Using temporary IPs in the cloud considered harmful

32 points

16 years ago

Here's an amusing hobby: 1. Start Amazon EC2 instances (or any other cloud service) 2. Use something like honeyd to listen on all ports 3. Wait for random activity associated with the previous owner of the EC2 instance to start flowing in.

I stumbled across this by accident after getting flooded by connections from apps.facebook.com which seems to be trying to interact with a Facebook app that was previously hosted on an IP which I'm now using. Presumably the previous owner of an EC2 instance had a DNS name that resolved to this IP and didn't see the risks of doing so. Remember: the Amazon public IPs are temporary and will be reassigned once the EC2 instance stops or dies.

For the sake of your users' privacy and security, use Elastic IPs. Even if the instance dies, the Elastic IP still belongs to you and won't be accidentally be reassigned to someone else. When you start up a new instance you can have the Elastic IP assigned to the new instance using ec2-associate-address.

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