfers.

Windows command line:

adsutil.vbs set /MSFTPSVC/PassivePortRange "5200-5600"

The firewall in front of the IIS server must have all the ports between 5200-5600 open.

FTP is a TCP based service exclusively.

Active FTP and Firewall

Server side: open port 21 and assigned PassivePortRange, e.g. 5200-5600.

Client side: none

Client side: open all ports above 1023

Passive FTP and Firewall

Server side: open port 21 and the