How to hide LAN ip’s from WAN – OK (closed post)

Hi friends. Is it posible to hide my LAN’s ip’s from been seen outside? I have a Cisco 877 K9 connecting my home land to internet. Now, when I connect to some webs they see my public IP but also the local IP’s, as an example in: http://hsi.cablecom.ch/speedtest/
Thanks in advanced for your help.
Best regards.