Jailbreaking and unlocking the iPhone 4 on 4.2.1 firmware using redsn0w
Updated: February 5, 2011
Who is this guide for?
- iPhone 4
- Cydia must have your 4.2 Beta 3 firmware SHSH on file.
- You must have access to the 4.2 Beta 3 firmware.
- I used iTunes 10.1.1.
- I used OS X 10.6.6.
Thanks again go out to the iPhone Dev Team for providing this amazing, and FREE program for
customizing the iPhone. You can visit their website here,
and their blog here.
You can read their
notes regarding this beta version of redsn0w
Attention: The creator of TinyUmbrella has posted a newer process for getting
the iPhone 4 onto 4.2.1 firmware while preserving your unlocked modem firmware. This process is
exactly the opposite of what I'm documenting here. He now proposes you restore instead of update
to get to 4.2.1. You do this at your own risk. I've already burned one of my iPhone 4s by
restoring and using TinyUmbrella. I then updated to preserve the baseband on another one of my
iPhone 4s and it worked that time using the instructions presented in this tutorial. If someone
wants to send me their iPhone 4 to risk on his new instructions I'd be happy to offer those
instructions as well. To read these alternate instructions simply go to the TinyUmbrella
website linked to below. One of the advantages to his method (if it works) is you wouldn't
need the 4.2 Beta 3 firmware or SHSH.
Download iOS 4.2.1 firmware for the iPhone 4 from Apple here:
Download redsn0w 0.9.7b6 from the iPhone Dev Team in the update 6 section of their blog post
Now place your 4.2 Beta 3 firmware file (you can obtain this file if you are a member of the
Apple Developer Connection, learn more here: http://developer.apple.com) with these files. You
should have these three icons on your desktop.
If your downloaded firmware file ends in .zip, rename it to end in .ipsw. Note: Safari likes to open
"safe" files by default. You must turn this feature off for this download to work correctly. Click
"Safari", select "Preferences", from the "Geneal" tab uncheck the box that says "Open "safe" files
after downloading". Otherwise just use Firefox to download this firmware file.
Double click the redsn0w file and it will place a folder on your desktop. Go into this folder and
place the redsnow.app file into your Applications folder on your computer. Overwrite any previous
Here I am on 4.1 firmware and 01.59.00 modem firmware
Launch TinyUmbrella and connect your iPhone. Ensure you have the 42b3 SHSH or else you won't be
able to jailbreak. It may be best to click the Save SHSH button to grab any and all SHSHs available.
You can download TinyUmbrella
You can also check for the 42b3 SHSH by launching Cydia.
Back in the TinyUmbrella program, click the Advanced tab and ensure the box is checked for "Set
Hosts to Cydia on Exit."
Another way to verify you have the correctly edited hosts file is to go to your Applications folder,
then go to the Utilities folder and launch the Terminal. Enter the following:
sudo nano /private/etc/hosts
You'll be prompted for your password so enter it.
If you see the line 184.108.40.206 gs.apple.com then you are good to go. This means that any requests
to the Apple verification server will instead be directed to the Cydia server. Ensure this line
does not have a # symbol at the beginning! Double check this, especially if you
happened to start the TSS server and then stopped it previously. If you screw this up your
modem firmware will be updated and you will be unable to unlock at present.
Launch iTunes. Press your option key while clicking Update.
Do NOT click Restore!
Navigate to your 4.2.1 firmware, select it and click Choose.
This message better say update and not restore.
The updating process will take several minutes.
A status bar on the iPhone will display the progress of the update.
When the process completes you'll receive a pop up with error 1013. Click OK.
Another pop up will appear. Click OK.
The iPhone will display the connect to iTunes graphic.
Go back to TinyUmbrella. Select the iPhone in the Recovery Devices section, then click the Exit
Recovery button. The iPhone will boot. If you launch Settings, and go to General, About you'll
see at this point that you are on 4.2.1 firmware and still have your 01.59.00 modem firmware.
Launch redsn0w. Click the Browse button.
A file browser will open. Navigate to your 4.2.1 firmware file, select it and click Open.
The ipsw should be identified. Click Next.
A pop up window will appear.
Redsn0w will present a few options. Install Cydia is already checked.
- Install Cydia is for adding the Cydia program to gain access to the jailbreak community of
- Jailbreak Monte (untether) is for jailbreaking 4.2.1 firmware which requires access to the
4.2 Beta 3 firmware.
- Install custom bundle is for adding your own .tgz or .tar.gz files to the jailbreak. When
you select this a file browser window will open.
- Just boot tethered right now - is for those that are already jailbroken via a tethered method
and need only reboot, not jailbreak all over again.
- Just enter pwned DFU mode right now - walks you through DFU mode used for restoring purposes.
Check the box for Jailbreak Monte (untether) and a pop up window will open. Click OK.
Navigate to your 4.2 Beta 3 firmware, select it and click Open.
Jailbreak Monte (untether) will now be checked. Click Next.
Turn off the iPhone, ensure it is connected via USB and click Next.
Instructions for entering DFU mode will appear. They start right away and go very quickly so try to
keep up! First hold down the Power (sleep/wake) button for three seconds.
Keep holding on to the Power button, and press and hold the Home button for 10 seconds.
Continue holding the Home button, and release the Power button.
Redsn0w will display various messages: Jailbreaking, Preparing Jailbreak Monte, JB Monte:
Extracting encrypted filesystem, Extracting kernel, Decrypting main filesystem, Extracting system
files, Finished preparation, Waiting for iPhone4, Fetching SHSH blobs, Exploiting with limera1n,
Uploading first stage, Waiting for reboot.
You'll see a graphic that says jailbreak data is being downloaded on the iPhone. Redsn0w will
display more messages: Uploading logo, Uploading ramdisk, Uploading kernel, Rebooting. You will see
the message: Waiting to send Jailbreak Monte files for about 2:30. In the mean time text will
scroll on the iPhone's screen.
You will see a few different messages (Installing base utilities, Replacing kernel, Flashing NOR,
Installing bundles, Activating, Syncing file systems, Moving Applications, Rebooting) on your iPhone
during the next couple minutes. The iPhone will reboot once this has finished.
Done will appear in the program.
Launch Cydia. Don't worry about the icon being white right now. The next screen will state that
the file system is initializing for about one minute. The iPhone will then respring. Launch
Cydia again. My screen freaked out at this point (it's done it before using this jailbreak).
Cydia will show you have updates and the Apple logo and possibly the spinning wheel will appear and
will flicker. I pressed the Upgrade Essential button. Confirm the installation at the next
Press the Reboot Device button. The Cydia icon should look normal now. Launch it.
Press the Search button. Enter ultrasn0w.
Install the program. Press Reboot Device.
You'll most likely receive this message next. I have no idea what the ramifications are.
Here I am on 4.2.1 firmware and 01.59.00 modem firmware. If you do not have a carrier signal try
rebooting (several times). You may also need to launch Settings, press General, press Network and
then turn off your 3G service for ultrasn0w to work. This is normal.