How to Jailbreak iPad, iPhone and iPod iOS 4.2.1 with Redsn0w 0.9.6b4

On November 23rd, 2010, The iPhone Dev Team released Redsn0w 0.9.6b4.
Redsn0w 0.9.6b4 brings about the first jailbreak, with a working Cydia app and MobileSubstrate,
to all iOS 4.2.1 devices.

The one nuisance is that it's a tethered jailbreak for the newest devices. Having
a tethered jailbreak means you will have to connect your jailbroken iOS device,
to your computer, and execute the Redsn0w 0.9.6b4 program again in order 
to regain your jailbreak status on every reboot.  This "re-jailbreaking" process
actually takes much less time than the initial jailbreaking of your device.

Redsn0w 0.9.6b4 provides:
    
1) an untethered jailbreak of iOS 4.2.1 for:

• iPhone 3G
• older iPhone 3GS
• non-MC iPod touch 2G

2) a tethered jailbreak for:

• iPhone 3GS (new bootrom)
• iPhone 4
• iPad
• iPod touch 2G (MC model)*
• iPod touch 3G
• iPod touch 4G

      * To find out which model you have, go to Settings => General => About, and then scroll down to  "model".
          The model number there will start with MC (MC model) or MB (not MC model).

MuscleNerd of iPhone Dev-Team has confirmed that the next version of Redsn0w
will be released just before Christmas 2010 and will include an option which will
allow you to untether your iPhone jailbreak on iOS 4.2.1 without having to restore
your device.

WARNING: Those of you who rely on a carrier unlock MUST STAY AWAY from

Redsn0w and iOS 4.2.1.

Follow the step by step instructions posted below to jailbreak iOS 4.2.1 with Redsn0w 0.9.6b4: Step 1: Download iOS 4.2.1 for your version of iOS device.

Download iPhone 4 IPSW Download iPhone 3GS IPSW Download iPhone 3G IPSW Download iPad IPSW Download iPod touch 2G IPSW Download iPod touch 3G IPSW Download iPod touch 4G IPSW

Step 2: Download Redsn0w 0.9.6b4 for your system:

Download Redsn0w 0.9.6b4 for Mac Download Redsn0w 0.9.6b4 for Windows

Step 3: Using iTunes 10.1 or newer, Update/Restore to iOS 4.2.1 firmware using
the IPSW file you just downloaded. Your device needs to be connected to your
computer via USB for this step and beyond.

(If you are using the 'Restore' option to upgrade your device, hold down 'Alt' key and click on Update 
or Restore, then navigate to the IPSW file you just downloaded and double-click/select) 

Step 4: Start Redsn0w 0.9.6b4 and point it to iOS 4.2.1 firmware to proceed
with the jailbreak.

Step 5: Now select “Install Cydia” and click “Next”.

Step 6: Make sure your device is both OFF and PLUGGED IN to the computer, via USB, before you click “Next”.

Step 7: You will now be instructed to follow a few steps in order to place your device in to the DFU mode by: Quickly hold down the "Power" or "Sleep/Wake" button located on the top of your device. Keep holding down the "Power" or "Sleep/Wake" button AND hold down the "Home" button, for 10 seconds. Release the "Power" or "Sleep/Wake" button but keep holding “Home” button for 15 seconds or until installation begins.

Step 8: Sit back and enjoy while redsn0w will do all the rest for you. Once done, your iPhone or iPod touch will restart automatically and you will find it jailbroken on the latest iOS 4.2.1 firmware.

The Following Step 9 is for iPhone 4, 3GS (New Bootrom), iPod touch 4G / 3G / 2G, iPad ONLY:

Step 9: This step is for when you have to reboot your device or your battery goes dead and you "lose" your jailbreak. Simply plug your device into your computer Start Redsn0w Check the option to “Just boot tethered right now”. (See below) Follow the remaining steps to place your device in the DFU mode.

DOWNLOADS FOR THIS TUTORIAL

Download iPhone 4 IPSW Download iPhone 3GS IPSW Download iPhone 3G IPSW Download iPad IPSW Download iPod touch 2G IPSW Download iPod touch 3G IPSW Download iPod touch 4G IPSW

Download Redsn0w 0.9.6b4 for Mac Download Redsn0w 0.9.6b4 for Windows