Question

SSH Key to Existing Droplet

Posted August 14, 2018 4k views
Security

I manually edited my authorized_keys file and added my ssh public key.
However when trying to login using the private key in putty I get a disconnected no supported authentication methods available (server sent publickey) error.
I read several threads here but can´t find any way to fix this.
Any ideas?

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2 answers

Hello friend!

The first thing I would do is make sure that your key pair is OpenSSH compatible. For example, this is one of my public keys and yours most likely looks the same:

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDLmqjzH1lJ+uTlL2yGjyOcFKdxYFWYLSUdqN5LMRA1YiXHJvTkOo4Ky8w8NmNqJoKwLhxESLNpdUteZbacCRf3I9j57td8IaySk3LFpNK1waDwPcwFlvOv6NtKdwFsgQ0CUqJ6Ya9AUVfTlyePBhH9lKy7gnsloAtHOfGlHdCt5X5f2iB0WU/PPZZskfj79z84dlUPrdfdq8DZmOQDnTEF6XnqaYIqrYXKnPOTovCnOGrc1xJjV+UQ7dZhc/5UCECDK8DEUKZ21aK5htCwhqQFLVV4M6SB7/mDiWXvNx79hKuHDHsHCv6L4YuqHkHAGNtmHq2UxntJ9K6i0DxoMq/1 jarlanddonnell@Jarlands-iMac.local

If all is well there, I would add the verbose flag to your SSH connection (ssh -vvv) and go over each line to see what it is doing. If it loads your private keys without error and moves forward without accepting login, I would suggest one of these is true:

  1. The server has been configured to not allow the login at all.
  2. The server is not loading an authorized_keys file that contains your public key.

I couldn’t say for sure which configuration had been changed to cause #1, but #2 should be fine if the public key is on a single line in authorized_keys under /root/.ssh or /home/username/.ssh (if not using root). More than likely I’ve already covered the problem area, taking a closer look at each detail should reveal something that you have not yet noticed. SSH login issues tend to not be very complex at their core.

Kind Regards,
Jarland

Hello there,

You can check our article on How to Upload an SSH Public Key to an Existing Droplet

https://www.digitalocean.com/docs/droplets/how-to/add-ssh-keys/to-existing-droplet/

You can access the droplet from the DigitalOcean console and then temporary enable the PasswordAuthentication on your droplet and access the droplet with a password to upload the ssh-key.

If you haven’t created new pair of keys you’ll need to do that first.

You can enable PasswordAuthentication for your Droplet by modifying your /etc/ssh/sshd_config file. Once set to Yes restart the SSH service and connect via an SSH client for a more stable connection. You can then modify your ~/.ssh/authorized_keys file to add the appropriate public key.

This change can be made from the DigitalOcean’s console. If you’re having issues accessing the console you can then reach to our amazing support team that can help you further with this.

To enable the PasswordAuthentication follow these steps:

  1. Login to the console on the DigitalOcean website.
  2. Type sudo nano /etc/ssh/sshd_config
  3. Change PasswordAuthentication from “no” to “yes” and save the file
  4. Open a terminal on your computer and type ssh username@[hostname or IP address] or if on a Windows box use PuTTY for password login making sure authentication parameters aren’t pointing to a private key
  5. Login with a password
  6. Type sudo nano ~/.ssh/authorized_keys
  7. Paste public key text here and save the file
  8. Type sudo nano /etc/ssh/sshd_config
  9. Change PasswordAuthentication from “yes” to “no” and save the file
  10. Log out and attempt to log back in (if using PuTTY make sure you set up auth parameters to point to your private key)

You can then upload the key using this command:

ssh-copy-id -i ~/.ssh/mykey user@droplet

Hope that this helps!
Regards,
Alex