Laravel: Authenticate User From Another Web Application

I'm newest with laravel. Here is the thing. I already have custom web application with my own auth service. I already have table of users and it's works for a long time as well. Currently, I want to add a laravel app into my custom project. I just placed the laravel folder into the root directory of my application (now I can get access into the laravel app by this query http://ift.tt/2e08jLh). So, I want to get authenticated in the laravel application when login into the main application. What can I do? Currently, I want to authenticate user inside my old project and then just "told" laravel that everything ok and those user authenticated. I'm using Laravel 5.1 Thanks.

via Chebli Mohamed