I'm trying to access a natted secure ftp server using curl. I can get all the way in but when I try to upload a file I get:

< 425 Can't build data connection: Connection refused.
* Failed FTP upload: 425
* Uploaded unaligned file size (0 out of 15 bytes)
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- 0:00:03 --:--:-- 0* Closing connection #0
* SSLv3, TLS alert, Client hello (1):

curl: (25) Failed FTP upload: 425

The error 25 is "FTP couldn't STOR file. The server denied the STOR operation, used for FTP uploading." When I've asked the company I'm trying to upload this file to, they tell me that I wouldn't get this error if I was using a supported product. The problem is all the supported products are Windows based. Their only suggestion is that I use a put command instead of a stor command, even though they are the same thing. Does anyone have any thoughts on this or have a workaround?

No, 425 Error code as it said is : Can't open data connection. It is a network problem.

Mmmhhh (s)ftp are standard protocol, no need for a supported product ($$)

Put is the command understood by the interactive client program. It is then translated in "STOR" which is the FTP command. Eventhough I don't use curl, I don't think it is sending PUT on the socket!

1)Disable your firewall.
2)Try to switch from active / passive mode (add -P on the curl command line for active mode? -v for verbose mode will also help)
3)Try with (s)ftp
4)Try with winblows/"supported product"