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One of the ways Platform.sh keeps things secure is by using SSH behind the scenes. Users can interact with their environment through a command shell, or push changes to the environment’s Git repository, and both of these features rely on SSH.

Secure Shell Protocol, SSH, supports certificate-based and keypair-based authentication. Certificate-based authentication is faster to set up and generally easier to use, provided you have a web browser available on your computer. Alternatively, you may use keypair-based authentication if you are setting up an automation tool, or simply prefer that method.

Automation tools may also use an API Token.

Certificate-based authentication 

To connect using certificate-based authentication, install the Platform.sh CLI.

Once installed, you may run platform login or any CLI command that would require authentication. In either case, a browser window will open and ask you to login with your Platform.sh account credentials. This web page is already encrypted with TLS over HTTP, making it secure.

The login process will issue a certificate that gets stored in your local SSH configuration. The certificate is automatically cycled every hour for a new certificate as long as your session is active. If you are inactive for an extended period your certificate will expire, and the system will ask you to login again the next time you use a command that requires authentication.

Keypair-based authentication 

This process requires two RSA keys:

  • A private key kept secret by the user
  • A public key stored within the Platform.sh account

These keys are called the public-private keypair and usually look like random lines of characters, like this:

A private key:

-----BEGIN RSA PRIVATE KEY-----
MIIEowIBAAKCAQEAtpw0S4DwDVj2q04mhiIMkhvrYU7Z6hRiNbTFsqg3X7x/uYS/
dcNrSvT82j/jSeYQP3Dsod9GERW+dmOuLaFNeiqOStZi6jRSWo41hCOWOFbpBum3
ra1n6nUO1wa/7O5wbgzhUOfnim77oOK0UgkqPArBCNXiNFTUJAvRyVmCtvJOyrqz
...(20 more lines like this)...
cPjJ/wKBgGd3eZIBK6Ak92u65HYXgY9EcX3vBNP4NsF087uxV4YfrM18KlGf5I87
QGerp3VKaGe0St3ot57GlwCAQUJAf1mit8qDTi0I8MhBe7q2lstXkBvde7GY1gKx
Kng4ohG6xHZ/OvC9tq7/THwAvleaxgLZN5GyXfAqNylDdZ0LtSjl
-----END RSA PRIVATE KEY-----

A public key (one very long line):

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC2nDRLgPANWParTiaGIgySG+thTtnqFGI1tMWyqDdfvH+5hL91w2tK9PzaP+NJ5hA/cOyh30YRFb52Y64toU16Ko5K1mLqNFJajjWEI5Y4VukG6betrWfqdQ7XBr/s7nBuDOFQ5+eKbvug4rRSCSo8CsEI1eI0VNQkC9HJWYK28k7KurMdTN7X/Z/4vknM4/Rm2bnMk2idoORQgomeZS1p3GkG8dQs/c0j/b4H7azxnqdcCaR4ahbytX3d49BN0WwE84C+ItsnkCt1g5tVADPrab+Ywsm/FTnGY3cJKKdOAHt7Ls5lfpyyug2hNAFeiZF0MoCekjDZ2GH2xdFc7AX/ your_email_address@example.com

GitHub has a good walk-through of creating an SSH keypair on various operating systems.

A keypair is valid for as long as you have access to the private key on the system from which you are connecting. If you have a keypair available you will not be prompted to login.

Find your Public-Private keypair 

If you use Linux, you probably already have keys. The private key is usually in a file named ~/.ssh/id_rsa and the public key in ~/.ssh/id_rsa.pub.

Searching for a public key file:

  1. Open up a command prompt.

  2. Run the following commands:

    $ cd ~/.ssh
    $ ls -a
    id_rsa
    id_rsa.pub
    known_hosts
    authorized_keys
    

    If you find a file named id_rsa.pub, you can use it with Platform.sh. If you don’t find an existing key, see the steps to create a new one in the next section.

Create a New Public-Private Keypair 

Create a public-private keypair:

$ ssh-keygen -t rsa -C "your_email_address@example.com"

ssh-keygen generates the key pair and will ask you where you want to save the file:

Generating public/private rsa key pair.
Enter file in which to save the key (/Users/your_username/.ssh/id_rsa):

The default location is fine in most cases. Now it’s time to create a passphrase. A good, strong passphrase is highly recommended, to make your key less useful if it falls into the wrong hands.

