I was able to get the authentication working with active directory.
Here were the references that I used:
http://msdn.microsoft.com/en-us/library/ms998360.aspx
http://blog.jumptree.com/2008/active-directory-and-aspnet-forms-authentication
In the web.config file, the following modifications were made:
1. In the connectionStrings element, I added:
<add name ="ADConnectionString"
connectionString="LDAP://mydomain.com/DC=mydomain,DC=com"/>
where mydomain would be your own domain name.
2. In the system.web element, the following were added:
<authentication mode="Forms">
<forms name=".ADAuthCookie"
timeout="10"/>
</authentication>
<membership defaultProvider="MyADMembershipProvider">
<providers>
<add name="MyADMembershipProvider"
type="System.Web.Security.ActiveDirectoryMembershipProvider,
System.Web, Version=2.0.0.0,
Culture=neutral,
PublicKeyToken=b03f5f7f11d50a3a"
connectionStringName="ADConnectionString"
connectionUsername="yourusername"
connectionPassword="yourpassword"
attributeMapUsername="sAMAccountName"/>
</providers>
</membership>
where yourusername is a valid user that can access the active directory and yourpassword is the corresponding password for that user.
The key item for me to get it working correctly was that my user's don't have to enter a domain name. In order for the authentication to work, I had to add the:
attributeMapUsername="sAMAccountName"
to the providers element.