First of all do you need to have SSH access on both machines that you want to set up authentication with. I will describe how to do this mostly manually with command prompt / terminal.

Local machine

Log in with SSH to the machine you want to be authenticated. From here you can easily generate a RSA key pair by running the command:

ssh-keygen

This will create a .ssh/ directory with a id_rsa and a id_rsa.pub file inside.
The id_rsa file is your private key, which you should always keep secret. The other id_rsa.pub file is your public key which we will use to authenticate your machine.

To output the key to the console, run the cat command:

cat ~/.ssh/id_rsa.pub

The output will look something like this:

Copy this to your clipboard, we will use this to authenticate your machine.

Remote Machine

Now log in to your remote machine with SSH. Here you will also need to make a .ssh/ directory with the file authorized_keys inside it.

You can run the command nano to make and edit the file:

nano ~/.ssh/authorized_keys

Then you just paste the contents of id_rsa.pub and save.

Some hosting providers will also have an easy method of adding SSH keys:

Now have you successfully authenticated your local machine for your remote machine!

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