Example of Laravel 5 Middleware - http://slashnode.com/definitive-laravel-4-to-laravel-5-migration-guide/

GuestMiddleware.php

<?php 

/** in app/Http/Middleware/GuestMiddleware.php */

    class GuestMiddleware implements Middleware
    {
        public function handle($request, Closure $next)
        {
            if (\Auth::check()) {
                return new RedirectResponse(url('/'));
            }
    
            return $next($request);
        }
    }



/** in app/Http/Kernel.php */

    /** ...etc */
    protected $routeMiddleware = [
        'guest' => 'App\Http\Middleware\GuestMiddleware',
    ];
    /** ...etc */



/** in app/Http/routes.php */

    get('auth/login', ['middleware' => 'guest' 'uses' => 'AuthController@getLogin']);