SFTP Backups failing - Permission denied (publickey)

[ML_digital]

Hi,

We've got several 3CX systems backing up via SFTP to a FileZilla server we host and manage specifically for backing up 3CX instances. The systems are a combination of on-premise and self hosted in AWS but all do exhibit the same issue randomly. However, the backups randomly fail with the email error message:

Your 3CX backup failed due to the following reason(s):
Permission denied (publickey).

Looking through the logs, we get the below error message when the backups fail:

Your 3CX backup failed due to the following reason(s): Renci.SshNet.Common.SshAuthenticationException: Permission denied (publickey). at Renci.SshNet.ClientAuthentication.Authenticate(IConnectionInfoInternal connectionInfo, ISession session) at Renci.SshNet.ConnectionInfo.Authenticate(ISession session, IServiceFactory serviceFactory) at Renci.SshNet.Session.Connect() at Renci.SshNet.BaseClient.CreateAndConnectSession() at Renci.SshNet.BaseClient.Connect() at _3cxFilesystemImplementations.SFTP.SftpFileSystem.CreateSftpClient(LocationSettings settings) at _3cxFilesystemImplementations.SFTP.SftpFileSystem.Delete(String filename) at BackupRestoreSchedule.BackupJob.RotateFiles(IFilesystem filesystem, Int32 count, String filename) at BackupRestoreSchedule.BackupJob.Execute(IJobExecutionContext context)

Normally the backup fails once, then is fine for a few days before failing again.

We've checked and double checked all the configurations to make sure that there are no issues. We've even check against the guides for backing up 3CX and have even made sure the SSH keys are in the correct format as per https://www.3cx.com/docs/manual/convert-open-ssh-key/.

We've also made sure that 3CX backups happen at different times and that no updates happen during the backup window on each instance.

 

[TheodorosG_3CX]

This error is generated from the SFTP, so in this case you might need to check the SFTP logs as well.

 

[SweetAction]

via SFTP to a FileZilla server we host

Since when does Filezilla Server support SFTP? FTP(e/i)S, sure.

 

[ML_digital]

Sorry for the delay in responding. Been busy and this sort of fell on the back burner for now. I'm checking the SFTP configuration and making sure that it is correct. Also double checking the SFTP setup on FileZilla.

We've got FileZilla Pro Enterprise Server which supports SFTP.

 

[SweetAction]

We've got FileZilla Pro Enterprise Server which supports SFTP.

Ah, that explains it. Nevermind me then.