Apply Auth Middleware to All Laravel Routes

You can group all your authenticated routes like following, laravel provides a default middleware for auth and guest users

Route::group(['middleware' => ['auth']], function () { 
    Route::get('home', 'HomeController@index');
    Route::post('save-user', 'UserController@saveUser');
    Route::put('edit-user', 'UserController@editUser');
});

The above route names are just made up, please follow a proper naming convention for your routes and controllers. Also read about middlewares over here and about routing over here

You can add middleware to your whole web.php route file by adding the middleware to your routes mapping in RouteServiceProvider.

Go to app/Providers/RouteServiceProvider.php and in mapWebRoutes(), change middleware('web') to middleware(['web', 'auth']):

protected function mapWebRoutes()
{
    Route::middleware(['web', 'auth'])
         ->namespace($this->namespace)
         ->group(base_path('routes/web.php'));
}

This is (not?) totally unrelated but here's an example of a clean way to handle a lot of route files instead of throwing all your routes into a single web.php file:

Create a new method mapAdminRoutes():

protected function mapAdminRoutes()
{
    Route::middleware(['web', 'auth:admin'])
        ->namespace('App\Http\Controllers\Admin')
        ->name('admin.')
        ->group(base_path('routes/admin.php'));
}

Map it:

public function map()
{
    $this->mapWebRoutes();
    $this->mapAdminRoutes(); // <-- add this
    ...
}

Create an admin.php file in your routes folder, then create your routes for Admin:

<?php

use Illuminate\Support\Facades\Route;

// This route's name will be 'admin.dashboard'
Route::get('dashboard', 'DashboardController@dashboard')->name('dashboard');

// This route's name will be 'admin.example'
Route::get('example', 'ExampleController@example')->name('example');

...

Now you can configure everything in 1 place, like prefix, name, middleware and namespace.

Check php artisan route:list to see the results :)

you can apply middlewares in the routes.php file, what you need to do is to put all your routes on a group, and add the middleware 'auth' ( except the Auth::routes() which are already configured), for example :

Route::middleware(['first', 'second'])->group(function () {
    Route::get('/', function () {
        // Uses first & second Middleware
    });

    Route::get('user/profile', function () {
        // Uses first & second Middleware
    });
});

more information can be found in the docs: https://laravel.com/docs/5.7/routing#route-group-middleware