Since we're assuming that not everyone already has a wired or wireless CF network card, this entire section covers the basics of establishing simple networking between your Z and your Linux host via the USB cradle, which everyone should be able to do. Clearly, if you have a network card, most of this section doesn't apply to you.
Note that this entire section covers only basic USB networking, just to the extent of getting your Z on the net, being able to ping, log in and copy files back and forth. More advanced networking issues, such as setting up VNC, NFS and the like is covered in a later chapter.
If you want your configuration to match exactly what follows over the next several pages, make sure you start with either your Z's cradle not plugged into the host's USB port, or plugged in but the Z not turned on yet.