Greenpois0n can jailbreak iPhone 4, iPhone 3GS running iOS 4.2.1 and it is an utethered jailbreak. Chronic Dev Team’s Greenpois0n jailbreak tool brings full untethered iOS 4.2.1 jailbreak for iPhone 4, iPhone 3GS, iPad and iPod Touch as well. If your device is running iOS 4.2.1 firmware, you can jailbreak it using Greenpois0n RC6.1. Unlike RedSn0w, Greenpois0n untethered jailbreak does NOT require SHSH blobs for iOS 4.2b3.
Clean iOS 4.2.1 restore is recommended (UltraSn0w unlocker must NOT do this).
The following instructions will help you jailbreak iOS 4.2.1 on iPhone 4, 3GS using GreenPois0n. It is an untethered jailbreak.
iPod Touch and iPad users should navigate to their respective guides here:
In this guide, you’ll learn how to jailbreak iPhone 4, 3GS running iOS 4.2.1 using Greenpois0n jailbreak…
How to Jailbreak iPhone 4, 3GS iOS 4.2.1 with GreenPois0n
Your iPhone 4 or iPhone 3GS MUST be running iOS 4.2.1 firmware.
- Download Greenpois0n [Windows | Mac OS X]
Download iOS 4.2.1 (in case you need to restore)
- Backup your personal data using iTunes;
- Extract the Greenpois0n .zip file and run Greenpois0n;
- Click on the Jailbreak button;
- You’ll be instructed to put your iPhone4/iPhone 3G into DFU mode:
- Press and hold the sleep button for 2 seconds;
- Continue holding sleep; press and hold home for 10 seconds;
- Release sleep button; continue holding home for 15 seconds.
- Greenpois0n will begin jailbreak iPhone4/3GS on iOS 4.2.1 as soon as it enters DFU mode;
- Once the jailbreak process is complete, a Complete button will appear on greenpois0n and there’ll be a flood of commands on your iPhone screen;
- Just wait for your device to reboot automatically. Your iPhone 4/3GS has been jailbroken. One last thing to do here is to open Loader app from your iPhone home screen and install Cydia.
That’s it! You’ve sccessfully jailbroken iPhone 4, 3Gs iOS 4.2.1 with Greenpois0n jailbreak.