The first Redsn0w to jailbreak with Cydia and all devices MobileSubstrate iOS 4.2.1 was officially released.This is the Redsn0w 0.9.6b4, which is based on the Limera1n bootrom Geohot exploit, which has released all iDevices permanently.
However, using 0.9.6b4 Redsn0w, each time you reboot the iDevice, you need to boot in “Jailbroken State. “ Thus, this jailbreak is only available for iPhone 3G (New Bootrom) iPhone 4, iPad, iPod Touch 2G(Model MC), iPod Touch 3G and 4G iPod Touch. It can also be used by earlier devices such as iPhone 3G(Old Bootrom), iPhone 3G and iPod Touch 2G (Model Non-MC), without having to continuously reboot.
Here, we present a step by step guide to jailbreak the 4.2.1 iOS with Redsn0w 0.9.6b4. If you have an unlocked iDevice, we recommend you refrain from doing these steps, although, in general, TecnoLatino.com not responsible for any damages or losses that you suffer for your mobile phone due to the implementation of this guide, whose purpose is merely informative.
Step 1: Download 4.2.1 IOS for your device.
Step 2: Upgrade or restore the IOS firmware 4.2.1 using the IPSW file you downloaded in the previous step using iTunes 10.1.
Step 3: Start Redsn0w 0.9.6b4 and take it to firmware 4.2.1 iOS to proceed with the jailbreak.
Step 4: Now select “Install Cydia“and click”Next. “ Optionally (if available) can also select any other options you want.
Step 5: Make sure your device is turned off and plugged into the computer before clicking “Next. “
Then you will be presented a screen where you must press the power button (Power), and then, together, press the start button (Home). After several seconds, release the power button and continue holding the home button until the facility begins.
Step 6: When this procedure is complete, your iPhone or iPod will reset automatically and operate with iOS firmware 4.2.1.
Step 7: If you own an iPhone 4, 3G (New Bootrom) Touch iPod 4G / 3G / 2G or IPAD, when you want to run Cydia, SSH or do any other transaction relating to jailbreak your device, you must first run it in the “Jailbroken State“for each reboot, using the option Redsn0w”Just boot tethered right now. “