Linux Firewalls, Third Edition

A Quick Look Around the Kernel

I'd like to introduce the kernel. If this is the first time you've met, say hello and treat it nicely. The kernel is the piece of software responsible for talking to the hardware and creating the background environment within which programs are run. You usually don't encounter the kernel until you have to load hardware or need to recompile it for additional features or security updates. Most Linux vendors now include modular kernels along with their regular updates, thus greatly reducing the number of people who compile their own kernel, or roll their own kernel as it is sometimes called.

What'd You Call That?

Before I go too far, I should get some terms out of the way in relation to the kernel. First is differentiation ...