Jailbreaking the iPhone 3G S / 4 on 4.2.1 firmware with greenpois0n (no unlock)
Updated: February 7, 2011
Who is this guide for?
- iPhone 3G S (new or old bootrom) and iPhone 4 owners.
- Official SIM card, or unofficial SIM card.
- I used iTunes version 10.1.2.
- I used OS X 10.6.6.
Thanks go out to the Chronic Dev Team for providing this amazing, and FREE program for
customizing the iPhone. You can visit their website here,
their blog here,
and their Twitter here.
Some notes if you are already jailbroken using a previous method.
- If you used redsn0w to achieve a tethered jailbreak on 4.2.1 then just follow these
instructions. If you have any problems, then restore the phone to 4.2.1 and try again.
Keeping in mind that restoring updates modem firmware, so do so properly.
- If you used redsn0w and performed the Jailbreak Monte method to untether, then you
MUST restore to 4.2.1 first before using this tutorial. Keeping in mind that restoring updates modem
firmware, so do so properly.
Here's my iPhone 4 already on 4.2.1 and 3.10.01 after a factory fresh restore. You can do this
with a freshly restored iPhone 3G S as well. If you do not have an official SIM card to activate
with, you won't be able to get to these screens after a fresh restore. Don't worry, I'll cover this
Double click the .zip to decompress
it. A folder will appear. Open the folder and drag the greenpois0n.app icon into your Applications
folder on your Mac.
Download 4.2.1 firmware from Apple here:
Launch greenpois0n. Make sure your iPhone is plugged into your Mac (I left mine powered on). Click
the Jailbreak button.
You'll have three seconds to press and hold the Power (sleep/wake) button.
While holding the Power button press and hold the Home button.
Release the Sleep button, but keep holding the Home button.
A blue status bar will zip by a few times.
A couple lines of text will appear at the top of the screen. Then code will scroll and fill up the
Click the Complete button and the program will close.
The code will pause for about one minute and then continue scrolling slower. A skull logo will
appear on the iPhone and change to an Apple. You may also see a spinning wheel under the skull.
Note: this new animation logo makes the phone boot slower. If you want to remove the skull logo
then install OpenSSH onto the iPhone and then go to the /usr/bin directory and delete (or rename)
the file named animate.
If you do not have an official SIM to activate with (people in the U.S.A. can use the following
SIMs, regardless if they are active or not: AT&T, AT&T GoPhone, Cingular, H2O, Net10, and O2 (the
U.S.A. company, not the U.K. one) then you'll most likely see this screen after the restore in
iTunes is complete. Continue with Step 3 if you are at this screen.
If you do have an official SIM and are already activated, then skip ahead to Step 4.
This step is only for those who do not have an official SIM card to activate with. Download redsn0w
0.9.6 rc8 from the iPhone Dev Team
Double click it to decompress the file. A folder will appear.
Drag the redsn0w.app icon into your Applications folder on your Mac.
Launch redsn0w and click the Browse button.
Navigate to your 4.2.1 firmware, select it and click Open.
You'll see the message IPSW successfully identified. Click Next.
A pop up window will appear.
Check only the install Cydia box. Click Next.
Turn off your iPhone. Click Next.
Instructions for entering DFU mode will appear. They start right away and go very quickly so try to
keep up! First hold down the Power (sleep/wake) button for three seconds.
Keep holding on to the Power button, and press and hold the Home button for 10 seconds.
Continue holding the Home button, and release the Power button.
Redsn0w will display various messages.
You'll see a graphic that says jailbreak data is being downloaded on the iPhone.
Done will appear in the program. You can ignore everything else on this screen, it doesn't apply.
Scrolling code will appear on the iPhone.
You will see a few different messages (Installing base utilities, Replacing kernel, Flashing NOR,
Flashing Baseband, Installing bundles, Activating, Syncing file systems, Moving Applications,
Rebooting) on your iPhone during the next couple minutes. The iPhone will reboot once this has
When the process has finished the iPhone will be hacktivated. This may cause problems like
accelerated battery drain (because of invalid Push notification certificates), et cetera. Cydia
will already be installed. If you want you can delete the Loader program. Read in Step 4 on how
to do this.
Ensure you have an Internet connection then press the Loader icon. Press Cydia.
Press Install Cydia. It could take some time to download. You could also use redsn0w to install
Cydia. But do not select any other options in redsn0w.
When it finishes installing press the Home button then launch the Loader again. Press the Options
button. Press the Remove Loader.app button. Press the Home button and the iPhone will respring.
If you do not see Cydia, then reboot your iPhone. Launch Cydia. You'll see the message Initializing
Filesystem. When it has finished Cydia will close. Enjoy being jailbroken!