- First, install OpenSSH on two UNIX machines, hurly and burly. This works best using DSA keys and SSH2 by default as far as I can tell. All the other HOWTOs I’ve seen seem to deal with RSA keys and SSH1, and the instructions not surprisingly fail to work with SSH2.
- On each machine type ssh somemachine.example.com and make a connection with your regular password. This will create a .ssh dir in your home directory with the proper perms.
- On your primary machine where you want your secret keys to live (let’s say hurly), type
- ssh-keygen -t dsa
This will prompt you for a secret passphrase. If this is your primary identity key, make sure to use a good passphrase. If this works right you will get two files called id_dsa and id_dsa.pub in your .ssh dir. Note: it is possible to just press the enter key when prompted for a passphrase, which will make a key with no passphrase. This is a Bad Idea ™ for an identity key, so don’t do it! See below for uses of keys without passphrases.
- scp ~/.ssh/id_dsa.pub burly:.ssh/authorized_keys2
Copy the id_dsa.pub file to the other host’s .ssh dir with the name authorized_keys2.
- Now burly is ready to accept your ssh key. How to tell it which keys to use? The ssh-add command will do it. For a test, type
- ssh-agent sh -c 'ssh-add < /dev/null && bash'
This will start the ssh-agent, add your default identity(prompting you for your passphrase), and spawn a bash shell. From this new shell you should be able to:
- ssh burly