You're welcome.
And no - I would not describe it as coming down to the active vs passive problem. Active vs passive is why you have been able to use other ftp servers on non-standard ports without difficulty - the lack of full support for passive ftp is one of the reasons you're having problems, the other is that your client side configuration does not support active ftp on a non-standard port - you need one or the other.
For what it's worth - I don't own and have never used a DNS-321, but if I had told you that earlier, you'd just have shot me down, on the basis that because I'd never used one, I didn't know what I was talking about. I have the DNS-323 (which uses essentially the same code), and have run the ftp server in the DNS-323, both on port 21 as well as non standard ports (more to prove that it could be done, than because of a need to), and have also been running ftp servers on other platforms for the better part of a decade.
Last, but by no means least, ftp on port 21 is not as much of a risk as people would have you believe - the big problem is that the username & password are transferred in clear text, and anyone who can connect a sniffer in the appropriate place can capture these credentials - BUT - that sniffer would have to be located in very specific places - the LAN on which the ftp server resides and the ISP's network that feeds that LAN, and the same two locations for the ftp client. As you move further away from those locations the volume of traffic that would have to be filtered to trap the credentials increases exponentially.
During 2008 I ran an unsecured (as in anonymous, and no password required) ftp server on port 21 for over six months before I logged a single "unauthorised" attempt at access. Given the furore about ftp insecurity, I would not have thought it possible, I expected it to be discovered long before it was.
Author
Topic: DNS-321 the FTP and port 21. Only option??? (Read 24041 times)