LDAP Authentication using DirectoryEntry

Question

We use to authenticate user on AD using the following DirectoryEntry constructor:

new DirectoryEntry(path, domainName + "\\" + UserName, Password);

It use to work fine until the Domain Controller was changed.

Now to make it work we have to use:

new DirectoryEntry(path,  UserName, Password);

Can anyone please explain difference and why the second method is working now and first is not working?

Note: I am not sure but I think the domain functional level where raised to Server 2008 from Server 2003. Does it make difference?

Answer 1

I don't know exactly why this ever worked :-) and therefore I cannot really explain why the other option works now....

If you work on .NET 3.5, 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? :-)

Cheers, Marc