<authentication mode="Forms">
      <forms loginUrl="~/Account/Login" timeout="2880" />
    </authentication>

        [HttpPost]
        [AllowAnonymous]
        public ActionResult Login(AccountModel model, String returnUrl)
        {
            if (ModelState.IsValid)
            {
                //AuthProvider проверяет пароль в БД
                AuthProvider.AuthProvider prov = new AuthProvider.AuthProvider();
                if (prov.AuthenticationIsValid(model.Login, model.Password))
                {
                    FormsAuthentication.SetAuthCookie(model.Login, false);
                    return Redirect(Url.Action("Index", "Operator"));
                }

                ModelState.AddModelError("", "Incorrect username or password");
            }

            return View();
        }