Single sign-on is supported for the following scenarios:
You are using Forms authentication and you need to share user identity across applications that run on the same domain and all of them use the standard ASP.NET 2.0 Forms authentication. You need to ensure that:
1. All applications use the same user database or at least the same user names. You may need to integrate the authentication using a custom security handler.
2. The web.config file of all applications uses the same authentication cookie name and the path is set to "/":
<forms name=".ASPXFORMSAUTH" path="/" ...="" />
3. The web.config file of all applications uses the same machine key. The machine key is not present in the web.config by default. You can generate is using various machine key generators that can be found on the Internet. Once you have a key generated, you can add it to the <system.web> section the following way:
<machineKey validationKey="ABCD0708...." decryptionKey="DDFF8943...." validation="SHA1" />
4. If your applications run on different sub-domains, such as www.example.com and forums.example.com, you need to set the domain attribute of the authentication cookie to the main domain so that it's shared across domains:
<forms name=".ASPXFORMSAUTH" path="/" domain=".mywebsite.com" ...="" />
You are using Windows authentication. In this case, the user identity is shared within the Windows domain. No additional configuration is required.