Use ActionFilterAttribute to check user logging

public class CheckLoginAttribute : ActionFilterAttribute
{
public CheckLoginAttribute()
{

}
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
if (filterContext.HttpContext.Session["User"] == null)
{
filterContext.Result = new RedirectResult("/Account/LogOn");
return;
}
base.OnActionExecuting(filterContext);
}

}

public class HomeController : Controller
{
public ActionResult Index()
{
ViewBag.Message = "Welcome to ASP.NET MVC!";

return View();
}
[CheckLogin]
public ActionResult About()
{
return View();
}
}