If you followed all the examples in this book, you most probably have done your experiments and also your own research on a jailbroken iPhone. You have that in common with a large number of people, because nearly all iPhone security research is performed on jailbroken devices. However, for the majority of people, including the security community and iPhone security researchers, the inner workings of a jailbreak are completely unknown. Many people think of jailbreaks as black boxes that work — like magic — after they click a jailbreak button in their tool of choice. This is often because knowing the inner workings of a jailbreak is not required for the development of things they are working on, for example userland exploits.
But if you've ever wondered how the jailbreaking process works internally, this chapter will answer a lot of your questions.
After a short introduction of the different jailbreak types, we use the redsn0w jailbreak as an example, guiding you step by step through the jailbreak process happening on your device. This chapter also introduces you to the inner workings of the kernel patches applied by the jailbreak, so that you can learn which of these patches are actually required and which are optional.
People jailbreak their iOS devices for many reasons. Some of them want an open platform for which they can develop software, others like the idea of having total control over their devices, some require jailbreaks to install ...