iOS 4.2.1 Jailbreak – the software name is Redsn0w 0.9.7b1 (installation steps)
This version of iOS 4.2.1 Jailbreak has been released by Dev Team and is named Redsn0w 0.9.7b1. Redsn0w Jailbreak works on iPhone 4, iPod Touch 4G and on iPad.
To run Redsn0w 0.9.7b1 you must have installed on your Apple iPhone 4, iPod Touch 4G or iPad the 4.2.1 version of iOS.
If you don’t have the iOS 4.2.1 ipsw installed on your device, check the list below to find the necessary file for your Apple device:
Download iOS 4.2.1 ipsw for iPhone 4 here
Download iOS 4.1 ipsw for iPod Touch 4G here
Download iOS 4.2.1 ipsw for iPad Wi-Fi/3G here
You must have a developer account with Apple to get iOS 4.2.1 beta 3, your Signature Hash files saved (on Cydia server) for iOS 4.2.1 beta 3 and MAC OS X.
Steps to follow for iOS 4.2.1 Jailbreak with Redsn0w 0.9.7b1.
– download Redsn0w 0.9.7b1
– download usbmuxd
– extract the usbmuxd arhive, and start MAC OS X Terminal app from Applications -> Utilites folder
– now point the Terminal app to the python-client directory in usbmuxd folder and enter the commands in each line:
chmod +x tcprelay.py
./tcprelay.py -t 22:2222
– Usbmuxd will make the Apple USB cable work with the jailbreak application
– run Redsn0w 0.9.7b1 and point it to the official iOS 4.2.1 firmware file
– click next, select Jailbreak Monte option and browse to the downloaded iOS 4.2.1 beta 3
– Redsn0w 0.9.7b1 will now process jailbreak and in the next step choose the option Jailbreak Monte (untether)
– now enter into the DFU mode by following the on screen instructions.
– Redsn0w 0.9.7b1 will complete the jailbreak process and will start your device in the untethered mode
NOTE: Remember, this version is a little unstable. As always, err on the side of caution, so you might want to make a backup of your device’s data before installing any unofficial software update or upgrade.