521 Not logged in – Secure authentication

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    After updating Cerberus from vrsion 5.0.2 to 5.0.4 i can’t connect to the FTP. From Cerberus LOG Board i have such a message:

    2012/07/16 13:38:47 [27] 521 Not logged in – Secure authentication required

    2012/07/16 13:38:47 [27] The client closed the connection

    2012/07/16 13:38:47 [27] Connection terminated

    Before update everthing worked fine. I’ve tried already changing configuration with Secure Control and Secure Data selected but nothing has changed. I have to say that I’m trying to connect from the same machine where serever is build. Any clue whet’s wrong?



    It is one of two issues. Either the FTP interface is set to allow only encrypted FTP connections or the user account is configured to only allow encrypted FTP connections. The require encryption setting can be enabled at either the interface or user level.

    Go to the Interfaces tab of the Server manager and select the FTP interface matching the IP address your users are logging in on. This is not the same as the Default interface. Check out the Interfaces help for more information on the difference.

    You can remove the requirement for secure connections by unchecking the “Require Secure Control” and “Require Secure Data” options for the interface.

    You should also check the user account in the User Manager. Click on the Constraints tab for the user and see if the above two options are set.

    However, the better answer is to just switch to an FTP client that supports FTPES connections and use encryption. Using plain, unencrypted FTP is not recommended.


    I thought I would update this post with more information. If you wish to allow unsecured FTP connections, follow the instructions in this FAQ entry:

    How can I configure the server to allow unencrypted FTP connections?

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