Locking down the Google SiteMaps

So only google and ourself can access the file

[chesworth]

We want to put a Google sitemaps file on some of our websites however if we simply uploaded this file it would allow everyone to see every url and site we want indexed.

We only want ourselves and Google to be able to view this file.

Is there anyway we could lock it? We have thought of a IP Address block which would be easy to do, if we knew Googles SiteMaps servers IP range.

Does anyone know all of Googles IP ranges?

[ChadSEO]

I'm sure it's not all-inclusive, but all my sitemaps have been downloaded by 66.249.65.X and 66.249.66.X