Re: Windows Authentication, Single sign on and Active Directory


this does make sense, I'll try and proceed in this direction and see where
and how it goes. One thing I am not sure about is where and how active
directory is getting involved in here? Does it all happen behind the scene /
under the hood for me? What will happen if there is something else in place
of AD?

I think by now it must be obvious to you that I am a complete novice to this
whole thing.


"Joe Kaplan" <joseph.e.kaplan@xxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
The best thing to do would be to catch the appropriate exception if the
web service proxy client fails to connect due to authentication failure
and then prompt the user for credentials. You can then create a
NetworkCredentials object that contains the plain text credentials and use
that instead of the DefaultCredentials. This gives you SSO for users
logged in to the desktop but gives you a mechanism to handle situations
where it doesn't work. This is actually how the browser tends to work as

I can't remember the exact exception, but I'm sure you can figure it out
quickly through a little testing.

If you were working in an internet scenario instead of intranet, you might
also want to consider the possibility of using Basic authentication with
SSL. That will require you to always prompt for credentials, but is the
most flexible. Note that you should almost certainly be using SSL with
the web services anyway, as it is generally important to protect any
authenticated web traffic at the transport level, no matter what
authentication protocol you are using.

Joe K.

Joe Kaplan-MS MVP Directory Services Programming
Co-author of "The .NET Developer's Guide to Directory Services
"SP" <spspsp@xxxxxxxxxxxx> wrote in message
Thanks for the input Joe,

I do not want to implement my own protocol and anything readymade is
definitely the best option for me. I just got carried away reading lots
of different articles on internet but could not get anywhere in practice.
I think I was looking to replace the existing mechanism on a like for
like substitute.

One of the problems is, I need to keep the login dialog as well, in case
if a user logs in to the client machine outside the domain, then he
should be able to key in his credentials. The server is always in the
domain. for example, I am a domain usee as MyDomain\SP. On a client
machine, if I am logged in as one, then I want the application to not
show me a login dialog. If I am not logged on to the domain, I would like
for the application to show me a login dialog where I may enter
MyDomain\SP as user and my password to start using the application

As I had previously said, I don't know how to do it so can you please
point me to some examples if possible?



"Joe Kaplan" <joseph.e.kaplan@xxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
The more straightforward way to do this is to enable integrated Windows
authentication on the web services. If the user is logged into the
domain when running the client app, all you need to do is set the
Credentials property on your web service proxy classes to use
DefaultCredentials and the user will log in automatically (assuming the
web server is also a member of the domain).

Your web services can then determine the identity of the authenticated
user with Context.User.Identity.Name.

The other alternatively to consider would be to use WCF or WSE3 or
something to implement some sort of message level security.

I would recommend that you NOT try to implement your own authentication
protocol. It is not easy to get right.

Joe K.

Joe Kaplan-MS MVP Directory Services Programming
Co-author of "The .NET Developer's Guide to Directory Services
"SP" <spspsp@xxxxxxxxxxxx> wrote in message
Hello All,

First of all, let me make it very clear that I do not have any idea
about implementing the windows authentication, so all inputs would be

The scenario :
I have a client - server application. At the moment, the passwords for
the users are stored in a password storage (encrypted). The client app
shows a login dialog, gets the username and password and sends it to
the server where the server verifies it against the password store. I
would like to move to a position where the user does not need to enter
the username and password, If they are logged on to the domain, they
should go straight in. The application is written in C# (client app)
accessing the ASP.NET web services. All of it is done in .NET framework

The way I have figured out so far is as follows :
On the client side,
1) Get the user's identity
2) Send this to the server
On the server side :
3) Validate the user's identity against the active directory
4) If the user is valid, the normal process of using the application

In the process of trying this, I have done the following:
1) Get the user's identity
2) send it to server (the value returned from the above call is string)
so I send it as it is.

On the server side
3) I try and create the SecurityIdentifier object as follows :
System.Security.Principal.SecurityIdentifier sid = new
this call is okay. From here I don't know where to go and how to
validate this agains the active directory. I had a look at AD objects
and it seems the SID should be available in some tokengroups but this
is where I have got completely lost. (On a sidenote :Another thing is,
If I try and use AD searching, I get an error possibly because the call
is run as ASPNET user which does not have access to AD)

Kindly help me in achieving this or if this method is not the correct
way of achieving my goal, advise me accordingly.