How to Jailbreak iPhone 4.2.1 with PwnageTool 4.2 (Mac)


If you want to jailbreak your iPhone on iOS 4.2.1, and you don’t require an unlock, use Greenpois0n. However, if you want to remain at an unlockable baseband, you’ll want to use PwnageTool 4.2 (Mac) or sn0wbreeze 2.2 (Windows).

Here’s a brief tutorial on how to jailbreak your iPhone on iOS 4.2.1 with PwnageTool. It’s straightforward and similar to Greenpois0n, except you will restore iPhone with a custom firmware that PwnageTool 4.2 will create for you.

By restoring with a custom firmware, and not updating to 4.2.1 in iTunes, your iPhone baseband will remain the same. This only applies to people who need an unlocked iPhone, and want to continue with an unlockable baseband.

As always, jailbreak at your own risk. We are not responsible for anything that goes wrong.

Brief Step by Step Guide on How to Jailbreak your iPhone on iOS 4.2.1 with PwnageTool 4.2 (Mac Only)

1. Download the latest version of iTunes. Sync your iPhone before you begin.

2. Download iOS 4.2.1 firmware for your iPhone here, and PwnageTool 4.2 here. Save both to your desktop.

3. Launch PwnageTool, and select Expert Mode, then select your device.

4. Browse for iOS 4.2.1 firmware, click Open. Next, select ‘General’. If your iPhone is on an official carrier, untick ‘Activate the phone’. If you want to use your iPhone on an unofficial carrier, tick this box.

5. Click Build, then PwnageTool will start creating the custom firmware to jailbreak your iPhone. You will be asked for your system password for PwnageTool to proceed. Choose your desktop to save the Custom firmware:

6. Now, you’ll have to enter DFU mode (if this messes up, try again; takes some practice) by:

a) Hold the Power/Home buttons for 10 seconds
b) Release the Power button, but keep holding Home for 10 seconds
c) If successful, you’ll be in DFU mode.

7. Launch iTunes, select your iPhone. Press ‘Alt/Option’ on your keyboard, then click on ‘Restore.’ An iTunes prompt appears–select the CUSTOM firmware created by PwnageTool.

8. As your iPhone restores (10 minutes or so), it will be jailbroken on iOS 4.2.1, with your existing baseband. The iPhone should reboot, and the jailbreak will be done. Cydia will now be on your homescreen.

Let me know how the above works for you!


  • yeahman

    it would be a good idea to note that this is for people who haven’t already upgraded to 4.2.1, I got excited and was let down as soon as I realized that’s it’s another “retain your baseband” rather than “downgrade your baseband” article

  • TomnJerry427

    Is there any way to downgrade baseband for people already on 4.2.1? Or unlock for people already on 4.2.1 factory through iTunes. Please let me know, thank you!

  • TonygBaker

    Hi Gary,
    If my phone is already activated with Rogers, but I’m currently on the vodafone network while in the uk do I still need to tick activate phone or can I untick that box? What does official and unofficial carrier refer to anyways? Thanks again. These guides are priceless.

  • Are you roaming, or is your iPhone unlocked with a Vodafone SIM?

    If your iPhone 4 is factory unlocked from Apple–untick activate

    If you unlocked with ultrasn0w–tick activate

    Official carrier: iPhone from Rogers, activating on Rogers
    Unofficial: iPhone from Rogers, activating using another carrier SIM

  • TonygBaker

    Thank you. My phone is unlocked with ultrasn0w with a vodafone sim. I was unsure since with the last update to 4.1 I unticked activate. Thanks for clarifying things for me.

  • TonygBaker

    Everything worked great! Thank you for the excellent guide and for your advice. They were a great help.

  • Awesome! You’re welcome. 🙂

  • Smpwnage69

    If you are already running 4.2.1 with the baseband 03.10.01, is there away to either unlock the phone with this baseband or downgrade your baseband to an unlockable one? I have already jailbroken the phone with greenpoison rc5, thanks for your help.

  • Ralph

    can i use this with a telus i-phone in Canada?

  • Ralph

    I am on a Telus network in Canada

    My version is 4.2.1 (8C148) and my modem firmware is 03.10.01.

    Can you please tell me if I can use this program, and if so, can you please guide me through the steps, because I have never done anything like this before?

    Thank you very much

  • Ex
  • Yes

  • If I wanted to unlock a telus phone to use on any network. Could I follow these steps?
    Great tutorial!

  • Lui-nan

    Thanks to your guide I have jailbroke iPhone3 on 4.2.1, baseband 5.15.04 and able to install Cydia. But now I am stuck.  All the applications did not transfer (just initial Apple ones).  Connecting to iTune it asks to either set it up as a new iPhone or restore…. Wouldn’t both options “unjailbroke” the iphone?

    Thanks.  I am stuck with Rogers but need it in Europe with Vodaphone.

  • Creditspread

    Didn’t work, iTunes does a validation of the IPSW that you load and says there is an error and will not let you proceed with the loading of the IPSW to your phone.

  • libby

    phone has now been rendered unresponsive & itunes does not recognize it. this happened when trying to get into DFU mode. any ideas?

  • libby

    correction to previous post. iphone re-activated on its own and DFU mode successful. now i have to unlock it. thanks for the clear instructions.