A user generally can t mask the system s IP address the string of numbers such as 123.12.456.78 that identifies it on the Internet. While online, every PC has an IP address. In dial-up connections, the numbers generally are assigned dynamically, which means the address changes every time the user dials up a provider. That in itself is a protection. But embedded inside every network adapter card is a MAC, or media access control, address that doesn t change.
Modems don t identify themselves with such a number.
But many modern hotel rooms are being outfitted with high-bandwidth Internet connections that require an Ethernet card. So even if your IP address changes, your MAC address won t. All three of the tested firewalls blocked exposure of the MAC address and any shared resources. For the most part, all were effective at fending off probes. That still isn t enough.