How to Jailbreak and Unlock Your iPhone 3GS Using RedSn0w (Windows) [4.2.1]

Posted November 28, 2010 at 11:44pm by iClarified | Please help us and submit a translation by clicking here | 378191 views
Portuguese (Brazil)  Spanish  

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.

Step Two
Connect your iPhone to the computer and launch iTunes.

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.

Navigate to the Pwnage folder on your desktop and select the 4.2.1 firmware ipsw. Click the Choose button to continue.

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.

Step Four
Once RedSn0w opens click the Browse button

Step Five
Select the 4.2.1 firmware ipsw we placed in the Pwnage folder on our desktop then click Open.

Step Six
Once the firmware has been verified click the Next button to continue.

Step Seven
RedSn0w will now prepare the jailbreak data

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

Step Nine
Please plug your iPhone into the computer and make sure its OFF then click the Next button

Step Ten
RedSn0w will now guide you through the steps to get into DFU mode. You can find more help with DFU mode here

Hold down both the Home button and the Power button for 10 seconds.

Release the Power button and continue holding the Home button until RedSn0w detects the device.

Step Eleven
Your iPhone will now reboot

Step Twelve
RedSn0w will then begin uploading the new RAM Disk and Kernel.

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.

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.

*As usual a big thanks to the iPhone Dev-Team for their hard work and contribution to the iPhone community.

Add Comment
akirawi - February 26, 2011 at 5:46pm
The title of this tutorial is wrong! iClarified wake up! that\'s for Iphone 4 not 3GS and mac not windows!
Gurvin - February 16, 2011 at 11:07am
iclarified standard is dropping... 1. The firmware file download link is for iphone 4 not 3gs 2. The tutorial says \"for windows\" yet the screenshots and instructions are for mac 3. In the screenshot too the iphone 4 firmware is shown instead of iphone 3gs. Waste of time
jorge - February 5, 2011 at 12:11pm
i cant download this link as an ipsw iPhone2,1_4.2.1_8C148a_Restore.ipsw it only does it as a zip file and wont show up when i try to restore my iphone. can anyone help
Thomas - February 4, 2011 at 8:34am
I got finally got this working. This is what I ended up doing. I ended up restoring in the official manner via itunes since I don\'t care what my baseband is, i don\'t need to unlock. The official restore will update BB to 05.15.04 on iphone 3gs so don\'t do it if you need to unlock. I then had to us the official IPSW I downloaded from apple for the choose your IPSW step of this tutorial. Don\'t us the IPSW from the link above if you did the official apple restore. This is found at %Userprofile%\\Application Data\\Apple Computer\\iTunes\\iPhone Software Updates it might be in different location for some people. Once i did that it was worked great. I for some reason could not downgrade must be a blob problem. Cydia says i have all blobs from 4.0 and greater stored and i uploaded before i restored. Not sure what\'s happening. i have seen at least 2 different addresses for saurik\'s server maybe one is incorrect.
Thomas - February 3, 2011 at 5:31pm
Hello. I have been at this for quite some time and have had zero luck. I get into DFU and when I hit waiting for reboot everything just stops. nothing get rebooted nothing happens at all. All i can do is reboot the thing normally. got redsn0w running in xp sp3 mode and as admin. Any suggestions would be great. thanks
197 More Comments
Follow iClarified
Apple to Announce Next Generation Apple TV in September Without Web TV Service?
Apple Releases Second Beta of OS X Yosemite 10.10.5 to Developers
Apple has released a second beta of OS X Yose...
Worms 3 is Apple's Free App of the Week [Download]
Apple has just named Worms 3, a fun strategy ...
Apple Releases iOS 8.4.1 Beta 2 to Developers
Apple has released iOS 8.4.1 beta 2 to develo...
Apple Patents New Method for Laser Cutting iPhone Sapphire Glass Covers
An Apple patent application has surfaced that...