Laravel认证登录路由

我使用的是laravel 5.1，用户登录后，login和register的url仍然可以被用户访问。

我目前实现的路由如下:

<?php
$s = 'public.';
Route::get('/',         ['as' => $s . 'home',   'uses' => 'PagesController@getHome']);
$a = 'auth.';
Route::get('/login',            [ 'as' => $a . 'login',  'uses' => 'Auth'AuthController@getLogin']);
Route::post('/login',           ['as' => $a . 'login-post',     'uses' => 'Auth'AuthController@postLogin']);
Route::get('/register',         ['as' => $a . 'register',       'uses' => 'Auth'AuthController@getRegister']);
Route::post('/register',        ['as' => $a . 'register-post',  'uses' => 'Auth'AuthController@postRegister']);
Route::get('/password',         ['as' => $a . 'password',       'uses' => 'Auth'PasswordResetController@getPasswordReset']);
Route::post('/password',        ['as' => $a . 'password-post',  'uses' => 'Auth'PasswordResetController@postPasswordReset']);
Route::get('/password/{token}', ['as' => $a . 'reset',          'uses' => 'Auth'PasswordResetController@getPasswordResetForm']);
Route::post('/password/{token}',['as' => $a . 'reset-post',     'uses' => 'Auth'PasswordResetController@postPasswordResetForm']);
$s = 'social.';
Route::get('/social/redirect/{provider}',   ['as' => $s . 'redirect',   'uses' => 'Auth'AuthController@getSocialRedirect']);
Route::get('/social/handle/{provider}',     ['as' => $s . 'handle',     'uses' => 'Auth'AuthController@getSocialHandle']);
Route::group(['prefix' => 'admin', 'middleware' => 'auth:administrator'], function()
{
    $a = 'admin.';
    Route::get('/', ['as' => $a . 'home', 'uses' => 'AdminController@getHome']);
});
Route::group(['prefix' => 'user', 'middleware' => 'auth:user'], function()
{
    $a = 'user.';
    Route::get('/', ['as' => $a . 'home', 'uses' => 'UserController@getHome']);
});
Route::group(['middleware' => 'auth:all'], function()
{
    $a = 'authenticated.';
    Route::get('/logout', ['as' => $a . 'logout', 'uses' => 'Auth'AuthController@getLogout']);
});

我尝试了以下方法，但没有成功:

Route::get('/login',            ['before'=> 'auth', 'as' => $a . 'login',  'uses' => 'Auth'AuthController@getLogin']);

谢谢! !