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C.7 What software uses what FTP mode?

  It is up to the client to decide what mode to use; the default mode when a new connection is opened is ``active mode''.

Most FTP clients come preconfigured to use active mode, but provide an option to use ``passive'' (``PASV'') mode. An exception is the windows command line FTP client which only operates in active mode.

Web Browsers generally use passive mode when connecting via FTP, with a weird exception: MSIE 5 will use active FTP when FTP:ing in ``File Explorer'' mode and passive FTP when FTP:ing in ``Web Page'' mode. There is no reason whatsoever for this behaviour; my guess is that someone in Redmond with no knowledge of FTP decided that ``Of course we'll use active mode when we're in file explorer mode, since that looks more active than a web page''. Go figure.

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