Untethered Jailbreak iPhone 4, 3GS on iOS 4.2.1 Using Greenpois0n RC5 on Mac [Guide]

Finally, Chronic Dev Team has released the much awaited GreenPois0n RC5 jailbreak tool for Mac which lets you jailbreak iOS 4.2.1 firmware on your iPhone 4, iPhone 3GS, iPod Touch 4G, iPod Touch 3G and iPad. Using GreenPois0n RC5 doesn’t require you to have SHSH blobs of 4.2b3 saved on Cydia.

Please note that you rely on unlock your device, don’t update to iOS 4.2.1 because there is no Ultrasn0w unlock available yet for iOS 4.2.1.

How to Untethered Jailbreak your iPhone 4, 3GS on iOS 4.2.1 with Greenpois0n RC5

1: Download Greenpois0n RC5 for Mac [Link] and unzip it. [Mirrors]

2: Open folder and double click Greenpois0n icon to launch it.

3: Connect iPhone 4, 3GS to the computer via USB, power it off and then click the Jailbreak button.

4: Now Follow the on-screen instruction to put the device in 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.

5: Once your iPhone 4, iPhone 3GS is in DFU mode, the jailbreak process will begin. Greenpois0n will jailbreak your iPhone on iOS 4.2.1.6: Click the Quit button once the software application has completed.

7: After the iPhone 4 restarts you’ll see a new Loader app on your Springboard, launch it and install the Cydia store.

Once the Cydia store has installed successfully on your iPhone 4, 3GS, you will be prompted if you want to remove Loader from your device. Press the Remove button then press the Home button. Your iPhone device will now reboot and you are done now.

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