In Laravel-5 localhost:8000 not working when in offline in ubuntu

With this command

php artisan serve

when my Ubuntu 14.04 is connected with network/online. It's ok. And shows

Laravel development server started on http://localhost:8000/

But when offline. Its show......

Laravel development server started on http://localhost:8000/ [Sun Dec 27 19:54:34 2015] PHP Warning: Unknown: php_network_getaddresses: getaddrinfo failed: Name or service not known in Unknown on line 0 [Sun Dec 27 19:54:34 2015] Failed to listen on localhost:8000 (reason: php_network_getaddresses: getaddrinfo failed: Name or service not known)

via Chebli Mohamed