This guide will explain how you can log in via SSH to a remote Raspberry Pi without using your password. As an added benefit, this process will also permit you to add the remote Pi in question to your ssh config file, and thus to log into it by simply typing, e.g. ssh raspberrypi from the command line.
Step 1
First, you will need to generate a set of SSH keys on your local computer — i.e. the one you’re using to SSH in to the remote Raspberry Pi. If you already have a set of SSH keys installed on your local computer, you can skip this step.
If you do not have keys installed on your local computer, you can generate a set by running the following (replacing [note] with your own note, of course):
ssh-keygen -t rsa -C "[note]"
There is no need to add a password to the key. This guide assumes that you will save the new keys in the suggested directory, which is ~/.ssh.
Step 2
Next, you will need to generate a set of SSH keys on the remote Raspberry Pi — i.e., the one you’re logging into — so that the necessary ~/.ssh folder structure is created, along with the known_hosts file. If you have already done this, you can skip this step. If you have not, repeat the instructions above on your remote Raspberry Pi.
Step 3
To copy your public SSH key over to the remote Raspberry Pi, we will use cat. You will need to know:
- The location in which your public SSH key is stored. If you installed the key using the exact process outlined in Step 1, this will be
~/.ssh/id_rsa.pub. If you saved the key elsewhere, make a note of its location on your local machine - The address of the remote Raspberry Pi to which you want to add the key
- Your username and password on the remote Raspberry Pi to which you want to add the key
Supposing that the public SSH key is located at ~/.ssh/id_rsa.pub, your username on the remote Raspberry Pi is charles, and your remote Raspberry Pi’s IP address is 10.0.1.2, you can copy the key over by running:
cat ~/.ssh/id_rsa.pub | ssh charles@10.0.1.2 'cat >> ~/.ssh/authorized_keys'
NOTE You will be prompted for your account password once you press enter.
Step 4
You will now be able to log in without using your password. To do this, you can type ssh followed by your username and the address of the remote Raspberry Pi. In our example, this would be:
ssh charles@10.0.1.2
Step 5
We strongly recommend saving your configuration in your SSH config file so that you can use easy-to-remember shortcuts to log in to all your devices. A full guide explaining how to do that can be found here.