Just as a follow-up to this thread for those that are interested. I went ahead and changed the default Calibre content server port from 8080 to a rather non-standard port number. After running 24 hours on the new port number, I have not had a single hit from these nefarious actors (I was getting several an hour prior to the change). Hopefully this will keep these annoying hackers away from the content server for a while.
