I'm sorry to see that Rumsfeld's house is right on the street, and he has to put up with people practically looking in his windows. It doesn't seem secure for a man who is a target of terrorists.
How do protestors find out where he lives?
I don't know.
It's easy to find addresses for most people on the internet by using free searches.
For some harder to find people (usually means those with unlisted phone numbers), you can pay about $20 and a more comprehensive search will get you the info.
Still, I would hope that top civilian government officials (DOD, CIA, FBI, etc.) and top generals and admirals would be a lot harder to find.
Seems like there should be some way for these officials to title their houses in the name of a pseudonym so that terrorists and their allies ("peace" protestors) couldn't find them so easily.
Maybe that's what is done, but some neighbors, sellers of the property, realtors, or others in the transaction blow the anonymity? Maybe they do so because they're liberal or more likely just out of excitement (e.g., "you're never guess who my new neighbor is! Secretary of Secret Projects, Fearless Leader himself" (see photo below).