Bpfstat is a non-intrusive way to measure packet loss on open source sensors. Christian SJ Peron has created a tool to monitor network security on FreeBSD 6.0. The tool is available on NetBSD and Netstat. The last version of the tool was released on 6.9a10, 0.9 a9a9, arrived 19 May. I intend to re-engage on Bro to learn what else it can provide in an operational environment. Unfortunately the Bro port does not have a good learning/bro port.”]
Source: https://taosecurity.blogspot.com/2005/09/notes-on-network-security-monitoring.html