If you are using Basic Authentication or Forms-Based Authentication (FBA) with Microsoft Office SharePoint Server (MOSS) 2007 -- or any Web site, for that matter -- then you must configure secure communication (HTTPS) using SSL certificates.

However, you probably didn't select to enable SSL when you originally created your Web application (after all, you most likely don't want to use Basic Auth or FBA exclusively, but rather only for users accessing the site externally). If you followed the process I recommend for customers deploying MOSS solutions, you created the Web application using an intranet URL (e.g. http://fabrikam) and subsequently extended the Web application to the Internet zone (e.g. http://www.fabrikam.com) or Extranet zone (e.g. http://extranet.fabrikam.com) -- utilizing the SharePoint alternate access mappings feature.

Now that you need to enable secure communication, you might once again consider extending the Web application -- say to the Custom zone -- and select the option to use SSL (e.g. https://www.fabrikam.com). After all, this is the recommendation in the following TechNet article:

Update a Web application URL and IIS bindings (Windows SharePoint Services). (Updated 2009-04-23).

Specifically, here is the text that I am referring to:

We do not recommend reusing the same IIS Web site for your HTTP and SSL hosting. Instead, extend a dedicated HTTP and a dedicated SSL Web site, each assigned to its own alternate access mapping zone and URLs.

Wait a minute...let me see if I've got this right...you want me to extend my Web application -- thereby creating yet another copy of my Web.config files -- just to enable SSL? That doesn't seem like a good idea.

After all, managing the multitude of Web.config files across multiple Web application and Web servers in a farm seems to be one of the most challenging aspects for the Release Management and Operations teams (at least in my experience during the past several years). [I can't tell you how many times I've compared Web.config files during the process of troubleshooting various issues and found discrepancies due to manual changes not getting applied consistently. Sure, the risk of this is drastically reduced if you leverage the SPWebConfigModification infrastructure, but there are still rare occasions when a little manual "tweaking" is necessary -- and these often lead to inconsistent Web.config files.]

Therefore, one of my goals with any SharePoint solution is to minimize the number of Web.config files that are used. It seems reasonable to expect two different Web.config files to be used for a site that uses Windows Authentication internally and Forms Authentication externally, since this is configured using the <authentication> element.

For example, in the Default zone you probably want to specify:

    <authentication mode="Windows" />

Whereas in the Internet zone you instead need something like this:

    <authentication mode="Forms">
      <forms loginUrl="/Public/Pages/default.aspx" defaultUrl="/" />
    </authentication>

Okay, so if we want to avoid creating a new Web application -- and the corresponding Web.config file(s) -- how can we support both HTTP and HTTPS on the same Web application? It turns out to be rather simple.

For a starting point, let's assume you've just created your Web application using the default (i.e. intranet) URL -- say, http://fabrikam -- which uses Windows Authentication. This is the site that your content authors will use to manage the site.

The first step is to create an alternate access mapping (AAM).

To configure an alternate access mapping:

  1. On the SharePoint Central Administration home page, click the Application Management tab on the top link bar.
  2.  On the Application Management page, in the SharePoint Web Application Management section, click Create or extend Web application.
  3. On the Create or Extend Web Application page, in the Adding a SharePoint Web Application section, click Extend an existing Web application.
  4.  On the Extend Web Application to Another IIS Web Site page:
    1. In the Web Application section, select the Web application to extend (e.g. http://fabrikam).
    2. In the IIS Web Site section, in the Port and Host Header boxes, enter the corresponding values such as 80 and www.fabrikam.com, respectively.
    3. In the Security Configuration section, keep the default options (you can configure forms authentication, anonymous access, and SSL later).
    4. In the Load Balanced URL section, ensure the default value specified in the URL box is correct (e.g. http://www.fabrikam.com:80) and in Zone dropdown list, select Internet.
    5. Click OK.

The next step is to install your SSL certificate on the site. Once you've procured your certificate and installed it through Internet Information Services (IIS) Manager, you then need to add a public URL in SharePoint for HTTPS and add an HTTPS binding in IIS.

To add a public URL to HTTPS:

  1.  On the SharePoint Central Administration home page, click the Operations tab on the top link bar.
  2.  On the Operations page, in the Global Configuration section, click Alternate access mappings.
  3.  On the Alternate Access Mappings page, click Edit Public URLs.
  4.  On the Edit Public Zone URLs page:
    1. In the Alternate Access Mapping Collection section, select the Web application (e.g. http://fabrikam).
    2. In the Public URLs section, copy the URL from the Internet box to the Custom box, and change http:// to https://.
    3. Click Save.

To add an HTTPS binding to the site in IIS:

  1. Click Start, point to Administrative Tools, and then click Internet Information Services (IIS) Manager.
  2. In Internet Information Services (IIS) Manager, click the plus sign (+) next to the server name that contains the Web application, and then click the plus sign next to Sites to view the Web applications that have been created.
  3. Click the name of the Web application corresponding to the Internet zone (e.g. SharePoint – www.fabrikam.com80). In the Actions section, under the Edit Site heading, click Bindings….
  4. In the Site Bindings window, click Add.
  5. In the Add Site Binding window:
    1. In the Type: dropdown, select https.
    2. In the SSL Certificate: dropdown, select the certificate corresponding to the site (e.g. www.fabrikam.com).
    3. Click OK.
    4. In the Site Bindings window, click Close.

At this point, your SharePoint site supports Windows Authentication both internally (via http://fabrikam) and externally (via http://www.fabrikam.com and https://www.fabrikam.com). The final steps are to enable anonymous access and configure Forms Authentication.

Note that after configuring Forms Authentication, users will not automatically be redirected from HTTP to HTTPS for the login page. To achieve this user experience, I've used a couple of techniques in the past that are based on the same fundmental concept. The first technique utilized code on the login page to automatically detect HTTP connections and redirect to HTTPS. The second technique was essentially the same logic, but rather than utilizing code embedded in the login page, it is encapsulated in a Login Form Web Part. I'll discuss this redirect code in a follow-up post.