How-to Jailbreak iOS 4.2.1 Untethered using GreenPois0n RC5

On February 4, 2011

greenpois0n logo

How-to Jailbreak iOS 4.2.1 by using GreenPois0n RC5

What is greenpois0n? It’s another jailbreak tool created by Chronic Dev-Team.

  • Greenpois0n can be used to jailbreak iOS 4.2.1 untethered.
  • Greenpois0n doesn’t support hacktivation.
  • Greenpois0n RC5 supports iPhone 4, 3GS (any bootrom), iPod Touch 4G, 3G, 2G (any bootrom) and iPad.
  • If you previously jailbreak using redsn0w, simply run the greenpois0n, no need to restore fresh firmware.
  • If you previously jailbreak redsn0w monte, you need to restore iOS 4.2.1 first (fresh firmware).

1. Download greenpois0n RC5 (RC5_2 is updated version)

2. Download iOS 4.2.1 IPSW File

3. Extract ( is older version still buggy, is updated version).

4. Connect your iPhone to computer then turn it off while it still connected.

5. Run greenpois0n and click Jailbreak.

6. Get ready to start. greenpois0n will help you how-to enter DFU mode in three steps

7. Once iPhone enter DFU mode, greenpois0n will start jailbreak the iPhone automatically.

8. While greenpois0n jailbreaking the iPhone, do not either close greenpois0n nor disconnect the iPhone from computer. Your iPhone screen will be flooded by texts while greenpois0n is in action.

9. Once jailbreak complete, you will see “Complete!” button on greenpois0n.

Jailbreak is done.