Quick Start Guide for using Sourcefire Snort on Amazon EC2
www.snort.org/assets/144/Snort_EC2_QuickStart.pdf
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
Sourcefire Snort is now available for Amazon Elastic Computing Cloud (EC2) users. Amazon Web Services (AWS) account holders can subscribe to a Sourcefire Snort Amazon Machine Image (AMI) for EC2 to protect their cloud.