Skip navigation

Central Authentication Server (CAS)

Last Updated: April 3rd, 2019


Duo Security's two-factor authentication is able to secure access to Central Authentication Server (CAS) deployments, complete with self-service enrollment and Duo Prompt.

Duo Security does not provide a native CAS integration. Unicon includes support for Duo in their third-party multifactor module for CAS 4.1.x. See Unicon's CAS-MFA project wiki for additional information.

CAS 5.0.x includes Duo multifactor support. See the CAS Documentation for configuration instructions.

Connectivity Requirements

This application communicates with Duo's service on TCP port 443. Firewall configurations that restrict outbound access to Duo's service with rules using destination IP addresses or IP address ranges aren't recommended, since these may change over time to maintain our service's high availability. If your organization requires IP-based rules, please review this Duo KB article.

First Steps

  1. Sign up for a Duo account.
  2. Log in to the Duo Admin Panel and navigate to Applications.
  3. Click Protect an Application and locate CAS (Central Authentication Service) in the applications list. Click Protect this Application to get your integration key, secret key, and API hostname. (See Getting Started for help.)

Treat your secret key like a password

The security of your Duo application is tied to the security of your secret key (skey). Secure it as you would any sensitive credential. Don't share it with unauthorized individuals or email it to anyone under any circumstances!

Configure CAS

Download and apply the Unicon MFA plugin overlay for CAS 4.1.x to your CAS deployment or configure Duo within CAS 5.0.x, using the application information from step one above.


Need some help? Take a look at our CAS Knowledge Base articles or Community discussions. For further assistance, contact Support.