后台不能在一个浏览器登陆，下面简单配置下即可解决这个问题。

设置路由如下：

<?php

/**
 * 后台路由，从Illuminate\Routing\Router控制器的auth()方法中复制过来的
 */
Route::namespace('Admin')->group(function () {
    // Authentication Routes...
    Route::get('login', 'Auth\LoginController@showLoginForm')->name('admin.login');
    Route::post('login', 'Auth\LoginController@login');
    Route::post('logout', 'Auth\LoginController@logout')->name('admin.logout');

// Registration Routes...
    Route::get('register', 'Auth\RegisterController@showRegistrationForm')->name('admin.register');
    Route::post('register', 'Auth\RegisterController@register');

// Password Reset Routes...
    Route::get('password/reset', 'Auth\ForgotPasswordController@showLinkRequestForm')->name('admin.password.request');
    Route::post('password/email', 'Auth\ForgotPasswordController@sendResetLinkEmail')->name('admin.password.email');
    Route::get('password/reset/{token}', 'Auth\ResetPasswordController@showResetForm')->name('admin.password.reset');
    Route::post('password/reset', 'Auth\ResetPasswordController@reset');

    Route::middleware(["auth:admin"])->group(function () {
        Route::get('/', 'AdminController@index')->name('admin');
    });
});

<?php

/**
 * 前台路由，从Illuminate\Routing\Router控制器的auth()方法中复制过来的
 */
Route::get('/', function () {
    return view('welcome');
});

// Authentication Routes...
Route::get('login', 'Auth\LoginController@showLoginForm')->name('login');
Route::post('login', 'Auth\LoginController@login');
Route::post('logout', 'Auth\LoginController@logout')->name('logout');

// Registration Routes...
Route::get('register', 'Auth\RegisterController@showRegistrationForm')->name('register');
Route::post('register', 'Auth\RegisterController@register');

// Password Reset Routes...
Route::get('password/reset', 'Auth\ForgotPasswordController@showLinkRequestForm')->name('password.request');
Route::post('password/email', 'Auth\ForgotPasswordController@sendResetLinkEmail')->name('password.email');
Route::get('password/reset/{token}', 'Auth\ResetPasswordController@showResetForm')->name('password.reset');
Route::post('password/reset', 'Auth\ResetPasswordController@reset');

Route::middleware(["auth:web"])->group(function () {
    Route::get('/home', 'HomeController@index')->name('home');
});

设置 config/auth.php：

<?php

return [

    /*
    |--------------------------------------------------------------------------
    | Authentication Defaults
    |--------------------------------------------------------------------------
    |
    | This option controls the default authentication "guard" and password
    | reset options for your application. You may change these defaults
    | as required, but they're a perfect start for most applications.
    |
    */

    'defaults' => [
        'guard' => 'web',
        'passwords' => 'users',
    ],

    /*
    |--------------------------------------------------------------------------
    | Authentication Guards
    |--------------------------------------------------------------------------
    |
    | Next, you may define every authentication guard for your application.
    | Of course, a great default configuration has been defined for you
    | here which uses session storage and the Eloquent user provider.
    |
    | All authentication drivers have a user provider. This defines how the
    | users are actually retrieved out of your database or other storage
    | mechanisms used by this application to persist your user's data.
    |
    | Supported: "session", "token"
    |
    */

    'guards' => [
        'web' => [
            'driver' => 'session',
            'provider' => 'users',
        ],

        'admin' => [
            'driver' => 'session',
            'provider' => 'admins',
        ],

        'api' => [
            'driver' => 'token',
            'provider' => 'users',
        ],
    ],

    /*
    |--------------------------------------------------------------------------
    | User Providers
    |--------------------------------------------------------------------------
    |
    | All authentication drivers have a user provider. This defines how the
    | users are actually retrieved out of your database or other storage
    | mechanisms used by this application to persist your user's data.
    |
    | If you have multiple user tables or models you may configure multiple
    | sources which represent each model / table. These sources may then
    | be assigned to any extra authentication guards you have defined.
    |
    | Supported: "database", "eloquent"
    |
    */

    'providers' => [
        'users' => [
            'driver' => 'eloquent',
            'model' => App\User::class,
        ],

        'admins' => [
            'driver' => 'eloquent',
            'model' => \App\Models\Admin::class,
        ],
        // 'users' => [
        //     'driver' => 'database',
        //     'table' => 'users',
        // ],
    ],

    /*
    |--------------------------------------------------------------------------
    | Resetting Passwords
    |--------------------------------------------------------------------------
    |
    | You may specify multiple password reset configurations if you have more
    | than one user table or model in the application and you want to have
    | separate password reset settings based on the specific user types.
    |
    | The expire time is the number of minutes that the reset token should be
    | considered valid. This security feature keeps tokens short-lived so
    | they have less time to be guessed. You may change this as needed.
    |
    */

