Jailbreak 4.2.1 iOS iPhone 4, 3gs, 3g, iPad, iPodTouch with Redsn0w 0.9.6b4 [ How to Guide ]

The bad new is that right now, the redsn0w 0.9.6b4 is a tethered or semi-tethered jailbreak for some devices (i.e. you will lose your jailbreak every time you reboot your iDevice, so you have to follow the following steps every reboot to have a jailbroken device )

Untethered Devices:

• iPhone 3GS (old bootrom)
• iPhone 3
• iPod touch 2G (Non-MC Model)

Tethered Devices:

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

NOTE: Those of you who rely on a carrier unlock stay away from Redsn0w and iOS 4.2.1.

GUIDE:

STEP 1: Download redsn0w 0.9.6b4, iOS 4.2.1 for your device(download links at the end).

STEP 2: Update to 4.2.1 firmware using the IPSW file you just downloaded via iTunes 10.1.

STEP 3: Launch Redsn0w 0.9.6b4, and browse for iOS 4.2.1 firmware final version

STEP 4: Select "Install Cydia" and click on "Next"

STEP 5: Now make sure your device is both OFF and PLUGGED IN to the computer before you click “Next”.

STEP 6: At this stage you will need to put your iPhone in DFU mode by holding “Power” button and then while holding the “Power” button, you will now have to hold “Home” button too. Now after few seconds release “Power” button but keep holding “Home” button until installation begins.

STEP 7: You will Get a Jailbroken Device on the latest iOS 4.2.1 as soon as the process ends.

STEP 8: This step is only for these devices iPhone 4, 3GS (New Bootrom), iPod touch 4G, 3G, 2G, iPad. While this is tethered jailbreak and whenever you want to do anything related to jailbreak like SSH your device, or running Cydia, you must first run your device in the so called “jailbroken state” on every reboot by using “Just boot tethered right now” option.