Fun and Games with FreeBSD Kernel Modules
rootkit techniques for the freebsd kernel
Hooking Filters for Fun and Profit: PFIL_HOOKS
tutorial (with example code) on using pfil hooks in freebsd to hook into the networking stack
FreeBSD Device Driver Template/Skeleton (Kernel Module)
example of creating a /dev device in freebsd as a kernel module
FreeBSD - Tree macro tutorial
Tutorial on using Trees in the FreeBSD kernel