How to provide DirectoryEntry.Exists with credentials?

Question

This morning I discovered a nice method (DirectoryEntry.Exists), that should be able to check whether an Active Directory object exists on the server. So I tried with a simple:

if (DirectoryEntry.Exists(path)) {}

Of course it lacks any overloads to provide credentials with it. Because, if credentials are not provided I get this Exception:

Logon failure: unknown user name or bad password. (System.DirectoryServices.DirectoryServicesCOMException)

Is there any other option that gives me the possibility to authenticate my code at the AD server? Or to check the existence of an object?

Answer 1

In this case you can't use the static method Exists as you said :

DirectoryEntry directoryEntry = new DirectoryEntry(path);
directoryEntry.Username = "username";
directoryEntry.Password = "password";

bool exists = false;
// Validate with Guid
try
{
    var tmp = directoryEntry.Guid;
    exists = true;
}
catch (COMException)
{
   exists = false; 
}

Answer 2

I know this is an old question, but the source code is now available so you can just Steal and Modify™ to make a version that accepts credentials:

public static bool Exists(string path, string username, string password)
{
    DirectoryEntry entry = new DirectoryEntry(path, username, password);
    try
    {
        _ = entry.NativeObject;       // throws exceptions (possibly can break applications)
        return true;
    }
    catch (System.Runtime.InteropServices.COMException e)
    {
        if (e.ErrorCode == unchecked((int)0x80072030) ||
             e.ErrorCode == unchecked((int)0x80070003) ||   // ERROR_DS_NO_SUCH_OBJECT and path not found (not found in strict sense)
             e.ErrorCode == unchecked((int)0x800708AC))     // Group name could not be found
            return false;
        throw;
    }
    finally
    {
        entry.Dispose();
    }
}

The one change you must make is changing the use of Bind, since that's an internal method and can't be used by mere mortals like us. Instead, I just get the NativeObject property, which calls Bind() for us.

You can use that like this:

var ouExists = Exists("LDAP://hadoop.com/OU=Students,DC=hadoop,DC=com", "username", "password");

Answer 3

There is no way to do this and I have written a connect issue to hopefully resolve it.

DirectoryEntry.Exists Does Not Accept Credentials