Mknod

Credit
iPhone Dev Team

Exploit
This exploit, also known as OktoPrep, after the name of the package used to prepare it, was the standard 1.1.2 jailbreak. Like Symlinks and Soft Upgrade, this was an update jailbreak that required the user to upgrade from an older to a newer version of the OS to achieve the jailbreak. Essentially, the user would jailbreak 1.1.1 through the libTiff exploit, install the OktoPrep package in Installer, and update to 1.1.2 in iTunes, and use the iPhone Dev Team's jailbreak utility, written by planetbeing.

The OktoPrep package created a node for the operating system, essentially copying /dev/rdisk0s1 to /private/var/root/Media/rdisk0s1. Since the 1.1.2 ramdisk did not check for this, it would remain in 1.1.2, and the operating system could be downloaded, jailbroken, and re-uploaded through iPHUC, similar to the Symlinks and LibTiff exploits. The most popular method of TIFF jailbreak, AppSnapp, later updated their payload to automatically apply OktoPrep for easier 1.1.2 jailbreaking. This was in response to complaints about how long it took to jailbreak 1.1.3, which originally had to be jailbroken through a long process involving jailbreaking 1.1.1, moving on to 1.1.2, and finally upgrading to 1.1.3.

This exploit was closed in 1.1.3 when /private/etc/fstab was changed so that /private/var was mounted with the 'nodev' flag in addition to the others.