C# Check if Current Logged on user is Admin (Remote Machine)

Question

I know there are several discussions about this subject but none really answer my exact question. I'm looking for a method that will check Remotely if a current logged on user has Admin rights. Whether he's a member of the local built in "administrators" group of the machine or member of a nested group inside "Administrators", such as "Domain Admins" for example. I found couple of methods but each provides only half solution.

Method #1 (work remotely but only checks the local "Administrators" Group):

private bool isAdmin()
{
    ArrayList mem2 = new ArrayList();
    string hostName = basicinfomodel.Loggedusername; //a username I get from another class
    try
    {
        using (DirectoryEntry machine = new DirectoryEntry("WinNT://" + mycomputer.myComputerName)) // remote computer that I get from another class
        {
            //get local admin group
            using (DirectoryEntry group = machine.Children.Find("Administrators", "Group"))
            {
                //get all members of local admin group
                object members = group.Invoke("Members", null);
                foreach (object member in (IEnumerable)members)
                {
                    //get account name
                    string accountName = new DirectoryEntry(member).Name;
                    mem2.Add(new DirectoryEntry(member).Name);
                }
            }
        }
    }
    catch (Exception ex)
    {
        // catch
    }

    if (mem2.Contains(hostName.ToUpper()) || mem2.Contains(hostName.ToLower()))
        return true;
    else
        return false;
}

Method #2 (check both local and domain admin privileges but not working remotely)

static bool isAdmin()
{
    WindowsIdentity User = new WindowsIdentity(@"user01");
    WindowsPrincipal princ = new WindowsPrincipal(User);
    return princ.IsInRole(WindowsBuiltInRole.Administrator);
}

so as I said, I did not find any Method that will answer both needs.

1. check if the user truly has admin rights
2. do it remotely

thanks for the help!

Answer 1

Well, I think I found a way to do that, I'm sharing in case other people would want to use it. I played with couple of methods I found and created the following (seems to be working)

static bool isAdmin(string username, string machinename)
{
    using (PrincipalContext ctxMacine = new PrincipalContext(ContextType.Machine, machinename))
    {
        using (PrincipalContext ctxDomain = new PrincipalContext(ContextType.Domain))
        {
            UserPrincipal up = UserPrincipal.FindByIdentity(ctxDomain, IdentityType.SamAccountName, username);
            GroupPrincipal gp = GroupPrincipal.FindByIdentity(ctxMacine, "Administrators");

            foreach (UserPrincipal usr in gp.GetMembers(true))
            {
                if (up != null)
                {
                    if (up.SamAccountName.ToUpper() == usr.SamAccountName.ToUpper())
                    {
                        return true;
                    }
                }
            }
        }
    }
    return false;
}

Note
This is a naive implementation, you should validate your code, checking for null's and handle exceptions.