KEDR is a framework to facilitate dynamic analysis of kernel modules in Linux ("KEDR" is an acronym for "KErnel-mode Drivers in Runtime"). KEDR allows you to intercept the calls that a kernel module makes to the functions exported by other modules and by the kernel proper. The tools provided by the framework can record the arguments and return values of these functions to a trace, perform fault simulation according to user-defined scenarios, and check the kernel modules for memory leaks and some other kinds of problems. Custom data collection and analysis tools for the Linux kernel can also be built on top of KEDR framework.
otonat is a 1:1 NAT implementation for FreeBSD. Unlike other solutions that keep state for individual user connections even for 1:1 NAT, otonat is completely stateless as far as user connections are concerned. This allows it to scale much better and provide protection against misbehaving clients that may consume a lot of server memory by opening too many connections.