Originally, the buffers were designed to hold IP datagrams, but they have since been expanded to handle many other protocol PDUs. Unfortunately, the protocols were not added in a layered fashion, and so an SKB (as it now stands) is a confusing hybrid. This "grand tour" was written to help new kernel hackers to better understand their function, and what to do with them. To start the tour, click here. Also included in this introduction is a reference of the functions available to the kernel hacker to manipulate the structures covered in this tour.