Ubuntu One Account

The standard way to manage and control Ubuntu Core devices is via SSH using public/private keys to authenticate. The user account on the device and the public SSH key are set up on first boot using an Ubuntu One account. You have to create an account and upload a public key using a browser on a different computer (not the Pi running Ubuntu Core). This documentation page contains detailed information about the account and SSH setup.

Start by going to login.ubuntu.com and selecting "I don’t have an Ubuntu One account" then fill in email, name, username, and password to create an account.

Create SSH Key

Creating an SSH key pair can be done easily on Linux or Mac. It's possible on Windows, but trickier. You can use another Raspberry Pi running Pi OS or Ubuntu Server OS to generate the SSH keys.

First create a directory to store keys in and restrict its permissions to be accessible only to the user that owns it with these commands.

mkdir -p ~/.ssh
chmod 700 ~/.ssh

mkdir -p ~/.ssh
chmod 700 ~/.ssh

Use the following commands to change directories and start the key generation wizard.

cd ~/.ssh/
ssh-keygen -t rsa

cd ~/.ssh/
ssh-keygen -t rsa

Respond to the following prompts in the keygen wizard

• File to save the key in. Enter "id_ubuntucore" or whatever name you want to give your keypair
• Passphrase is an extra password that must be entered in order to use the key. It can be left blank, but it's best to enter a passphrase and keep it secret. It acts as a second factor of authentication beyond just having the key file.
• Confirm Passphrase by entering the exact same value again.

The output of the wizard will look something like this once complete:

Generating public/private rsa key pair.
Enter file in which to save the key (/home/myuser/.ssh/id_rsa): id_ubuntucore
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in id_ubuntucore
Your public key has been saved in id_ubuntucore.pub
The key fingerprint is:
SHA256:NdKl6pErAxt4fVDNsptgbYwN5B66ZncxWeRk6Zs0Xro user@hostname
The key's randomart image is:
+---[RSA 3072]----+
|     .. .o+..    |
|     ....*+o     |
|      +*.+B      |
|   . ++o*B+..    |
|  . =.ooS= *     |
|   . = oo==      |
|    = + +  .     |
|   o . +  E      |
|                 |
+----[SHA256]-----+

Generating public/private rsa key pair.
Enter file in which to save the key (/home/myuser/.ssh/id_rsa): id_ubuntucore
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in id_ubuntucore
Your public key has been saved in id_ubuntucore.pub
The key fingerprint is:
SHA256:NdKl6pErAxt4fVDNsptgbYwN5B66ZncxWeRk6Zs0Xro user@hostname
The key's randomart image is:
+---[RSA 3072]----+
|     .. .o+..    |
|     ....*+o     |
|      +*.+B      |
|   . ++o*B+..    |
|  . =.ooS= *     |
|   . = oo==      |
|    = + +  .     |
|   o . +  E      |
|                 |
+----[SHA256]-----+

That will create two files, id_ubuntucore and id_ubuntucore.pub if you used the name quoted above.

As the file extension suggests id_ubuntucore.pub is the public key of this key pair. It needs to be copied onto the device you want to access with SSH. For Ubuntu Core, the copying happens by uploading the public key to your Ubuntu One account and entering your email in the first boot config.

The file with no extension, id_ubuntucore, is the private key file. Keep that file secure. Anyone who has that file and its passphrase can log in to control any computers configured with the public key.

Upload Public SSH Key to Ubuntu One

Go to: https://login.ubuntu.com/ssh-keys and use the import key section.

Open the id_ubuntucore.pub file in your text editor of choice or use cat in the terminal to print it. Copy the entire contents of the public key file and paste them into the import box on the ssh-keys page then click the Import SSH Key button.