|Manage Security / Best Practices|
Because all instances are based on images, creating a secure image helps to create secure instances. This topic lists best practices that will add additional security during image creation. As a general rule, harden your images similar to how you would harden your physical servers.
sync && /sbin/sysctl vm.drop_caches=3 && swapoff -a && swapon -a
After locking down the image using the steps above, additional steps can be done to further secure instances started from that image. For example, restrict access to the instance by allowing only trusted hosts or networks to access ports on your instances. You can control access to instances using euca-authorize and euca-revoke.
Consider creating one security group that allows external logins and keep the remainder of your instances in a group that does not allow external logins. Review the rules in your security groups regularly, and ensure that you apply the principle of least privilege: only open up permissions as they are required. Use different security groups to deal with instances that have different security requirements.