How to jailbreak iPhone, iPad, iTouch iOS 4.2.1 with redsn0w 0.9.6b4: guide and video tutorial

November 24, 2010 by James

Now that the iOS 4.2.1 is available to download for the iPhone, iPad and iPod Touch, while the iPhone Dev Team have released redsn0w 0.9.6b4 jailbreak tool for it, those who are new to jailbreaking may be wondering how the process is done.

Below you will find a full how to guide that will explain step by step how to jalbreak iOS 4.2.1 on your idevice using redsn0w 0.9.6b4.

PLEASE KEEP IN MIND THAT ACCORDING TO THE IPHONE-DEV TEAM IF YOU WANT TO BE ABLE TO UNLOCK YOUR IPHONE YOU SHOULD STAY AWAY FROM IOS 4.2.1. SO IF YOU INTEND ON UNLOCKING YOUR IPHONE IN THE FUTURE DO NOT UPGRADE TO IOS 4.2.1 AND DISREGARD THIS ENTIRE TUTORIAL.

Before we begin you might want to take SHSH blobs of your currently installed iOS version using TinyUmbrella before you do anything. Just in case.

IOS 4.2.1 JAILBREAK GUIDE

* PLEASE UPGRADE TO iTunes 10.1 FOR BEST RESULTS
* WINDOWS 7 USERS SHOULD RUN redsn0w IN “XP COMPATIBILITY” MODE

#1 – Download redsn0w 0.9.6b4.
#2 - Download the corresponding iOS 4.2.1 firmware for your exact iPhone model to your computer (right click on it and select to save).
#3 – After connecting your iPhone to your computer, open iTunes, hold down your keyboard’s SHIFT button and click on “upgrade”.
#4 – Select the iPSW iOS firmware file that you’ve just downloaded in step #2 and let iTunes upgrade your iOS to iOS 4.2.1.
#5 – Start redsn0w 0.9.6b4.
#6 – Inside redsn0w, select the same IPSW file that you’ve just downloaded and used in step #4.
#7 – Select whatever options you want (hint: you’ll probably want to select to install Cydia) and click on “next”.
#8 – Make sure your iPhone is connected to your computer and is turned off. Then click on “next” again.
#9 – Following the instructions on your screen, enter your iPhone into DFU mode (by holding down the power and home button for about 15 seconds and then releasing the power button while still holding down the home button)
#10 – Now the jailbreak process will begin and it will take a few minutes for it to complete.

If everything worked okay, your idevice was successfully jailbreaked.

And directly below you can see a video tutorial of the process.

IMPORTANT NOTE:

Keep in mind that with the newer iPhone 3GS and iPhone 4 devices, as well as with the iPad and iTouch you will only have tethered jailbreak. That means that if you want to use Cydia or access non-AppStore apps you’ll need to do a “tethered boot” first. That can be done by selecting the option “Just boot tethered right now” from redsn0w. You’ll need to do it every time you reboot your device.

Tags: Cydia, firmware, guide, how to, iOS, iOS 4.2.1, iPad, iPhone, iPhone 3G, iPhone 3GS, iPhone 4, iPod Touch, jailbreak, redsn0w, redsn0w 0.9.6b4, tutorial

Article by James

My name is James Farlow, I'm 23 years of age, attending university in computers engineering and apart of that I enjoy blogging here and now for a few sites. The phone that I currently use is a custom modded white iPhone 4 but am really looking forward to iPhone 5.

Anonymous

wow, nice read, so full guide, many fans must be waiting lone time!
At least I have wait the iOS 4.2 too long, the multitasking and folders are what Im looking forward lonr time!!
Though I have jailborken my iPHone 4 followed this guide “Jailbreak iPhone 4 iOS 4.1 with GreenPois0n on Mac” loacated in iFunia iPhone column, but now I should updated to iOS 4.2!!!
Lyakine

Thanks for the Tuto. everything went fine during the jealbreak. However, after finishing all the steps i’ve faced an issue as my iPhone 3G is not able to get access to the operator. the baseband is on 05.15.04 is any one have an idea how to fix this issue?
Anonymous

Jailbreak does not mean unlock.

Jailbreak allows ultrasn0w to work.

However iOS 4.2.1 is not supported by the current version of ultrasn0w. Hence you cannot unlock your iPhone atm.
http://www.arcx13.com ARC™

after it enters the DFU mode, the window on my laptop screen just show the progress to be completed halfway. (those green progress bars)

Ive checked mine it was on 4.2.1
what’s happening?
http://www.facebook.com/people/Tom-Cruize/100001659985378 Tom Cruize

Last Jailbreak avaiable on http://www.unlockiphone4-now.com
http://www.facebook.com/people/Tom-Cruize/100001659985378 Tom Cruize

Last Jailbreak avaiable on http://www.unlockiphone4-now.com
iPodUser

I tried following the instructions with my iTouch 2g MC model. I have downloaded the 4.2.1 firmware. When I run Redsn0w and select the firmware, I am asked whether my iPod is the MC model. It is, so so click “yes” and get a message saying “coming soon this version of redsn0w doesn’t support the iPod 2G MC model yet. Check back soon.”

Why is this? All the posts I read say that the MC model is supported with a tethered jailbreak.

Any ideas?
Krisztina

perfectly working for me, thank you soooo much!
JohnnyCash

after posting this, you should also add a guide of how to restore your device after getting fu**ed up. (experienced it 3 times)
Soul

I have Jailbroken my 3G on 4.2.1 now every thing is working f9 but itunes is nt detecting my phone?? can any1 help me
Soul

I have Jailbroken my 3G on 4.2.1 now every thing is working f9 but itunes is nt detecting my phone?? can any1 help me
Bahodirbek

im trying to jailbreak my iphone… but when it says uploading ramdisk on my laptop phone turns on and and laptop still says same thing and i waited 1 hrs but nothing happend. what should i do?
Pennymykitty61

Okay I can find the file when i go to browse. HELP!
Joshheartsasd

I did it on my iPod touch 2g it worked great even gave me multitasking and wallpaper, but when itried it on my iPod touch 4g it would go all the way through but in the end it wouldn’t fully load cydia. The appp was just blank with cydia underneath it. And it wouldn’t load
http://www.simunlockiphone.net sim unlock iphone

I unlocked my iPhone at http://www.simunlockiphone.net and it worked