That's a good idea, but it falls down the first time someone in the crowd starts downloading cp. Instead of having one, or a few, people being traced to their

That's a good idea, but it falls down the first time someone in the crowd starts downloading cp. Instead of having one, or a few, people being traced to their IP and investigated for cp, you now have 1,000 people under suspicion. You can protect users by ensuring that the box doesn't log any information about them, but then the box's admin is the one being held responsible.