SSH with key authentication failing

I’ve setup ssh access to my server with key authenitcation, and tested it from the terminal, and it works.
I then tried to setup a Duplicati backup using ssh with key authentication.
The key was generated with

ssh-keygen -t rsa

(because RSA is the only format supported by Duplicati, if I understood correctly)
What I put in the required fields is:

  • Username: the ssh user;
  • Password: the passphrase for the ssh key;

then I added the advanced option “ssh-keyfile”, and filled its field with the path to the key file.
The file is found correctly, however I keep getting the error
"Failed to connect: Failed to parse the keyfile, check the key format and passphrase. Error message was Key ‘OPENSSH’ is not supported."

Searching on the forum I wasn’t able to find anything useful (apart from the fact that the key must be an RSA one).

A thing that makes me wonder are the words in the description of the advaced option:
"[…] This option only works when using the managed SSH client."
What does that mean? Am I using the managed SSH client? I’m using the .deb package downloaded from the duplicati website, installed in a Debian Stretch chroot on a Debian Testing host.

Please ask me any other useful information that you need and I’ll give them you as soon as possible.


1 Like

It sounds like your key is using the new OPENSSH format, which Duplicati doesn’t support yet. Can you try the suggestion here to create a key with the old format?

ssh-keygen -m PEM -t rsa -b 4096

Thank you very much for your ultra-fast answer, it worked like a charm! This was my first question on this forum and I have to say that the support for Duplicati is outstanding!

Thanks for your help :slight_smile: