Chain Lock

So on Monday night some guy tried to get into my apartment! YIKES!! He was trying to put a key in the lock, so my guess is he was just drunk and confused, but it kind of freaked me out a bit. I was yelling through the door "You've got the wrong house! Please Go Away! You've got the Wrong House!" I know that probably wasn't the smartest thing to say, but it was late and I wasn't thinking straight. So, I bought a chain lock yesterday and went to install it and remembered... my door is made of metal. :( Great... so now I have to figure out if I can install the chain thing on my door anyway or if they make one of these lock things for metal doors.