How to Jailbreak iOS 4.2.1 – Now, Untethered!

In November, Apple shipped the 4.2.1 update for its mobile operating system iOS, and days later, the iPhone jailbreaking community had figured out how to hack it. Unfortunately for jailbreaking enthusiasts, the only hack available at the time was what’s called a “tethered jailbreak,” meaning that every time you reboot your device, you have to connect it (i.e.,”tether” it) to your computer.

But now, members of the hacking group known as the Chronic Dev Team have released a new jailbreaking tool called greenpois0n which delivers, at long last, the highly anticipated “untethered” jailbreak.

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Jailbreaking, for the uninitiated, is a term used to describe the process of hacking a mobile device to lift the restrictions put in place by the software maker or manufacturer, in this case, Apple. People jailbreak their iPhones (and iPod Touches and iPads, too) for a number of reasons – to install third-party applications Apple doesn’t approve, to use their phone as a Wi-Fi hotspot, to further customize the device’s user interface with themes and to generally tweak and customize things more to their liking.

The term does not, however, mean the same thing as “unlocking” – that refers to hacking a phone so it will run on another carrier’s network – for example, getting the AT&T iPhone to run on T-Mobile’s network. An unlocked phone must be jailbroken first, but a jailbroken phone does not need to be unlocked.

The Original 4.2.1 Jailbreak Tool: Redsn0w

The first group to jailbreak the newest iPhone operating system was the iPhone Dev Team, who released a tool called redsn0w. The software would work on both Mac and Windows machines, but as noted above, it required the phone to be tethered to a computer every time it rebooted.

We documented the procedures here in November with a warning that, frankly, this one should probably be skipped. It’s a huge pain to be tethered, we said, especially on an iPhone.

The New, Untethered Jailbreak: Greenpois0n

The new jailbreak – aka “greenpois0n” – now allows you to jailbreak your device without the tethering requirement afterwards. Unfortunately, it’s only for Mac users for now. From the website, it appears that both Windows and Linux versions are under development.

Greenpois0n does not support those who want to unlock their iPhones. The jailbreak does, however, support iPhone 3GS and iPhone 4, the iPad, iPod Touch 2G/3G/4G and even Apple TV (2nd generation).

How to Use Greenpois0n

To get started using this jailbreak, the following are the recommended procedures. A word of warning: some of the first to attempt this jailbreak are reporting issues and some are even saying that the jailbreak doesn’t work. For others, it’s taking a few times before the process works as designed. Others still say they don’t have any issues at all. In other words, proceed at your own risk!

If you’re feeling daring, then do the following:

1. Backup your device and restore it to iOS version 4.2.1, setting it up as a new device within iTunes.
2. Plug in your device to your computer and turn the device off.
3. Download and run greenpois0n on your computer. The onscreen instructions will guide you as to how to get into DFU mode on the device, which involves a series of button presses (press and hold sleep, press home, release sleep, continue holding home).

   

4. When your phone or other device enters into DFU mode, the jailbreaking process will begin.
5. When the process completes, you’ll have a new “Loader” icon on your homescreen. (Apple TV jailbreakers, of course, will not. They will need to use Terminal and SSH instead).

   

6. Tap the icon to install Cydia, the jailbreak app store.

Note that, at the time of writing, both the greenpois0n website and Cydia’s servers are experiencing high traffic loads and are intermittently up and down. Your best bet: wait a couple of days for the fervor to die down, then try again.

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