I'm following this guide CoreOS + Kubernetes - Step By Step in a VirtualBox VM's. Everything working until i need expose services as extenal_ips to my host. When a create my guestbook-service.json a external ip should be created, like the image bellow.

NAME        CLUSTER_IP       EXTERNAL_IP    PORT(S)      SELECTOR
guestbook   10.0.207.218     146.148.81.8   3000/TCP     app=guestbook

But instead i'm having the following

NAME        CLUSTER_IP       EXTERNAL_IP    PORT(S)      SELECTOR
guestbook   10.0.207.218                    3000/TCP     app=guestbook

My VM's have a Bridge Network and a NAT Network configured, and CoreOS with static IP's.

Thanks.