Created tirsdag 22 november 2016
SSH Keys are used instead of passwords - a fast authentication.
A quick info
SSH keys are generated in pairs - one public and one private. Share the public key all you want, but safeguard the private key.
The public key is then used to encrypt a message - the public key is NOT able to decrypt this very same message - so the trick is, that the public key gives you an encrypted message which only the private key-holder will be able to give the appropriate responds to.
Storage
# The keys is by default stored in ~/.ssh/
# The public key will be the one with the .pub suffix
Generate a pair of SSH keys
# We append -C to add a comment. In this case the user, host and date is used for easy verification
$ ssh-keygen -C "$(whoami)@$(hostname)-$(date -I)"
Permissions
# Change the permission of the folder/key
$ chmod 700 ~/.ssh
$ chmod 600 ~/.ssh/id_rsa
$ chmod 600 ~/.ssh/id_rsa.pub
# You will be prompted where to store the private key - leave this option to default (~/.ssh/)
# Choose a strong Password
Change Password on a private key - without changing the key itself
$ ssh-keygen -f ~/.ssh/key-id -p
Copy public key to remote server
# If the SSH server does not run on port 22, append the -p <PORT_NUMBER>
$ ssh-copy-id -i ~/.ssh/key_id.pub username@remote-server.org