Problems backing up FMC to new SFTP server

[ABaker94985]

We're trying to migrate backups on our FMC to a new SFTP server. Various other network devices are using the remote storage, but we're not able to get any of our FMCs to backup. We currently have a physical and a virtual running 7.0.1 and a virtual running 6.6.4. Depending on the SFTP server configuration, we' re getting the following error messages on the FMC:

- Error  Cannot create a test file under directory /mnt/remote-storage or /mnt/remote-storage/sf-storage

This error seems like bug CSCvk40714, but I didn't see 7.0.1 listed. Also, with the top error, a test file is placed in the appropriate directory, and there are no errors on the server side. Every once in a while, a test will succeed, but a second push of the test button with no changes fail.

- Error   Cannot mounts SSHFS remote device, please verify the remote director name/username/password and advance options.

We are 100% sure the directory, username, and password are correct. The error on the SFTP server says "SSH Protocol Error: invalid key exchange value".

Is there some way to change the parameters on the FMC? What can I add into the advanced field to possibly correct this? Any other ideas as to what I might try? Thanks

[Rob Ingram]

@ABaker94985 what is your SFTP server? In the past I've had issues uploading a backup to a linux server where the algorithms on the server (in my instance ubuntu) only supported the more secure algorithms, which the Cisco FMC/ISE did not support. So we had to modify the supported algorithms on the ubuntu server.

[ABaker94985]

Thanks for the input, Rob. It's a Windows 2019 server running Solarwinds Serv-U, and I can confirm that some of the less secure algorithms have been disabled on this server. Do you know which algorithms the FMC uses? I don't see a debug for SCP or SFTP, so it may fall under SSH. The server didn't specify what the FMC was using either.

[rawbert0-]

By any chance were you able to figure this out? Running the latest Serv-U with FMC 6.7.0 and experiencing the same issue.

[ABaker94985]

Negative, but we no longer have a problem. We've completely moved away from the Firepower platform.

[rawbert0-]

Thank you for the quick response on this. If I could office space these things, I would.