    'passwords' => [
        'users' => [
            'provider' => 'users',
            'table' => 'password_resets',
            'expire' => 60,
        ],
    ],

];

为后台所有路由设置前缀 App\Providers\RouteServiceProvider：

<?php

namespace App\Providers;

use Illuminate\Support\Facades\Route;
use Illuminate\Foundation\Support\Providers\RouteServiceProvider as ServiceProvider;

class RouteServiceProvider extends ServiceProvider
{
    /**
     * This namespace is applied to your controller routes.
     *
     * In addition, it is set as the URL generator's root namespace.
     *
     * @var string
     */
    protected $namespace = 'App\Http\Controllers';

    /**
     * Define your route model bindings, pattern filters, etc.
     *
     * @return void
     */
    public function boot()
    {
        //

        parent::boot();
    }

    /**
     * Define the routes for the application.
     *
     * @return void
     */
    public function map()
    {
        $this->mapApiRoutes();

        $this->mapWebRoutes();

        // 为后台路由添加前缀
        $this->mapAdminRoutes();

        //
    }

    /**
     * Define the "web" routes for the application.
     *
     * These routes all receive session state, CSRF protection, etc.
     *
     * @return void
     */
    protected function mapWebRoutes()
    {
        Route::middleware('web')
             ->namespace($this->namespace)
             ->group(base_path('routes/web.php'));
    }

    /**
     * Define the "api" routes for the application.
     *
     * These routes are typically stateless.
     *
     * @return void
     */
    protected function mapApiRoutes()
    {
        Route::prefix('api')
             ->middleware('api')
             ->namespace($this->namespace)
             ->group(base_path('routes/api.php'));
    }

    /**
     * 加入后台路由
     */
    protected function mapAdminRoutes()
    {
        Route::prefix('admin')
            ->middleware('web')
            ->namespace($this->namespace)
            ->group(base_path('routes/admin.php'));
    }
}

后台 App\Http\Controllers\Admin\Auth\LoginController 如下：

<?php

namespace App\Http\Controllers\Admin\Auth;

use App\Http\Controllers\Controller;
use Illuminate\Foundation\Auth\AuthenticatesUsers;
use Illuminate\Support\Facades\Auth;

class LoginController extends Controller
{
    /*
    |--------------------------------------------------------------------------
    | Login Controller
    |--------------------------------------------------------------------------
    |
    | This controller handles authenticating users for the application and
    | redirecting them to your home screen. The controller uses a trait
    | to conveniently provide its functionality to your applications.
    |
    */

    use AuthenticatesUsers;

    /**
     * Where to redirect users after login.
     *
     * @var string
     */
    protected $redirectTo = '/admin';

    /**
     * Create a new controller instance.
     *
     * @return void
     */
    public function __construct()
    {
        $this->middleware('guest:admin')->except('logout');
    }

    public function showLoginForm()
    {
        return view('admin.auth.login');
    }

    /**
     * Get the guard to be used during authentication.
     *
     * @return \Illuminate\Contracts\Auth\StatefulGuard
     */
    protected function guard()
    {
        return Auth::guard('admin');
    }
}

前台 App\Http\Controllers\Auth\LoginController 如下：

<?php

namespace App\Http\Controllers\Auth;

use App\Http\Controllers\Controller;
use Illuminate\Foundation\Auth\AuthenticatesUsers;

class LoginController extends Controller
{
    /*
    |--------------------------------------------------------------------------
    | Login Controller
    |--------------------------------------------------------------------------
    |
    | This controller handles authenticating users for the application and
    | redirecting them to your home screen. The controller uses a trait
    | to conveniently provide its functionality to your applications.
    |
    */

    use AuthenticatesUsers;

    /**
     * Where to redirect users after login.
     *
     * @var string
     */
    protected $redirectTo = '/home';

    /**
     * Create a new controller instance.
     *
     * @return void
     */
    public function __construct()
    {
        $this->middleware('guest:web')->except('logout');
    }
}

App\Http\Middleware\RedirectIfAuthenticated 中间件修改 (防止二次登录，与LoginController中的$this->middleware('guest:web')->except('logout') 这里相呼应，除了退出登录，只要访问类似登录，注册，找回密码的路由时候，都检查一遍用户是否登录，登陆了直接跳到登录页，未登录走auth中间件)：

<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Support\Facades\Auth;

class RedirectIfAuthenticated
{
    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @param  string|null  $guard
     * @return mixed
     */
    public function handle($request, Closure $next, $guard = null)
    {
        if ($guard == 'web' && Auth::guard($guard)->check()) {
            return redirect('/home');
        }

        if ($guard == 'admin' && Auth::guard($guard)->check()) {
            return redirect('/admin');
        }

        return $next($request);
    }
}

效果：

原文地址：https://laravel-china.org/articles/21683