@Vane:
Thanks for the reply Bill, for current releases is it not possible to add a simple option to block hosts that trigger drop or reject rules instead of alert? Sorry if I am being redundant but I assume there is a way to distinguish between an alert and drop rule even though the packet doesn't drop.
For Suricata I think it would be possible, but there would be a potentially big user learning curve. Let me explain. Many users of Suricata and Snort on pfSense are not full-time IDS/IPS folks (this is my opinion based on some of the questions asked here occasionally and is not meant as a slight … ;) ). They sort of expect to install the package, enable some rules and turn on blocking and have it start blocking hosts. Having the default state be alerting only with blocking only possible by changing the rule actions would be a big paradigm shift.
None of the popular rules packages (Snort VRT and Emerging Threats) provide rules with any kind of action keyword other than ALERT. So if the package were changed to truly just "alert" on ALERT action keywords and only "block" on DROP action keywords, then users would have to modify their rules to achieve the same type of auto-blocking they get today.
Now what I have thought about is an option to switch modes between what I call the "current legacy mode" and a mode such as what you describe where ALERT means alert and only DROP means block. Doing this in Suricata would be easy. The Snort package may be more difficult, though. I took a quick look into the API code used by the blocking plugin, and it was not readily apparent that the rule "action" was provided in the alert data seen by the Snort blocking plugin. I need to investigate that more deeply to see if I overlooked something. The Snort code is not well commented in this particular area.
Bill