V0.41 Cannot authenticate using OpenSSH key in SmarTTY

I just upgraded my MIAB box to 18.04 and 0.41. I have followed all the instructions for setting up RSA key authentication, but I can’t connect using SmarTTY or Cyberduck when I have password authentication set to no. I created the SSH key pair and while I had password authentication set to yes, I downloaded the id_rsa key file to C:\users\{myusername\.ssh. When I try to login with that key file in SmarTTY, I consistently get the message “Cannot authenticate using OpenSSH key. Login using password instead?” If password authentication is set to yes, I can, if no, I can’t.

I am using a DO droplet and I CAN log in with password from their console, but I would like to be able to use an offline SSH client. Why is this not working?

Did you configure the public key for this ssh key on the server? There is more configuration than just having the key on your computer.

A line that looks like this (in the steps in link below) needs to go in /home/{username}/.ssh/authorized_keys file:

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDNqqi1mHLnryb1FdbePrSZQdmXRZxGZbo0gTfglysq6KMNUNY2VhzmYN9JYW39yNtjhVxqfW6ewc+eHiL+IRRM1P5ecDAaL3V0ou6ecSurU+t9DR4114mzNJ5SqNxMgiJzbXdhR+j55GjfXdk0FyzxM3a5qpVcGZEXiAzGzhHytUV51+YGnuLGaZ37nebh3UlYC+KJev4MYIVww0tWmY+9GniRSQlgLLUQZ+FcBUjaqhwqVqsHe4F/woW1IHe7mfm63GXyBavVc+llrEzRbMO111MogZUcoWDI9w7UIm8ZOTnhJsk7jhJzG2GpSXZHmly/a/buFaaFnmfZ4MYPkgJD username@example.com

Information: https://www.digitalocean.com/community/tutorials/how-to-configure-ssh-key-based-authentication-on-a-linux-server

If running Windows, you may wish to try Termius and WinSCP instead.

Yes. The public key is in the authorized_keys file. I have double and triple checked. Maybe I need to open a DO ticket instead.

I have been using both SmartTTY and Cyberduck for a couple of years now. I WAS able to log into the previous version in both with no issues. I have other droplets on DO and I have NO issue with those so I’m not going to change software just for MIAB.

Out of curiosity, are you sending your login as root@x.x.x.x ? I’ve messed it up I can’t tell you how many times because I was using user@x.x.x.x, when DO used my key to set up a root user on the new droplet.

I finally got it to work. First I double checked the /etc/ssh/sshd_config file and commented out the line Use Pam yes. Then I deleted the existing files in /home/ubuntu/.ssh and ran ssh-keygen to get brand new keys. I then logged into SSH on SmarTTY using password and downloaded both id_rsa and id_rsa.pub files. Restarted SSH.

I am now able to log into SSH both in SmarTTY AND Cyberduck using id_rsa and passphrase. I also updated they public key on Digital Ocean in the event I want to use it again in the future.

I think maybe you were using an old key - which was probably regenerated during an upgrade or something. Either way, it’s working now!