Your ability to monitor new threats is only as as good as your rules. When the latest Flash zero day starts being exploited actively, you will want to ensure that you get a new rule in place to detect it.
Luckily, Snort has a large user community and a support organization that writes rules and makes them available online. Their rules are broken into three sets: Community, Registered, and Subscription.
As the name implies, the Community set is created by the community and is hosted by http://Snort.org free. The registered and subscription sets are managed, tested, and improved by the company behind Snort. The paid Subscription set gives you access to rule updates 30 days earlier than the registered set, but otherwise the contents are identical.
Having a place to download rules from is great, but having a way to keep them up to date in an automated manner is even better. With Snort, this can be done by the PulledPork tool, which automates the downloads, installation...
