Ok, I tried it with FieZilla
Unfortunatelly I got the same result: with the last version 3.5.3 didn't work. Then I tried 3.5.2 and it worked. I look for the error message:
GnuTLS alert 40: Handshake failed
And found this:
https://forum.filezilla-project.org/viewtopic.php?t=23280
In deed it seems to be a dropped feauture in SSL. According to my log file, the NAS Server I have uses vsftd. The solution given in the previous thread, implies to modify the configuration from the ftp server; however, I can't do it because it is a built-in server.
I will write Seagate about the problem.
Thanks
Josef
Just for the interested, this is the log file from FileZilla:
2012-06-28 08:50:49 8556 3 Status: Resolving address of xxxxxxxxxxxxxxxx
2012-06-28 08:50:49 8556 3 Status: Connecting to xxx.xxx.xxx.xxx:21...
2012-06-28 08:50:49 8556 3 Status: Connection established, waiting for welcome message...
2012-06-28 08:50:49 8556 3 Trace: CFtpControlSocket::OnReceive()
2012-06-28 08:50:49 8556 3 Response: 220 vsFTPd 2.0.7+ (ext.1) ready...
2012-06-28 08:50:49 8556 3 Trace: CFtpControlSocket::SendNextCommand()
2012-06-28 08:50:49 8556 3 Command: AUTH TLS
2012-06-28 08:50:49 8556 3 Trace: CFtpControlSocket::OnReceive()
2012-06-28 08:50:49 8556 3 Response: 234 Proceed with negotiation.
2012-06-28 08:50:49 8556 3 Status: Initializing TLS...
2012-06-28 08:50:49 8556 3 Trace: CTlsSocket::Handshake()
2012-06-28 08:50:49 8556 3 Trace: CTlsSocket::ContinueHandshake()
2012-06-28 08:50:49 8556 3 Trace: CTlsSocket::OnSend()
2012-06-28 08:50:49 8556 3 Trace: CTlsSocket::OnRead()
2012-06-28 08:50:49 8556 3 Trace: CTlsSocket::ContinueHandshake()
2012-06-28 08:50:49 8556 3 Trace: CTlsSocket::OnRead()
2012-06-28 08:50:49 8556 3 Trace: CTlsSocket::ContinueHandshake()
2012-06-28 08:50:49 8556 3 Trace: CTlsSocket::Failure(-12, 10053)
2012-06-28 08:50:49 8556 3 Trace: GnuTLS alert 40: Handshake failed
2012-06-28 08:50:49 8556 3 Error: GnuTLS error -12: A TLS fatal alert has been received.
2012-06-28 08:50:49 8556 3 Trace: CRealControlSocket::OnClose(10053)
2012-06-28 08:50:49 8556 3 Trace: CControlSocket::DoClose(64)
2012-06-28 08:50:49 8556 3 Trace: CFtpControlSocket::ResetOperation(66)
2012-06-28 08:50:49 8556 3 Trace: CControlSocket::ResetOperation(66)
2012-06-28 08:50:49 8556 3 Error: Could not connect to server
2012-06-28 08:50:49 8556 3 Trace: CFileZillaEnginePrivate::ResetOperation(66)