Untethered jailbreak

Summary

An untethered jailbreak is a jailbreak where your device does not require you to reboot with a connection to an external device capable of executing commands on the device.

Device

All iPhone, iPod touch, and iPad models including the iPhone 4 have an untethered jailbreak at the latest firmware currently available.

Devices with a newer bootrom, which include some iPhone 3GS units, "MC" model iPod touch 2G units, iPod touch 3G units, and iPhone 4 units can't have a untethered jailbreak by PwnageTool, as they would need the signature checks patched since they don't have the 24kPwn exploit anymore.

However, it is possible to perform a untethered jailbreak on any device with any firmware version between 3.1.2 and 4.0.1 using Jailbreakme (This include any iPad models, running 3.2 or 3.2.1). This new revision, codenamed "Star", stores some code inside the device's VRAM in order to perform the untethered part of the jailbreak. It can be seen as some colored pixels right before the SpringBoard is loaded.

Operating System

Jailbreakme runs on the device itself, so the untethered jailbreak for iOS 3.1.2 to 4.0.1 is completely independent from the operating system since there's no need to connect the device to any computer in order to jailbreak.

PwnageTool can only be used on MacOS X.