Sharepoint AD user athenticate to another domain

I have a situation where I have to autheticate SharePoint user to another webs开发者_C百科ite that is not part of the sharepoint domain without asking user to login again.

I have sharepoint part of domain1. I have users in domain1 that log into sharepoint using NTLM by authenticating to domain1. I don't have any control over this domain and sharepoint configuration. I am working on a ASP.net application which needs to authenticate users from domain1 without prompting users for login if they have already logged into sharepoint server.

Is it possible to do? If yes please let me know how I can do this. I may be able to install a webpart on the Sharepoint if this allows me to do single sign on between sharepoint and my application.

---

If your web side (asp pages) are in domain 2, you can do it as follows:

1. Configure domain 2 to trust domain 1.
2. Create a group with all users in domain 1 that you want to give access to your asp pages
3. Configure your site to use windows authentication
4. Grant the user group access to your site

In this case it will not actually matter if they have logged into SharePoint first or not.