Generate and Add SSH Keys

To take full advantage of Pantheon, you should load your public SSH key into your account. SSH keys are a best practice for authentication, allowing you more security than a simple password. You will only need to do this once for each work environment (laptop, desktop, etc.), no matter how many sites you work on.

Generate SSH Key

1. Open your terminal and enter the following command to generate a key:

   ssh-keygen

   This command works on Linux, MacOS, and Windows 10.

2. Unless you have reason to change it, leave the default location of ~/.ssh/id_rsa. If the command says the key already exists, you can either overwrite it or continue onto the next step with your existing key.

3. A passphrase is recommended to provide greater security, but can conflict with tools that cannot handle them.

4. Once the files are created, copy the contents of ~/.ssh/id_rsa.pub to your clipboard.

   Linux and Mac users can catthe file to the terminal and copy the output:

   cat ~/.ssh/id_rsa.pub

   Windows users can achieve the same result with type:

   type .ssh\id_rsa.pub

Add Your SSH Key to Pantheon

Add SSH Key - New Dashboard

1. Log in to your Pantheon Dashboard, and go to the SSH Keys tab of your User Profile's Personal Settings page.

2. Click Add New Key.

3. Paste the copied public key into the box, and click Save.

   

   Your computer is now set up to securely connect to the Pantheon Git server. You can view a list of available keys on the same page.

Add SSH Key - Classic Dashboard

1. Log in to your Pantheon Dashboard and go to the Account tab in your User Dashboard.

2. Click SSH Keys.

3. Paste the copied public key into the box, and click Add Key.

   

   Your computer is now set up to securely connect to the Pantheon Git server. You can view a list of available keys on the same page.

Clone Your Site Code

1. In your Terminal environment, copy the SSH clone URL from the Connection Info of any site's Dev environment to clone your site code to your workstation.

2. If prompted, enter the passphrase you set above.

Remove SSH Key from Pantheon

Revoke SSH Key from Pantheon - New Dashboard

To revoke a key, go to the SSH Keys tab of your User Profile's Personal Settings page. Click the Revoke button next to the key you want to remove:

Remove SSH Key from Pantheon - Classic Dashboard

To delete a key, go to the Account tab of your User Dashboard and click SSH Keys. Click the Remove button next to the key you want to delete:

Site Access After Removing Keys

If you have active sites and no keys remaining, you can still access the sites. Make site changes via SFTP or Git using your account password to authenticate. If you sign in through Google and haven't defined a password, you can set one on the Reset Password page.

Troubleshooting

Authenticity & Fingerprint Prompts

Your first connection to any remote server over an SSH connection (like Git or SFTP) will prompt you to confirm the host identity:

The authenticity of host '[codeserver.dev.UUID.drush.in]:2222 ([IP.ADDRESS]:2222)' can't be established.
RSA key fingerprint is SHA256:yPEkh1Amd9WFBSP5syXD5rhUByTjaKBxQnlb5CahZZE.
Are you sure you want to continue connecting (yes/no)?

You can safely type yes and press enter to add the server's SSH key fingerprint to your computer's known_hosts file. Additional connections to this specific Pantheon container will complete successfully without prompts. However, you will be prompted to confirm connections following a container migration, which is part of regular maintenance on the platform. See the following Pro Tip to automatically accept all Pantheon connections.

Host *.drush.in
    StrictHostKeyChecking no
    # The settings on the next two lines are temporary until Pantheon updates the available key types.
    # If 'PubkeyAcceptedAlgorithms' causes an error, remove it.
    HostkeyAlgorithms +ssh-rsa
    PubkeyAcceptedAlgorithms +ssh-rsa

Connections Fail With: no matching host key type found. Their offer: ssh-rsa

OpenSSH 8.8 disables RSA signatures like the key type Pantheon uses.

While we are working to remedy this on the platform, OpenSSH 8.8 will return this error for CLI commands:

Unable to negotiate with 203.0.113.123 port 2222: no matching host key type found. Their offer: ssh-rsa

Solution: Until the key type is updated on the Pantheon platform, add ssh-rsa to the accepted algorithms in ~/.ssh/config:

Host *.drush.in
    # The settings on the next two lines are temporary until Pantheon updates the available key types.
    # If 'PubkeyAcceptedAlgorithms' causes an error, remove it.
    HostkeyAlgorithms +ssh-rsa
    PubkeyAcceptedAlgorithms +ssh-rsa

Control Path Error

You may receive the following error:

ControlPath too long fatal: Could not read from remote repository.

Check your SSH config files (by default, $HOME/.ssh/config and /etc/ssh/ssh_config) for a declaration like this:

Host *
ControlMaster auto
ControlPath ~/.ssh/control-%l.%r@%h:%p

There are two ways to fix this. First, try adjusting the Controlpath line as shown below:

Host *
ControlMaster auto
ControlPath ~/.ssh/control-%r

If this doesn't fix the issue, try creating an entry in your SSH configuration for your site specifically by its hostname. Don't use the ControlMaster option, instead use the ControlPath line as shown below, replacing SITE_UUID with your site's UUID:

Host *.SITE_UUID.drush.in
ControlPath ~/.ssh/control-%r

Server Refused to Allocate pty

This error occurs when a user is attempting to make a direct connection to Pantheon via SSH. Pantheon does not support direct SSH connections.

Authentication Prompts

Password requests may still occur after adding an SSH key to your Pantheon account if the corresponding key is not found by your local ssh-agent. Verify by listing the SSH fingerprints already loaded in your device's ssh-agent:

ssh-add -L | ssh-keygen -l -E md5 -f - | awk '{print substr($2,5)}'

The resulting string should match one of the keys listed in your User Dashboard.

To resolve, add your SSH key to the ssh-agent using the following command, replacing id_rsa with the name of your private key, if different:

ssh-add ~/.ssh/id_rsa

If you are using a Linux distribution such as Fedora 33 or later, make sure RSA keys are enabled in ~/.ssh/config:

Host *.drush.in
  PubkeyAcceptedKeyTypes=ssh-rsa