Server keeps asking for password after I've copied my SSH Public Key to authorized_keys

Question

I have an Ubuntu Server, running in a Cloud. I created a user (git). In the folder /home/git, I have created the .ssh/ dir, and the authorized_keys file.

But, when I put my SSH Public Key in the authorized_keys file, the server continues to ask me the password.

What I did wrong?

Answer 1

On the server side, the ssh daemon will log errors in /var/log/auth.log, so check that file to see what's being reported.

From the client side, when establishing the connection you can add the -v flag (or -vv or -vvv) to increase verbosity. You might be able to identify your problem this way.

Here are other things to check.

• Make sure /home/git/.ssh/authorized_keys is owned by git.
• Make sure /home/git/.ssh/authorized_keys has a mode of 600 (-rw-------).

Also check the /etc/ssh/sshd_config file.

• PubkeyAuthentication should be set to "yes"
• There is also the AuthorizedKeysFile directive which determines the path where the authorized keys should be located. Ensure it's commented out or on the default of %h/.ssh/authorized_keys.

Answer 2

You have to lock the user with passwd -l username , this will change /etc/shadow file by inserting a ! before the encrypted password. To unlock use passwd -u username.

Answer 3

There are different ways to solve this: you can configure either sshd (server-side) or ssh (client-side) not to use password authentication. Disabling password authentication on the server makes your server more secure, but you will be in trouble if you loose your key.

To make ssh (client-side) using pubkey authentication, add some options to the ssh command:

ssh -o PubkeyAuthentication=yes -o PasswordAuthentication=no -X git@server

If this works, you can set the PasswordAuthentication=no option permanently in the ssh client config file /etc/ssh/ssh_config system-wide or ~/.ssh/config user-specific (on details, see man ssh_config).