I apparently get more than 1 (I think it's 5) public ip addresses from my ISP. They're via DHCP, of course. I currently run Tomato and have also run pfSense and have access to a Juniper SSG5. Is it ...

One is how the computer talks to the internet at large, which is the IP address of your router. That IP address is generally assigned to the router by your internet service provider (ISP); the router, ...