How To Jailbreak the iPhone 4 on 4.3.1 “Tethered”

Looking for an iPhone 4 jailbreak? You’re in luck. Follow this detailed how-to guide on how to jailbreak the iPhone 4 using a tethered jailbreak. As a reminder, if you get stuck or have questions, we’ve set up a support thread in our Jailbreak forums to help you out. Let’s get started.

iPhone 4 Jailbreak

First off, you will need iOS 4.3.1 installed on the iPhone 4. Also, you will need access to the 4.3.1 .ipsw file, which you can download directly from Apple.

Make sure that iTunes is fully updated to 10.2.1. This particular jailbreak requires Pwnage Tool, you can download version 4.2. You will also need to download the appropriate Pwnage Tool bundle and the Universal Ramdisk Fixer. When you download Pwnage Tool, right click on it, click “Show Package Contents“. Then navigate to: Contents/Resources/FirmwareBundes and copy and paste the bundle you downloaded earlier into this folder.

Pwnage Tool
Make sure that you drag the Pwnage Tool 4.2 application into the Applications directory, this you have to do. Now turn back to the Ramdisk fixer which you downloaded earlier and launch it. You need to run this because it patches 4.3.1 firmware, so it works with Pwnage Tool. Follow the onscreen prompts and install the Universal Ramdisk fixer. Now you will need to “cook” your 4.3.1 custom firmware. Launch Pwnage Tool and select expert mode and select iPhone 4. You will be prompted to browse for the 4.3.1 firmware (remember, the firmware you downloaded earlier).

Expert Mode

When you’ve found the firmware, click next and press “Build”.

Build Pwnage

Once you’ve successfully built your custom 4.3.1 .ipsw, Pwnage Tool will prompt you to enter DFU mode. Carry out the onscreen prompts and enter DFU mode. You will see a pop-up stating you’ve successfully entered DFU mode. Launch iTunes and click on your iPhone 4 in the left-hand sidebar. Now hold down the left “Option” (Alt) button and click on Restore. You will see yet another pop-up appear, this is where you will search for your custom 4.3.1 .ipsw file.

Select custom firmware

When you’ve found the custom 4.3.1 firmware, click on the “Choose” button. iTunes will now restore the device to a tethered jailbroken 4.3.1 iOS.

Next is the tricky part… please stay with me. As this is a tethered jailbreak, you need to boot it every time it runs out of battery or reboots etc. You will need to download the Tetheredboot Utility. Now, make a copy of your custom 4.3.1 firmware which you created earlier. I find it easier to create a new folder and copy the original and paste it into that. Now rename the .ipsw to .zip. A warning will pop-up, just click use .zip. Now extract the newly zipped firmware.

Extracted custom firmware

You need two files, one is on the screenshot above:  kernelcache.release.n90. Copy this into a new folder called Tetheredboot. The second file is located: /Firmware/dfu/ called:  iBSS.n90ap.RELEASE.dfu. Copy this into the folder you’ve just created. Now drag and drop the Tetheredboot utility into the folder as well.

Tethered Boot Folder

Now launch Terminal (Utilites > Terminal) and enter the following commands:
sudo -s (press enter)
enter your password” (press enter)

Now drag and drop the “tetheredboot” file into the Terminal screen and type -i after it.


Now drag and drop “iBSS.n90ap.RELEASE.dfu” file into the Terminal screen and type -k after it.


Now drag and drop “kernelcache.release.n90” file into the Terminal screen.


Now, the next step is to enter DFU mode again.Hold down the Power button for 3 seconds, then hold down both the Power and Home buttons for a further 10 seconds. When you get to 10 seconds release the Power button but continue holding down the Home button for a further 15 seconds.

The screen on the iPhone 4 should be blank. Now tap enter on the Terminal screen. You will see lines of code running and it should say “Exiting libpois0n“. The phone will now boot into a tethered mode. You will have to repeat the steps in Terminal a few times after you’v refreshed Cydia and installed a few packages. As I mentioned above, once you’ve done this a few times, it becomes easy. If you have questions, you can either leave a comment below or post a question in the support thread in our Jailbreak forums. Enjoy your tethered jailbroken iPhone 4 on iOS 4.3.1.


  1. Hawk says

    Well that certainly is a very detailed article on jailbreaking, but I have to ask, is this a Mac only jailbreak or is Windows available too??
    Great job on putting it together John!

  2. Eric says

    Lets hope the Dev team is close on an untethered jailbreak.
    Tethered jailbreaks are just too inconvenient. I dont need to be on 4.3/4.3.1 that bad.

    • iphonewarrior says

      The Dev-Team shouldn’t be far off now. I just hope it’s here soon, before Apple release another firmware update.

  3. roger says

    Hi there, I have been trying to jailbreak my new i phone4 but i keep getting This message: The “Iphone” could not be restored. An uknown error occured (1600).
    Any idea on how to go about it? Roger

    • iphonewarrior says

      The best thing for you to do now is update or restore to 4.3.1 and jailbreak using Redsn0w.

      Restore issue: Check your hosts file. This is usually the main culprit. Make sure you only have on IP address at the bottom of the file.

Leave a Reply