This removes the need to enter a password when you ssh into a remote host.
Create your private and public keys
This is only necessary if you don't already have a set of keys.
user.login$ ssh-keygen
Accepting all defaults creates a password-less RSA key in the current users home dir:
~/.ssh/id_rsa
~/.ssh/id_rsa.pub
If necessary, add or change the password use the '-p' switch.
Copy your Public Key to the Target Server
Add the contents of the client’s ~/.ssh/id_rsa.pub key to the target hosts ~/.ssh/authorized_keys.
user.login$ ssh-copy-id user.login@target.host.com
Alternatively, if you want to use a specific key:
user.login$ ssh-copy-id -i ~/.ssh/id_rsa.pub user.login@target.host.com
Note1: If the users home directory is a shared mount then the ~/.ssh folder will be the same on every server.
Note2: This should be the last time you have to enter you password for this connection.
Connecting to target server
Now that the users public key has been copied into the authorised_keys file, password-less connect using:
user.login$ ssh user.login@target.host.com