iPhone Dev-Team has released an updated version of Redsn0w (v0.9.6b4) to jailbreak iOS 4.2.1 on iPhone 4/3GS/3G, iPod Touch 4G/3G/2G & iPad (Wifi+3G). Unlike Cydia that comes with PwnageTool 4.1.2 and Redsn0w 0.9.6b3, Redsn0w 0.9.6b4 comes with an updated version of MobileSubstrate and Cydia which doesn't crash anymore.
Note that Redsn0w 0.9.6b4 will do a semi-tethered jailbreak on iPhone 4/3GS (New Bootrom), iPod Touch 4G/3G/2G (MC Model) and iPad. Semi-tethered jailbreak means inorder to SSH (Win | Mac) into your device or use Cydia, you must boot into jailbroken state using "Just boot tethered right now" option in Redsn0w. All other iPhone 3G, iPhone 3GS (Old Bootrom) and iPod Touch 2G (non-MC Model) users can enjoy full untethered iOS 4.2.1 jailbreak on their devices. Though Redsn0w 0.9.6b4 will jailbreak iOS 4.2.1 on all of the said devices but it'll also upgrade your baseband to 05.15.04 on iPhone 3GS/3G and 03.10.01 on iPhone 4. Both of these basebands are yet to be unlocked by the newest version of Ultrasn0w unlock tool.
Steps to Jailbreak iOS 4.2.1 on iPhone 4/3GS/3G, iPod Touch 4G/3G/2G & iPad with Redsn0w 0.9.6b4:
*Find download links at the end of post
- *Download iTunes 10.1
- *Download Redsn0w 0.9.6b4
- *Download stock iOS 4.2.1 IPSW for your iDevice.
- Connect your device to your PC or Mac OS X and restore to iOS 4.2.1 using iTunes 10.1.
- Once iOS 4.2.1 is successfully restored on your iDevice, run Redsn0w.exe and click on the "Browse" button. Select iOS 4.2.1 IPSW you downloaded in step 3.
- Once Redsn0w has successfully identified the firmware file, click on "Next" button to patch the firmware.
- Select Cydia from the options and click on the "Next" button.
- Turn off and plug your device to your computer.
- Connect your iPhone in recovery mode. For that you will need to quickly hold "Power" button , after holding the "Power" button for 3 seconds, you will now have to hold "Home" button for 10 seconds. After that release "Power" button but keep holding "Home" until the installation automatically begins.
- Now leave the rest for Redsn0w, your device will reboot automatically once the process is completed.
For iPhone 4/3GS (New Bootrom), iPod Touch 4G/3G/2G (MC Model) and iPad Users:
Once you are done with the jailbreak process, all iDevices except iPhone 3G, iPhone 3GS (Old Bootrom) and iPod Touch 2G (non-MC Model) need to boot into jailbroken state by using "Just boot tethered right now" option as shown in the screenshot below:
Once you have successfully booted your device into jailbroken state, you can use Cydia and SSH into your device easily.