AUTH TLS command breaking the login on some FTP servers

[Chris]

Status: Resolving address of ftp.augustabenelux.nl
Status: Connecting to 46.44.148.131:21...
Status: Connection established, waiting for welcome message...
Response: 220 Titan FTP Server 10.01.1740 Ready.
Command: AUTH TLS
Error: Could not connect to server

Status: Waiting to retry...
Status: Resolving address of ftp.augustabenelux.nl
Status: Connecting to 46.44.148.131:21...
Status: Connection established, waiting for welcome message...
Response: 220 Titan FTP Server 10.01.1740 Ready.
Command: AUTH TLS
Error: Could not connect to server

==> "AUTH TLS" command is killing the login process on some FTP server when using "Quick Connect" on FileZilla. TLS should not be enforced on simple ​ftp:// login, or you should add a checkbox to activate/deactivate TLS, just next to the "Quickconnect" button. I don't know if this is a bug report or a feature request~ it is certainly a problem for inexperienced users.

==> Login works fine when:
a) Using the FileZilla Site Manager and picking the "Only use plain FTP (insecure)" option
b) Adding a network location within Windows
c) Using Internet Explorer

[Chris]

Version of FileZilla Client: 3.10.3

[Tim Kosse]

Either the server is broken or some firewall interrupts the connection.

If the server (or firewall) does not support or understand a particular command, it must reply with a 5yz reply code. Examples:

500 Syntax error, command unrecognized.
502 Command not implemented.

Contact your server administrator or server hosting provider for assistance so that the server can be fixed.

[Chris]

@ codequid: If you had read the complete ticket, you would have seen that the connection is working fine by using the Site Manager > Only use plain FTP (insecure). See below when using those:

Status: Resolving address of ftp.augustabenelux.nl
Status: Connecting to 46.44.148.131:21...
Status: Connection established, waiting for welcome message...
Status: Server does not support non-ASCII characters.
Status: Connected
Status: Retrieving directory listing...
Status: Directory listing of "/" successful

==> You can see that with the same firewall/server the behavior is different/successful because the flipping software is NOT sending that "AUTH TLS" command.

[Tim Kosse]

If the server (or firewall) does not support or understand a particular command, it must reply with a 5yz reply code instead of dropping the connection.