When I look inside the ADSL modem, it says my public IP is 100.113.191.169 but when I use web sites such as whatismyip.com, etc ,, my IP seems like 78.190.10xxxx.xxxxxx . I think ISP has a shortage of IP addresses . Also it is interesting that many people share this 78.190.xx.xxx IP address, so if there happens a legal issue, how will the authorities know which person did evil things?