How to Jailbreak iPhone 3G Firmware 4.2.1

iOS jailbreaking is the process of removing software restrictions imposed by iOS, Apple’s operating system, on devices running it through the use of software exploits; devices include the iPhone, iPod touch, iPad, and second-generation Apple TV.

In this guide I’m gonna show you How to Jailbreak Iphone 3G running iOS 4.2.1. Sol let’s Begin.


  • Download RedsnOw [Mac Version, Windows Version]
    On Mac:

    1. Download the Mac version of Redsn0w
    2. Open it and navigate to your Downloads folder, and find the folder called Redsn0w.
    3. Open the Redsn0w folder and launch the app.

    On Windows:

    1. Download the Windows version of Redsn0w
    2. Click open in the dialog box
    3. Double click the Redsn0w folder
    4. Double click on the Redsn0w application
    5. Click run.
  • Download iOS 4.2.1 Firmware.


It’s time to jailbreak.

  1. Go to the Redsn0w window that you should already have open, and we can get started.
  2. Click the browse button in the Redsn0w window, and select the firmware file you just downloaded.
  3. Once you’ve selected your firmware, click next.
  4. In the next screen there will be several checkboxes, but the crucial one to check is the “Install Cydia” checkbox.
  5. Click next. Now the below steps are very crucial part of jail-breaking, so be attentive.
  6. Turn off your device by holding the sleep button for 5 seconds and sliding to power off.
  7. With the device turned off hold just the sleep button for 3 seconds.
  8. After three seconds are up, continue holding the sleep button and then start holding the home button.
  9. Hold the sleep and home buttons for 10 seconds. When 10 seconds pass, release the sleep button and continue holding the home button for 8 seconds.
  10. After 8 seconds you can release the home button, and watch Redsn0w do it’s thing.
  11. After about 5 minutes your device will reboot and you’ll see the Apple logo. If you can see the Cydia icon on your home screen, you’re jailbroken! Now you can start loading your device with tons of cool apps off the Cydia app store.

That’t it. You have successfully jailbreak iphone 3G running iOS 4.2.1.

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