Title: HowTo: Public Key Authentication
Description: Setting up a public key (non-password) login using ssh.

First, before starting, the following assumptions are made:

• You have enabled sshd on the remote server.
• You have opened the appropriate port for sshd on the remote server.
• You have configured tcp wrappers and/or other security mechanisms on the remote server.
• You are careful enough to know that you should not set up public key authentication for the root user.
• You are capable of choosing between RSA or DSA keys. (In this example I have chosen RSA.)

• Note: This is written for SuSE 9.2; other versions should be similar or identical.

1. If it does not exist, create the ~/.ssh directory for your user.

2. Generate the public / private key pair with the command

• Note: When prompted for a passphrase, just hit enter, and then enter again. See the man pages for ssh-keygen for various options, if you'd like to try something different. This will generate a private and a public (.pub) key file.

3. As root, edit the /etc/ssh/ssh_config file in the following ways:

• Remove the comment (#) from the line

  IdentityFile ~/.ssh/id_rsa

• Remove the comment (#) from the line

  Protocol 2

  (and while you are at it, if there is a 1 there, remove it; there should only be a 2 unless you have some strange reason to use protocol 1)

1. Log in to the remote server using the normal ssh password authentication.

2. Make sure the ~/.ssh directory exists.

3. Make sure permissions on the ~/.ssh directory are 700.

4. Now from the client machine copy the .pub key you generated to ~/.ssh on the server. You can do this with something like (from the client machine):

That will prompt you for a password to complete.

5. Now ssh to the server again, and run the following command:

6. Next, as root, edit the /etc/ssh/sshd_config file in the following ways:

• If the line

  Protocol 2 

  has a 1 as well, remove it unless you have some strange reason to use protocol 1. Also remove comment (#) if it is there.
• Edit the line

  PubkeyAuthentication yes

  (i.e. if it says no, change it to yes) Also remove comment (#) if it is there.
• Make sure the line

  AuthorizedKeysFile      .ssh/authorized_keys

  is set up correctly (i.e. if it is pointing to a different keys file, then update to what is shown here). Also remove comment (#) if it is there.

7. As root, restart sshd:

That's it. Now try logging in from your client machine - you should be logged in automatically without being prompted for a password.

Comments and Suggestions:
http://forums.suselinuxsupport.de/index.php?showtopic=18094∞

To add your own howto: http://forums.suselinuxsupport.de/index.php?showforum=50∞