I have an old HP 1012 connected to my Airport Extreme, and it just printed out a QR code. When I scanned it I got a page telling me I had been hit by the printer troll and that my printer is accessible world-wide. I am not the only victim, as there are already a few other pictures of it floating around the internet (one example: http://imgur.com/a/gTcea). So my question is: is there a way to secure the printer so it can only be used by devices on the local network? And more importantly: is my airport attached external hard drive accessible world-wide also? I think the printer prank is funny and clever but I really don't want anyone to have access to my time machine back-ups (there is a password on the drive but I'm not sure how secure that is). Thanks!