CAS ISAPI Installation

Owned by Brian Donnelly
Last updated: Aug 19, 2010Version comment
3 min read

Please follow these instructions to install and configure the CAS ISAPI Filter for IIS Web Sites and ASP applications.

Download and Install MsXML 6.0 (If Necessary)

  1. Download the appropriate version of MsXML 6.0 for your architecture from http://www.microsoft.com/Downloads/details.aspx?familyid=993C0BCF-3BCF-4009-BE21-27E85E1857B1&displaylang=en
  2. Run the installer

Download and Install the CAS ISAPI Filter

  1. Download the CAS ISAPI Installer from https://confluence.ucdavis.edu:8443/confluence/x/eFY
  2. Run the installer.
    The installer now starts with valid default values for all required settings that will result in your entire site being protected by the UC Davis production CAS server. If you wish to customize the settings this table will provide you with information on their function:

    Parameter

    Description

    Default

    CAS Server URL

    The base URL of the CAS server

    https://cas.ucdavis.edu/cas

    Session Timeout

    The time in minutes each local session should last before requiring a roundtrip to the CAS server to confirm authenticated status.

    4 hours (240 minutes)

    Cache Clean Timeout

    The time to wait between cleanings of the authentication cache. If you experience out of memory errors, decrease this.

    1 hour (60 minutes)

    URL(s)

    Strings to match against requested URLS. When matched, CAS authentication is enforced.

    / (Matches all URLs)

    CAS Login Path

    The path to the login URL on the CAS server

    login

    CAS Validation Path

    The path to the validation URL on the CAS server

    serviceValidate

    Service URL

    When set, users will be directed back to this URL during the initial authentication step.

    not set

    Authentication Header

    The request header that receives the authenticated user ID.

    CASUser

Deploy the CAS Filter to your Web Site

Windows Server 2008

Windows Server 2003 and earlier
  1. Start the Internet Information Services (IIS) Manager
  2. Click on your server and select "Stop" from the Actions.
  3. Click on your Web server instance in your Console. The default title of your Web server instance is "Default Web Site", unless you changed it.
  4. Select ISAPI Filters from the Features View.
  5. Select "Add..." from the Actions list and enter "CASAuthN" as the "Filter Name".
  6. Browse to the CASAuthN.dll.
    • Windows Server 2008 64-bit: It is installed with this path: "C:\WINDOWS\sysWOW64\inetsrv\CASAuthN.dll".
    • Windows Server 2008 32-bit: It is installed with this path: "C:\WINDOWS\system32\inetsrv\CASAuthN.dll".
  7. Click "Ok".
  8. Restart the IIS Web Service.
    1. Click on the Web server instance.
    2. Select "Restart" from the Manage Server Actions section.
  1. The Web Server and IIS Admin service must be stopped. Check the services dialog box and stop these services if they are running.
  2. Start the IIS Administrator Console
  3. Click on your Web server instance in your Console. The default title of your Web server instance is "Default Web Site", unless you changed it. It maybe hidden under "Console Root/Internet Information Server/NAME", where "NAME" is the name of your computer.
  4. Access the properties page via right click.
  5. Click on the "ISAPI Filters" tab.
  6. Click on "Add..." and enter "CASAuthN" as the "Filter Name".
  7. Browse to the CASAuthN.dll. It is installed with this path: "C:\WINDOWS\system32\inetsrv\CASAuthN.dll".
  8. Click "Ok" on all dialogs until you are back at the IIS Administrator.
  9. Restart the IIS Web Service.
    1. Right click on the local computer in the IIS Adminstrator.
    2. Select All Tasks->Restart IIS.

Done!

That's it! Test your new protection scheme by using a Web browser to try and access a URL on your Web server with one of the protected path settings you set in this installer. It should redirect you to your CAS authentication server. You can also verify that the dll was loaded correctly by following steps a-f above and checking the status of the recently entered filter. It should have a green arrow to the left pointing up. If not, the filter is failing on initializationt. Check the registry keys and all relevant files listed therein as well as the location of the dll. Please also consult the troubleshooting section for information on common errors.

Accessing the authenticated user id

The CAS ISAPI module sets the "CASUser" header by default, this can be overridden during the installation process. In any server-side processing script (ASP, ASP.NET, .NET, Cold Fusion) you will be able to access this variable to get the authenticated user id.

Do not use "remote_user" as the header value, Windows asserts complete control over this header and any settings by the ISAPI module will be discarded by Windows.

Editing the Configuration

The CAS client configuration can be edited after installation via a registry editor like regedit. To access the CAS ISAPI module settings, browse to: /HKEY_LOCAL_MACHINE/SOFTWARE/CASAuthN It is possible to set up more than four path matching expressions using this method. The ISAPI module can handle up to ten (10) path expressions.

Registry settings are loaded at module initialization. Therefore, you must restart IIS after editing the configuration via a registry editor in order for the module to register the changes.