Nobody from outside the system that has no login will be able to get to /tmp. The trouble with a lot of these shell providers is finding anonymous ftp space and with a quota of 5 mb, how do you split the upload/download in 5 meg chunks to delete from the server, and piece the files back together, upload one, other person downloads it, delete from server, upload again, and so on, but how that's done and files pieced back together is something I don't think linux does.
