How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

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These are instructions on how to jailbreak your iPhone 4 on the 4.2.1 firmware using RedSn0w for Mac. You will only be able to perform a tethered jailbreak at this time. This means you will need Redsn0w's assistance to boot into your jailbroken device.

If you want to jailbreak a lower firmware version you can find the appropriate tutorial here.

Make sure not to update to iOS 4.2.1 if you need an unlock as one is not yet available!

Step One
Create a folder on your desktop called Pwnage

Download RedSn0w from here and place it in the Pwnage folder. Likewise, download the latest 4.2.1 firmware from below and place it in the same folder.

4.2.1 (4): iPhone3,1_4.2.1_8C148_Restore.ipsw

Extract the redsn0w app from the RedSn0w zip file by double clicking it.
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Step Two
Connect your iPhone to the computer and launch iTunes.
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Select your iPhone from the list of devices on the left. Now hold down Option and click the Restore button. Restore is preferred as it won't create any wasted space on your iPhone.
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Navigate to the Pwnage folder on your desktop and select the 4.2.1 firmware ipsw. Click the Choose button to continue.
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Step Three
Once iTunes has finished updating your iPhone to the desired firmware open the Pwnage folder on your desktop and launch the redsn0w application from the redsn0w folder we extracted earlier.
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Step Four
Once RedSn0w opens click the Browse button
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Step Five
Select the 4.2.1 firmware ipsw we placed in the Pwnage folder on our desktop then click Open.
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Step Six
Once the firmware has been verified click the Next button to continue.
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Step Seven
RedSn0w will now prepare the jailbreak data
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Step Eight
From this window you can select the jailbreak options you would like.

Make sure Cydia is selected and click the Next button to continue
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Step Nine
Please plug your iPhone into the computer and make sure its OFF then click the Next button
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Step Ten
RedSn0w will now guide you through the steps to get into DFU mode. You can find more help with DFU mode here
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Hold down both the Home button and the Power button for 10 seconds.
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Release the Power button and continue holding the Home button until RedSn0w detects the device.
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Step Eleven
Your iPhone will now reboot
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Step Twelve
RedSn0w will then begin uploading the new RAM Disk and Kernel.
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

Step Thirteen
Once this is complete you will be notified that RedSn0w is done. Click the Finish button. When your iPhone finishes rebooting (5 minutes or so) it will be jailbroken with Cydia on the SpringBoard.
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]


IMPORTANT:
To use Redsn0w to help you boot back into your jailbroken device simply select Just boot tethered right now from the options window and click Next.
How to Jailbreak Your iPhone 4 Using RedSn0w (Mac) [4.2.1]

*As usual a big thanks to the iPhone Dev-Team for their hard work and contribution to the iPhone community.
modemode55 - January 8, 2013 at 8:57pm
gooooooood thx
Brock - February 14, 2011 at 1:43pm
I have an iphone 4 version 4.2.1(8C148) with firmware 03.10.01, all I want to do is Jailbreak it and not unlock it because I have AT&T. on other comments I\'ve seen that this updates the baseband... will this void my factory warranty and applecare? thanks!!
范駿 - March 24, 2013 at 10:16pm
我基帶降不了
Arif - January 24, 2011 at 5:55pm
Hi, i just jailbroken my iphone 4. the cydia is installed, but its white app. not brown as it should be. when i click on it the cydia does not open nor safari. can anyone help me. i have macbook, mac os x leopard.
tony - January 23, 2011 at 12:44am
I did the steps to jaibreak and cydia works fine when tethered, but Safari does not work??? opens and closes right away.
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