Mixing Forms authentication with Windows authentication

user_271727 0
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I have an (ASP.NET 3.5) intranet application which has been designed to use forms authentication (along with the default aspnet membership system). I also store additional information about users in another table which shares its primary key with the aspnet_users table.

For users who are part of our domain I store their domain account name in the secondary users table, and I want to automatically log in users whose domain account name matches a name stored in the table.

I have read the guides which are available - they're all from two years ago or more and assume that you are able to activate Windows Authentication on a separate login page that allows you to extract the domain account name. From what I can tell, though, this is not possible in IIS7 (the overall authentication method is applied on all pages and cannot be selectively deactivated, and both authentication methods can't be applied on the same page).

Is there a way of getting IIS to pass through the windows domain account name of the requesting user? I don't need proper AD authentication, just the domain name.

windows-authentication iis-7 forms-authentication asp.net
7 Answers

You could always set up 2 separate application in IIS7. One would have Windows Authentication enabled. The other would be the main app with forms authentication. If a user went to the windows authentication app, the page could grab their credentials and pass it to the forms authentication app.

David_342080

(More for completeness of information really)

I asked a .Net security guy this question at a conference a while back. His response was that it is technically possible, but he'd never seen it done (and to let him know if I did it and it worked!).

He suggested the way it could be done was by making your own ISAPI filter and installing it into IIS. The ISAPI filter would intercept the requests and basically do the job that IIS does when using integrated authentication, but fall back to using forms if this was not present. This involved some complicated challenge/response logic in the filter. This was for IIS6 though, so it might be different in IIS7.

Whilst this might be technically possible, I wouldn't suggest this route as it feels like a bit of a hack, and rolling your own security is never really a good idea (unless you really know what you are doing).

user_1169230

I've got something you can try - not sure if it will work.

In the past we've used Request.ServerVariables["LOGON_USER"] but obviously for this to return a non-empty value you need to disable Anonymous access.

See this article: http://support.microsoft.com/default.aspx/kb/306359

It suggests keeping Anonymous access on the IIS side, and Forms authentication, but denying the anonymous user as follows:

<authorization>
   <deny users = "?" /> <!-- This denies access to the Anonymous user -->
   <allow users ="*" /> <!-- This allows access to all users -->
</authorization>
user_2297220

Unfortunately, what you are trying to do just isn't supported. In order for ASP.NET to know the Windows username, you must use Windows Authentication.

You could set up another site / virtual directory that just forwarded the username information to another page. But what happens when non-Windows authenticated users try to log in?

user_220330
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