5

I need to verify users in the company using only their username - not their password.

So I need a method like this

public bool UserExists(string username)
{ ... }

I am aware of the System.DirectoryServices namespace but don't know where to start.

Any ideas?

There are 80,000+ records so try to bear that in mind.

Thank you.

Edit:

I have done it - my code is: 

private bool UserExists(string userName, string domain)
{
    try
    {
        DirectoryEntry.Exists("WinNT://" + domain + ".[hidden].com/" + userName);
        return true;
    }
    catch (COMException)
    {
        return false;
    }
}

I don't know if it is correct, but it seems to work so far.

Michael's answer has two relevant parts:

Update #2:

I actually used this:

public static bool LoggedOnUserExists()
{
    var domain = new PrincipalContext(ContextType.Domain);

    UserPrincipal foundUser = UserPrincipal.FindByIdentity(domain, IdentityType.SamAccountName, Environment.UserName);

    return foundUser != null;
}
Nobody
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    You should **NOT** use the WinNT provider anymore - it's strictly for backwards compatibility, but it typically doesn't work well in a AD network – marc_s Nov 29 '10 at 15:47

1 Answers1

6

In .NET 3.5 and up, you can use the System.DirectoryServices.AccountManagement namespaces to do this quite simply:

public bool UserExists(string username)
{
   // create your domain context
   using (PrincipalContext domain = new PrincipalContext(ContextType.Domain))
   {
       // find the user
       UserPrincipal foundUser = UserPrincipal.FindByIdentity(domain, IdentityType.Name, username);

       return foundUser != null;
    }
}

This will work with the regular user name John Doe, or alternatively you can use the user's e-mail address (john.doe@company.com), or his distinguished name (CN=John Doe) - see what the IdentityType enumeration has to offer :-)

marc_s
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  • I assume this searches on the current domain? Is there anyway to use this method and specify a domain? – Eddie Oct 24 '12 at 15:18
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    @Eddie: sure - the [`PrincipalContext` has numerous overloaded constructors (perfectly documented on MSDN)](http://msdn.microsoft.com/en-us/library/system.directoryservices.accountmanagement.principalcontext.aspx), which allow you to specify a domain and/or a container in that domain to use for searching – marc_s Oct 24 '12 at 15:26