Fireflier is a firewall tool, which is built on top of the iptables framework. You can create rules based on single incoming network packets or simply allow/deny single packets to pass. This project is discontinued. (see homepage)
OSA::net project main goal is to create an extensible, scalable framework for management of security related devices in middle-sized and large computer networks.
Nubric (Near-real-time user behaviour and resource interaction control) is a framework for security and authentication-related modules written in Java. Its origin focus lies on network monitoring, dynamic, transparent firewalling and traffic control.