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Download GreenPois0n RC5 for Untethered iOS 4.2.1 Jailbreak on Mac OS X [Video Tutorial]

Its here folks! Chronic-Dev Team has released its much awaited version of GreenPois0n tool i-e GreenPois0n RC5 which brings untethered iOS 4.2.1 jailbreak on all iOS 4.2.1 iDevices. Unlike betas of Redsn0w 0.9.7, there are no Bluetooth and Skype issues after the jailbreak plus you don't need iOS 4.2b3 SHSH blobs to jailbreak your iOS 4.2.1 iDevice.

GreenPois0n Logo

iDevices Supported by GreenPois0n RC5:

  • iPod Touch 2G (MC & MB)
  • iPod Touch 3G
  • iPod Touch 4G
  • iPad 1G
  • iPhone 3Gs (Old & New Bootrom)
  • iPhone 4
  • iPhone 4 Verizon (Not Tested)
  • AppleTV 2

NOTE: If you rely on an unlocked iPhone, do not use this jailbreak for now as this will upgrade the baseband of your iPhone, making it impossible to unlock via current version of Ultrasn0w tool. If you don't rely on an unlocked iPhone or if you have previously used a Redsn0w 0.9.7 for a tethered jailbreak, then it is recommended to restore stock iOS 4.2.1 IPSW using iTunes on your iDevice before you may proceed to the jailbreak-steps below.

MuscleNerd iOS 4.2.1 GP Tweet

UPDATE: According to MuscleNerd, who happens to be a member of iPhone Dev-Team, you can use GreenPois0n without restoring stock iOS 4.2.1 IPSW if you already have jailbroken your iDevice using Redsn0w 0.9.7. (via MuscleNerd)

How to Jailbreak (Untethered) iOS 4.2.1 Using GreenPois0n RC5?

*Find download links at the bottom of the post

  1. *Download GreenPois0n RC5 tool for Mac OS X.
  2. *Download stock iOS 4.2.1 IPSW for your iDevice.
  3. *Download and install iTunes 10.1.2 for Mac OS X.
  4. Connect your iDevice to your Mac via USB cable.
  5. Start iTunes and backup all of your device data including Apps, Photos, Music, Contacts, Messages etc
  6. Restore stock iOS 4.2.1 IPSW you downloaded in step 2 (Only if you don't rely on an unlocked iPhone).
  7. Start GreenPois0n RC5 and click on the 'Jailbreak' button at the bottom.
  8. GreenPois0n iOS 4.2.1 Mac OS X Jailbreak

  9. Now use the following instructions to put your iPhone, iPod Touch or iPad in DFU mode:
    • Press and hold sleep button for 3 seconds.
    • While holding the sleep button, press and hold the home button for 10 seconds.
    • After 10 seconds, release the sleep button but keep holding the home button for 15 seconds.

    GreenPois0n iOS 4.2.1 Mac OS X Jailbreak

  10. Once GreenPois0n will detect your iDevice in DFU mode, it will jailbreak it in a matter of seconds.
  11. GreenPois0n iOS 4.2.1 Mac OS X Jailbreak

  12. Once the jailbreak is done, click on the 'Complete' button to close the GreenPois0n tool.
  13. GreenPois0n iOS 4.2.1 Mac OS X Jailbreak

  14. Once jailbreak has been done, you will see the 'Loader' app on your iDevice home screen. Use the 'Loader' app to install Cydia and then remove it from your Springboard.
  15. iOS 4.2.1 iP4 Cydia Installed

Video Tutorial:

Update#1: Chronic-Dev Team has released GreenPois0n RC5_b2 which fixes several bugs including GP initialization error. [Download | Mirror]
Update#2: GreenPois0n RC5_b3 has been released. [Download | Mirror]
Update#3: Chronic-Dev Team has released GreenPois0n RC5 for Windows. Click here for more information.
Update#4: PwnageTool bundles for untethered iOS 4.2.1 jailbreak on iPhone 4 and iPhone 3GS released. Click here for the jailbreak tutorial.
Update#5: Chronic-Dev Team has released GreenPois0n RC5 B4 to jailbreak iOS 4.2.6 on Verizon iPhone 4.
Update#6: Unlock for iPhone 4 02.10.04, 03.10.01 & 04.10.01 Baseband is Almost Ready!
Update#7: Download official PwnageTool 4.2 for untethered iOS 4.2.1 jailbreak on Mac
Update#8: Download Sn0wbreeze 2.2 for untethered iOS 4.2.1 jailbreak on Windows

Download Links:

Download GreenPois0n RC5 | Mirror
Download iOS 4.2.1 for iPhone, iPod Touch & iPad
Download iTunes 10.1.2 for Windows and Mac OS X

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Leave a message...

    ruben10 years, 6 months ago

    hi there,
    i have an iphone 3GS and i have already installed version 4.3 but now i want to jailbreak it so i have to ‘downgrade’ it to version 4.2.1 but i dont know how to do that. Can anyone please help me?

      Wolverine10 years, 6 months ago

      Follow this downgrade guide

        Ruben10 years, 6 months ago

        Oh, wait, i forgot to say that i havent jailbreaked it yet so i have not such thing as SHSH or whatever..

          Wolverine10 years, 6 months ago

          Without SHSH blobs, downgrading is impossible. Don’t want to keep in dark by giving false hopes!

            ruben10 years, 6 months ago

            ok so be it

    david10 years, 7 months ago

    I have iPhone 3GS. I had a 1015 error from itunes which put me in a recovery mode and wouldnt come out of it no matter what i tried on the internet i looked every where nothing worked then i came across greenpois0n thanx to you all for fixing my phone !!!!