FTP Connector - "Failed to create 1-th FTP session..."

[JulesD]

Hello everyone, I am trying to open an FTP connection with the FTP connector node.
However the only result I get ist the following error code:

WARN  FTP Connector        0:4        Failed to create 1-th FTP session (0 sessions already opened). Please consider decreasing the maximum FTP sessions.
ERROR FTP Connector        0:4        Failed to initialize FTP client pool
WARN  FTP Connector        0:4        ConnectException: Connection refused: connect
ERROR FTP Connector        0:4        Execute failed: Connection refused: connect

I tried with two different ftp servers and I tried to decrease the maximum FTP sessions from the default value, but always the same result.

Can anyone help?

[temesgen-dadi]

Hi @JulesD,

Welcome to the KNIME Community forum!

This looks like a connection problem. It could be caused by missing proxy settings (within KNIME Analytics Platform) that are required to connect to those FTP servers. You can fined more detailed information about the errors shown in the console in the knime.log file, which can be accessed via View => Open KNIME log.

Can you please download and try the attached workflow which connects to a public ftp server (ftp.ebi.ac.uk)? You can import it to your knime workspace using File => Import KNIME Workflow
ftp_test.knwf (8.1 KB)

Regards,
Temesgen

[JulesD]

Hello Temesgen,
thanks a lot for your reply. I tried to access the public server which works fine so it seems to have something to do with the authentification.

I checked again my ftp settings. I am trying to log on a strato server that is using sftp and realized I used the wrong port. So if I use port 22 instead of port 21, I get at least a different error message, but the connection still fails.

WARN  FTP Connector        4:4        Failed to create 1-th FTP session (0 sessions already opened). Please consider decreasing the maximum FTP sessions.
ERROR FTP Connector        4:4        Failed to initialize FTP client pool
WARN  FTP Connector        4:4        MalformedServerReplyException: Could not parse response code.
Server Reply: SSH-2.0-OpenSSH_8.2
ERROR FTP Connector        4:4        Execute failed: Could not parse response code.
Server Reply: SSH-2.0-OpenSSH_8.2

Regards,
Julia

[thor]

There is a difference between FTP, FTPS, and SFTP. The FTP Connector node talks the FTP protocol. SFTP is a completely different protocol on top of SSH. FTPS on the other hand is the FTP protocol through an encrypted channel. It seems like your server is an SFTP server which means you cannot use the FTP Connector node for talking to it. What you need is the SSH Connector node.

[JulesD]

Hi thor,
thanks a lot for your explaination. I wasn’t aware of that.
The SSH Connector works just fine, I get a connection.

Thanks,
Jules