Login anonymous user with username and password by code on a SharePoint main page

Question

I have a custom usercontrol to logon users.

My Authentication setting:

• Authentication Type: Windows

• Enabled anonymous access

• IIS Authentication Setting: Basic authentication

Now is the question how I can logon an anonymous user when he type a username + password and click login in the custom user control?

My current code in a IHttpModul:

IntPtr token = IntPtr.Zero;

                            bool result = User.LogonUser(userName,
                                                    host,
                                                    userPassword,
                                                    User.LogonSessionType.NetworkCleartext,
                                                    User.LogonProvider.Default,
                                                    out token);

                            if (result)
                            {
                                WindowsIdentity identity = new WindowsIdentity(token, "Basic");
                                WindowsPrincipal principal = new WindowsPrincipal(identity);

                                HttpContext.Current.User = principal;
                            }

But I get a login windows from internet explorer.

But the strang thing is when I click on the cancel button I am loged in into SharePoint!

Any suggestions?