Skip to content

Multi-factor Authentication

To improve security, access to Ruddle requires both a public key and multi-factor authentication (MFA). We use the same MFA (Duo) as is used elsewhere at Yale. To get set up with Duo, see these instructions.

You will need upload your ssh public key to our site. For more info on how to use ssh, please see SSH instructions.


Setting up a config file lets you re-uses your authenticated sessions.

Once you've set up Duo and your key is registered, you can finally log in. Use ssh to connect to your cluster of choice, and you will be prompted for a passcode or to select a notification option. We recommend choosing Duo Push (option 1). If you chose this option you should receive a notification on your phone. Once approved, you should be allowed to continue to log in.


You can set up more than one phone for Duo. For example, you can set up your smartphone plus your office landline. That way, if you forget or lose your phone, you can still authenticate. For instructions on how to add additional phones go here.

File Transfer Clients and Duo MFA

Some file transfer clients attempt new and sometimes multiple concurrent connections to transfer files for you. When this happens, you will be asked to Duo authenticate for each connection. Here are some application-specific tips on how to avoid having to authenticate for each new connection:


New Site
In host
(new site will be highlighted, change to your cluster name)
In the general tab on the right side, put:
Change protocol to SFTP
set user to your netid
set login type to "Key file"
browse to and select your putty key file
set login type to "Interactive"
Go to transfer settings tab
check limit number of simultaneous connections
Make sure maximum is 1
click ok

Now to connect,
select the site you created
click connect

Other Client Recommendations

  • Cyberduck (Windows/macOS)

Troubleshoot MFA

If you are having problems initially registering Duo, please contact the Yale ITS Helpdesk.

If you have successfully used MFA connect to a cluster before, but cannot now, first please check the following:

  • Test MFA using

  • Verify that your ssh client is using the correct login node

  • Verify you are attempting to connect from a Yale machine or via the proper VPN

If all of this is true, please contact us at Include the following information (and anything else you think is helpful):

  • Your netid
  • Have you ever successfully used ssh and Duo to connect to a cluster?
  • How long have you been having problems?
  • Where are you trying to connect from? (fully qualified hostname/IP, if possible)
  • Are you using a VPN?
  • What is the error message you see?