C# – ADAM authentication w/ ADAM user and simple bind

active-directoryadamauthenticationc

I've followed the ADAM Step by Step Guide from Microsoft and setup an ADAM instance on my local machine. I'm attempting to authenticate using the "Mary Baker" account, but every time I get a COM exception on the if (entry.Guid != null) line below. The exception states that there's an unknown user name or bad password.

However, I can use the ldp utility to connect to ADAM and successfully perform a simple bind – so I know that the user name both exists, and I have the correct password.

Additionally, I have set the msDS-UserAccountDisabled property on the user to false, and added the user to both the Administrators and Readers roles.

Any thoughts?

    path = "LDAP://localhost:50000/O=Microsoft,c=US";
    userId = "CN=Mary Baker,OU=ADAM users,";
    password = "Mary@101";

    DirectoryEntry entry = new DirectoryEntry(path, userId, password, AuthenticationTypes.None);
    if (entry.Guid != null)
        LoadWelcomeScreen();

Thanks.

Best Answer

ADAM stores the unique identifier for a user in the displayName attribute of the user class. They need to be unique in the ADAM instance for the user to authenticate. If two users both had their displayName attribute set to 'jsmith' then neither user could authenticate in ADAM.

Use the ldp utility to query the displayName for Mary Baker. It could be something like 'mbaker'. Use that value as the userId in the given code.

This is the style that Microsoft tends to use in their examples.

It appears that the guidance in this area may have changed, as StyleCop now enforces the use of the C# specific aliases.

C# – Validate a username and password against Active Directory

If you work on .NET 3.5 or newer, you can use the System.DirectoryServices.AccountManagement namespace and easily verify your credentials:

// create a "principal context" - e.g. your domain (could be machine, too)
using(PrincipalContext pc = new PrincipalContext(ContextType.Domain, "YOURDOMAIN"))
{
    // validate the credentials
    bool isValid = pc.ValidateCredentials("myuser", "mypassword");
}

It's simple, it's reliable, it's 100% C# managed code on your end - what more can you ask for? :-)

Read all about it here:

Update:

As outlined in this other SO question (and its answers), there is an issue with this call possibly returning True for old passwords of a user. Just be aware of this behavior and don't be too surprised if this happens :-) (thanks to @MikeGledhill for pointing this out!)

Best Answer

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This is the style that Microsoft tends to use in their examples.

C# – Validate a username and password against Active Directory

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