How to allow different IP address for control and data FTPS?

Question

Hi
I'm using FTPS (it's a client requirement and can't be changed) and it's hosted on Azure. And using your component in a net core app. I'm using PASV mode.

When trying to retrieve a file the following exception is thrown:

Rejected data connection for transfer of "MyFile", IP addresses of control and data connection do not match (425).

In other clients, it's possible to disable this check. Is that something that I can do with yours?

Thanks

Answer 1

This is actually a server-side error - the check has been performed by the FTP server, not the FTP client. It indicates that the from the server's point of view, the data connection was established from a different IP address than the control connection, which seems strange, and most likely has something to do with the client-side network configuration. Please create a log using Ftp object's LogWriter property (as described at https://www.rebex.net/kb/logging/) and either post it here or mail it to us at support@rebex.net for analysis. This should make it possible to tell what is actually going on from the client's point of view.

Comments

Thanks. The server has multiple outbound addresses so I would imagine that this was getting in the way. The server has been changed to allow addresses from a /24, so that's fixed it for me. Thanks for your help!

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Thanks a lot! It looks like this might actually be caused by an omission on our part - we don't currently bind the local endpoint of the data connection's socket to the IP address used by the control connection. Doing so would resolve the problem even when using multiple outbound addresses. We will look into that and fix it for the next release.