About SSH connections

Console

1. You use the SSH button in the Google Cloud console to connect to your VM.
2. Compute Engine sets a username and creates an ephemeral SSH key pair with the following configuration:
   • Your username is set as the username in your Google Account. For example, if the email address associated with your Google Account is [email protected], then your username is cloudysanfrancisco.
   • Your public and private SSH keys are stored in your browser session.
   • Your SSH key has an expiry of five minutes. Five minutes after Compute Engine creates the key, you can't use the SSH key to connect to the VM anymore.
3. Compute Engine uploads the public SSH key and username to metadata.
4. Compute Engine retrieves the SSH key and username from metadata, creates a user account with the username, and on Linux VMs, stores the public key in your user's ~/.ssh/authorized_keys file on the VM. On Windows VMs, Compute Engine doesn't store the public key on the VM.
5. Compute Engine grants your connection.

gcloud

1. You use the gcloud compute ssh command to connect to your VM.
2. Compute Engine sets a username and creates a persistent SSH key pair with the following configurations:
   • Your username is set as the username in your local machine.
     
   • Your public SSH key is stored in project metadata. If Compute Engine can't store the SSH key in project metadata, for example, because block-project-ssh-keys is set to TRUE, Compute Engine stores the SSH key in instance metadata.
   • Your private SSH key is stored on your local machine.
   • Your SSH key doesn't have an expiry. It is used for all future SSH connections you make, unless you configure a new key.
3. Compute Engine uploads the public SSH key and username to metadata.
4. Compute Engine retrieves the SSH key and username from metadata, creates a user account with the username, and on Linux VMs, stores the public key in your user's ~/.ssh/authorized_keys file on the VM. On Windows VMs, Compute Engine doesn't store the public key on the VM.
5. Compute Engine grants your connection.

Third party tools

1. You create an SSH key pair and username. See Create SSH keys for details.
2. You upload the public key and username to metadata. See Add SSH keys to VMs that use metadata-based SSH keys for details.
3. You connect to the VM.
4. Compute Engine retrieves the SSH key and username from metadata, creates a user account with the username, and on Linux VMs, stores the public key in your user's ~/.ssh/authorized_keys file on the VM. On Windows VMs, Compute Engine doesn't store the public key on the VM.
5. Compute Engine grants your connection.

Console

1. You use the SSH button in the Google Cloud console to connect to your VM.
2. Compute Engine sets a username and creates an ephemeral SSH key pair with the following configuration:
   • Your username is the username set by your organization's Cloud Identity or Google Workspace administrator. If your organization hasn't configured a username for you, or your project doesn't belong to an organization, Compute Engine uses your Google Account email, in the following format:

     USERNAME_DOMAIN_SUFFIX

     For example, if the email associated with your Google Account is [email protected], then your generated username is cloudysanfrancisco_gmail_com.
   • Your public SSH key is stored in your browser session and in your Google Account.
   • Your private SSH key is stored in your browser session.
   • Your SSH key has an expiry of three minutes. Three minutes after Compute Engine creates the key, you can't use the SSH key to connect to the VM anymore.
3. Compute Engine resolves your provided username to your OS Login account in the VM using NSS service modules.
4. Compute Engine performs IAM authorization using the AuthorizedKeysCommand, to ensure you have the required permissions to connect.
5. The AuthorizedKeysCommand retrieves the SSH key from your user account to provide it to OpenSSH in the VM.
6. Compute Engine grants your connection.

gcloud

1. You use the gcloud compute ssh command to connect to your VM.
2. Compute Engine sets a username and creates a persistent SSH key pair with the following configurations:
   • Your username is the username set by your organization's Cloud Identity or Google Workspace administrator. If your organization hasn't configured a username for you, Compute Engine uses your Google Account email, in the following format:

     USERNAME_DOMAIN_SUFFIX

     For example, if the email associated with your Google Account is [email protected], then your generated username is cloudysanfrancisco_gmail_com.
   • Your public SSH key is stored in your Google Account.
   • Your private SSH key is stored on your local machine in the google_compute_engine file.
   • Your SSH key doesn't have an expiry. It is used for all future SSH connections you make, unless you configure a new key.
3. Compute Engine resolves your provided username to your OS Login account in the VM using NSS service modules.
4. Compute Engine performs IAM authorization using the AuthorizedKeysCommand, to ensure you have the required permissions to connect.
5. The AuthorizedKeysCommand retrieves the SSH key from your user account to provide it to OpenSSH in the VM.
6. Compute Engine grants your connection.

Third party tools

1. You create an SSH key pair. See Create SSH keys for details.
2. You upload your public SSH key to your OS Login profile. See Add keys to VMs that use OS Login for details.

• Compute Engine stores your key in your Google Account.
• Compute Engine configures your username in the default format:
  

      USERNAME_DOMAIN_SUFFIX

  For example, if the email associated with your Google Account is [email protected], then your generated username is cloudysanfrancisco_gmail_com.