When you wish to log in to a server without having to enter a password, all you need to do is log in with SSH. However I do not know why, but it took me hours to find a simple way to do this a few years ago.
First of all, you need to generate your SSH keys using the following:
From this point, I generally just hit enter and use the defaults. You can set a password, but that can get annoying.
Now you need to copy the SSH keys to the server you wish to log in to. I have found many ways to do this, but none have been as simple as the following:
You will then be asked for your password for the last time. Once this has complete, you will be able to login to the server using just: