Table of Contents
CAS is an open-source Single Sign On (SSO) provider that allows multiple applications and services to authenticate against it and brokers those authentication requests to a back-end authentication provider. This module allows Guacamole to redirect to CAS for authentication and user services. This module must be layered on top of other authentication extensions that provide connection information, as it only provides user authentication.
The CAS authentication extension is available separately from the main
guacamole.war. The link for this and all other
officially-supported and compatible extensions for a particular version of Guacamole are
provided on the release notes for that version. You can find the release notes for
current versions of Guacamole here: http://guacamole.apache.org/releases/.
The CAS authentication extension is packaged as a .tar.gz
file containing only the extension itself,
guacamole-auth-cas-1.1.0.jar, which must
ultimately be placed in GUACAMOLE_HOME/extensions.
Guacamole extensions are self-contained .jar files which are
located within the GUACAMOLE_HOME/extensions directory.
If you are unsure where GUACAMOLE_HOME is located on
your system, please consult Chapter 5, Configuring Guacamole before
proceeding.
To install the CAS authentication extension, you must:
Create the
GUACAMOLE_HOME/extensionsdirectory, if it does not already exist.Copy
guacamole-auth-cas-1.1.0.jarwithinGUACAMOLE_HOME/extensions.Configure Guacamole to use CAS authentication, as described below.
The CAS authentication extension provides two configuration properties, both of which are required.
- cas-authorization-endpoint
The URL of the CAS authentication server. This should be the full path to the base of the CAS installation.
- cas-redirect-uri
The URI to redirect back to upon successful authentication. Normally this will be the full URL of your Guacamole installation.
- cas-clearpass-key
If using CAS ClearPass to pass the SSO password to Guacamole, this parameter specifies the private key file to use to decrypt the password. See the section on ClearPass below.
Guacamole will only reread guacamole.properties and load
newly-installed extensions during startup, so your servlet container will need to be
restarted before CAS authentication can be used. Doing this will
disconnect all active users, so be sure that it is safe to do so prior to
attempting installation. When ready, restart your servlet container
and give the new authentication a try.
CAS has a function called ClearPass that can be used to cache the password used for SSO authentication and make that available to services at a later time. Configuring the CAS server for ClearPass is beyond the scope of this article - more information can be found on the Apereo CAS wiki at the following URL: https://apereo.github.io/cas.
Once you have CAS configured for credential caching, you need to configure the service with a keypair for passing the credential securely. The public key gets installed on the CAS server, while the private key gets configured with the cas-clearpass-key property. The private key file needs to be in RSA PKCS8 format.