Enter passphrase (empty for no passphrase): [Type a passphrase]
Enter same passphrase again: [Type passphrase again]

That’s it. Keys generated! Here are the results:

Your identification has been saved in /Users/your_username/.ssh/id_rsa.
Your public key has been saved in /Users/your_username/.ssh/id_rsa.pub.
The key fingerprint is:
55:c5:d7:a9:1f:dc:7a:67:31:70:fd:87:5a:a6:d0:69 your_email_address@example.com

Add the SSH key to your Platform account 

  1. First off, you’ll need to copy your public key to the clipboard.
  2. Head over to your user account page on the Platform.sh Accounts page and navigate to the Account Settings tab.
  3. In the left side-bar, select SSH keys.
  4. Click the Add a public key button.
  5. Paste the key that you copied earlier into the ‘Key’ text box. You can also add a title if you like, otherwise it will be auto-generated.
  6. Click ‘Save’.

That’s it! You’re all set. Now you’ll be able to use Git and command shells with any Platform.sh environment that your user account is authorized to work with.

Forwarding keys by default 

It may be helpful to set your SSH client to always forward keys to Platform.sh servers, which can simplify other SSH or Rsync commands. To do so, include a block in your local ~/.ssh/config file like so:

Host *.us.platform.sh
       ForwardAgent yes
Host *.eu.platform.sh
       ForwardAgent yes

Include one Host entry for each Platform.sh region you want to connect to, such as us-2 or eu-4. (You can include other configuration as desired.)

SSH to your Web Server 

In the management console header, click on the environment tab and select the environment that you want to SSH into. Then click the SSH dropdown button towards the top right.

$ ssh wk5fqz6qoo123-master@ssh.eu.platform.sh

   ___ _      _    __
  | _ \ |__ _| |_ / _|___ _ _ _ __
  |  _/ / _` |  _|  _/ _ \ '_| '  \
  |_| |_\__,_|\__|_| \___/_| |_|_|_|

 Welcome to Platform.

 This is environment master
 of project wk5fqz6qoo123.

web@wk5fqz6qoo123-master--php:~$

Troubleshoot SSH 

While trying to log in via SSH, this can happen:

$ ssh [SSH-URL]
Permission denied (publickey).

Don’t panic! It’s an issue which can happen for the following reasons:

  • Your environment is inactive
  • You haven’t redeployed (i.e. git push) your environment since adding the new public key
  • You didn’t upload your public key to your user profile
  • Your SSH private key has not been added into your ssh-agent
  • Your SSH key files have incorrect permissions

Check your public key 

Make sure your public key has been uploaded to your user account.

Check your ssh-agent 

Check that your key is properly added to your SSH agent. This is an authentication agent that manages your private key.

  1. Check your SSH agent. Run the command ssh-add -l in your terminal:

    $ ssh-add -l
    2048 12:b0:13:83:7f:56:18:9b:78:ca:54:90:a7:ff:12:69 /Users/nick/.ssh/id_rsa (RSA)
    
  2. Check that file name on the right (.ssh/id_rsa in the example above). Does it match your private key file?

  3. If you don’t see your private key file, add your private key:

    $ ssh-add path-to-your-key
    
  4. Try again.

Specify your identity file 

If your identity (SSH key) associated with Platform.sh is not in a default file name (as may be explained in your SSH software manual, for example) you may have to append a specification like the one below so that the SSH software finds the correct key.

Host platform.sh
IdentityFile ~/.ssh/id_platformsh

Be aware that, above, platform.sh stands for a hostname. Each different hostname you connect to Platform.sh at may have to be specified in the host line, separated by spaces.

Still having trouble? 

If you followed all the steps above, you may also notice an error message similar to below while attempting to SSH to platform.sh:

Hello Your Name, you successfully connected, but you do not have access to service 'xxxxxxxxxxxxxx-master': check permissions.
Received disconnect from 54.210.49.244: 14: No more auth methods available

This usually means a deployment has not been committed yet. When a new key is added, it only becomes immediately active for use with Git. For use with SSH, it will not be activated until a deployment is made. An easy way to force this is to create and push an empty commit:

$ git commit --allow-empty -m 'force redeploy'
$ git push origin master

Generate SSH debug information 

If your private key and public key both look OK but you don’t have any luck logging in, print debugging information. These lines often give clues about what is going wrong.

  1. Run the SSH command with the -v option, like this:

    $ ssh -v [SSH-URL]
    OpenSSH_6.7.8, OpenSSL 1.2.3 1 Sep 2014
    debug1: Connecting to ssh.eu.platform.sh [54.32.10.98] port 22.
    debug1: Connection established.
    debug1: identity file /Users/nick/.ssh/id_rsa type 1
    ...(30 more lines of this light reading)...
    debug1: Offering RSA public key: /Users/nick/.ssh/id_rsa
    debug1: Authentications that can continue: publickey
    debug1: No more authentication methods to try.
    Permission denied (publickey).
    

    or

    $ GIT_SSH_COMMAND="git -v" git clone [REPO-URL]
    

You can use this information to make one last check of the private key file.

If you’re still stuck, don’t hesitate to submit a support ticket, we’ll help you solve your problem.