How to Jailbreak Your iPhone 3GS, iPhone 4 Using Greenpois0n (Windows)

Remember: Do not update to iOS 4.1 if you need the unlock. Ultrasn0w does not support that baseband yet. The only exception is the iPhone 4. You can update to iOS 4.1 without upgrading your baseband by following this tutorial.

Step One
Open your web browser of choice and navigate to http://www.greenpois0n.com. Click the Windows link at the bottom of the screen.

Step Two
When prompted save the download to your desktop

Step Three
Double click the downloaded gp_win_rc2.zip file then drag the greenpois0n.exe file to the desktop. Double click greenpois0n.exe from the desktop to launch the application

Step Four
Power off your iPhone then click the large Prepare to Jailbreak (DFU) button

Step Five
You will now be instructed on how to place your iPhone into DFU mode.

You will be asked to 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 Six
Once your iPhone is successfully in DFU mode you may click the Jailbreak button.

Step Seven
Greenpois0n will now jailbreak your device

Step Eight
Click the Quit button once the software application has completed.

Step Nine
After the iPhone restarts you’ll notice a new Loader application on your Springboard. Press to launch it.

Step Ten
Press to select Cydia then press the large Install Cydia button that appears.

Step Eleven
Once Cydia has installed successfully you will be asked if you want to remove Loader from your device. Press the Remove button then press the Home button. Your device will now automatically reboot.

Step Twelve
When your iPhone has restarted you can run Cydia. Let it do all the necessary updates then follow our Unlock tutorial if possible for your device.

***A big thanks goes to the Chronic Dev Team who made this jailbreak possible.