How To Jailbreak iOS 4.2.1 With GreenPois0n 1.0 RC5

The Chronic Dev Team has released Greenpois0n 1.0 RC5, an update to their jailbreak utility which, in its current state, can effectively provide an untethered jailbreak to iOS 4.2.1 devices. The jailbreak tool also does not require developer saved SHSH blobs of 4.2b3.

Those who enjoy the benefits of rocking a jailbroken iOS device should be aware that there are certain people in Cupertino, California that don’t condone the practice and even make a habit out of voiding warranties if they find out that folks jailbroke their unit.

Then again, a vocal group called the Electronic Frontier Foundation once said it was legal to jailbreak.

So it’s ultimately your decision, and your decision only. Also note that Greenpois0n 1.0 RC5 will not provide a carrier unlock and will, in fact, break it.

This guide is for Mac OS X users only. The same steps should apply for Windows and Linux users when Greenpois0n 1.0 RC5 becomes available for those platforms as well.

Without further ado, jailbreaking iOS 4.2.1 with Greenpois0n 1.0 RC5 is done as follows:

1. Backup your iPhone / iPod touch / iPad using iTunes, just in case anything goes wrong and you need to restore your firmware to a stock IPSW.
2. Download GreenPois0n 1.0 RC5 from Chronic Dev.
3. Connect iOS device to your computer.
4. Launch GreenPois0n and click on “Jailbreak”.
5. Follow the onscreen instructions and proceed to timely press the buttons on your iOS device as instructed:
   - Press and hold sleep button for 2 seconds;
   - Continue holding sleep, press and hold home button for 10 seconds;
   - Release sleep button, continue holding home button.
6. With your iOS device now in DFU mode (or so it should be at this point), click on the “jailbreak” button. Now Greenpois0n will inject its ‘poison’ in your iOS device, jailbreaking it.
7. Allow your iDevice to reboot. At this point, you are already jailbroken.
8. Once your device is up and running again, you can install Cydia by tapping on the “Loader” icon which should be present on one of your home screens.

That’s it!

• This article has a purely informational purpose and doesn't, in any way, suggest that you should hack your Apple device.
•  Using hacks may render your device unusable, or may reduce the quality of your experience employing the respective device.
•  If you choose to download and install jailbreak tools, you will do so at your own risk. Unlocking / jailbreaking your iPhone / iPod touch / iPad / Apple TV may violate your warranty or the EULA with Apple and / or your cellular-service provider.