Why is port 990 being used for implicit connection instead of port 21?

Giganews Newsgroups
Subject: Why is port 990 being used for implicit connection instead of port 21?
Posted by:  Michael J. Leaver (spam@mjleaver.com)
Date: Thu, 23 Jun 2005

If I tell an FTP server to use port 21 for implicit SSL/TLS connections,
and set the Port to 21 in TIdFTP, it fails to connect. Using TCPView
(from SysInternals) I see that an attempt is instead made to connect to
port 990, and not port 21. However, if I configure the FTP server, and
TIdFTP, to use port 991 for implicit SSL/TLS connections, it correctly
connects to port 991.

Why? I've not hard-coded my app to use port 990. Why does it get
redirected to port 990 when port 21 (and only 21) is used for implicit
SSL/TLS connections? Is something else redirecting it, or is Indy doing
this? I'm using Indy 10, Win XP Pro, and Delphi 7.

Thanks

Replies