backend/app/Http/Middleware/TokenMiddleware.php

<?php
/**
 * Created by PhpStorm.
 * User: robin
 * Date: 11/24/15
 * Time: 1:20 AM
 */

namespace App\Http\Middleware;

use Closure;
use Illuminate\Http\Request;

class TokenMiddleware
{
    /**
     * @param $request Request
     * @param Closure $next
     * @return null|string
     */
    public function handle($request, Closure $next)
    {
        if ($request->headers->get("X-Token") != getenv("TOKEN")) {
            abort(401);
        }
        return $next($request);
    }
}