Ah ok great, I understand. So just to confirm, information regarding a network's external IP address is not broadcasted (unencrypted at least)?
My reason for this thread was solely curiosity. I live in Ireland and one of the country's main ISP's is called "eircom". I noticed over the past year that the vast majority of people with this ISP have the same router, namely the "ZyXEL P-660" router. After doing a quick google for zyxel router exploits, I came across this framework http://www.routerpwn.com/#zyxel
where a few, fairly significant exploits are described, although they obviously rely on the IP address of the router, which in turn led me to the question.
So say one was to launch kismet for example, and in turn reveal a WPA secured wireless network possessing this Zyxel router, if they obtained the external IP address, they could execute one of these exploits and acquire access to the router and thus the WPA key...