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The procedure for enabling institutional Single Sign On (SSO) via a central authentication service (CAS) that is not Shibboleth involves building or installing a CAS Apache module. That module might be a home-grown CAS-type module provided by your institution, or it might be the standard mod_auth_cas module, available from the Apereo CAS project (see: ). In addition, you will need to modify the Apache configuration for your LON-CAPA server to (a) load the module, and (b) configure LON-CAPA to use it, by default, when unauthenticated users access /adm/roles.

If your server will be part of the cluster of collaborating institutions, it is possible that users from other LON-CAPA domains might visit your server to log-in to LON-CAPA. To support that possibility, it is recommended that the CAS log-in page includes a link to point back at /adm/login on your LON-CAPA server, and the link is identified as one to be followed by users from other domains. See:, for an example.

In order for Apache to use your CAS system you need to set the PerlVar lonOtherAuthen to yes, and provide the default domain for SSO users and the authentication type (i.e., the name of your CAS).


  1. All files will contain HTML mark-up, but the sso_logout_head item is a fragment inserted into the head block of the standard LON-CAPA logout page, and similarly, the sso_logout_body is a fragment inserted into the body of the page, whereas the sso_failed_login.html file should be a complete HTML document.

    If the name of the PerlVar ends _ < dom > then the HTML fragment is only displayed to SSO users from that particular domain. It is possible that a LON-CAPA user from another domain might have used SSO authentication on a server in his/her home domain, and then switched session to your server, (e.g., for co-author access to an Authoring Space in your domain). In that particular case, if you wanted to display custom HTML, you should add a PerlVar with a name ending in _ < otherdom > . If you include PerlVars for lonSSOUserLogoutHeadFile and/or lonSSOUserLogoutMessageFile they will be included for SSO users who use the Logout link on your LON-CAPA regardless of the user's domain.

  2. If you enable self-creation of SSO-authenticated users, then the sso_failed_login.html document need not be created.

  3. If you would like the log-in again link on the logout page to point to a specific URL just for SSO users, then you would set the PerlVar for lonSSOReloginServer. However, if you would like the log-in link for all users from your domain (both SSO and non-SSO authenticated) to point at a particular URL, then you would log-in to LON-CAPA, select a Domain Coordinator role, and use Main Menu - > Set domain configuration - > Display ("Default authentication/language/timezone/portal/types" checked) an set the URL in "Portal/Default URL".