HACKSTOR: [How-To] Untethered Jailbreak for iOS 4.2.1 using GreenPoison RC6.1 *UPDATE*

Update 2 : Version RC6.1 released !

v6.1

Chronic Dev Team has updated GreenPois0n to RC6.1 which incorporates fix by Comex for iBooks DRM error after jailbreaking iPhone, iPad or iPod touch on iOS 4.2.1 it with GreenPois0n RC5/6.

Update : Now Windows version is out !!

Chronic Dev Team has finally released the much awaited GreenPois0n RC5 which brings full untethered iOS 4.2.1 jailbreak for all iOS devices. Unlike Redsn0w 0.9.7, GreenPois0n RC5 doesn’t require you to have SHSH blobs of 4.2b3 saved on Cydia. You can jailbreak any iOS device out of the box on iOS 4.2.1 using this latest version of GreenPois0n.

If you want to jailbreak a Verizon iPhone on iOS 4.2.6, read this.

Greenpois0n RC6 is compatible with :

iPhone

iPhone 3G
iPhone 3GS
iPhone 4

iPod Touch

iPod Touch 2G
iPod Touch 3G
iPod Touch 4G

iPad

iPad Wi-Fi
iPad Wi-Fi + 3G

NOTE: If your iPhone 4 rely on an unlock, do not update to iOS 4.2.1 yet as doing so will upgrade your baseband, making it impossible for now to unlock.

Step 1: Download GreenPois0n from the link given below.

Step 2: Connect your iPhone via USB to your computer and click on “Jailbreak” as seen in the screenshot below.

Step 3: Now follow the following onscreen instructions to enter 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.

Step 4: GreenPois0n will now start “Jailbreaking” your iOS device untethered on 4.2.1.

Step 5: Your iPhone, iPad or iPod touch should now be successfully jailbroken on iOS 4.2.1. Now start “Loader” found on the homescreen and install Cydia.

This is it! You are done !