I have an external HDD with data I need to share at my university. Even though I do have a backup, I don't like to get any viruses or trojans from others computers and I don't want anybody to change the data without me knowing. So what I need is to somehow write protect this drive so it can only be read, but not written on. The problem is that this has to work over several OSes, this drive will go on Windows (everything after XP), Linux and OSX (with Tuxera NTFS drivers) as well as getting connected to a USB network hub. Any idea how to do this of if it is even possible? The drive is formatted with NTFS since it's the only file system that works over several computers and on the hub.