This jailbreak tutorial is only for iPhone 3GS owners with old bootroms that have SHSH saved for iOS 3.1.2. This method does not work for iPhone 3GS with new bootrom or on any other terminals/firmware versions. This tutorial NU does activation, so if you need activation you will have to use the phone operator's card on which the phone is blocked or a universal card.
PwnageTool can only be used on Mac OSX, there is no version for Windows.
Cydia does not work on iOS 4.2 jailbroken, so it would be good to install OpenSSH and OpenSSL when making this custom firmware. You have to install all the .deb files manually via SSH.
iOS 4.2 updates the baseband, so if you need decoding, DO NOT update! I DO NOT recommend this tutorial to people who have advanced knowledge about jailbreaking/installing files via SSH and working with PwnageTool/Mac OS X.
Before starting this tutorial, make sure you have iOS 3.1.2 jailbroken with redsn0w/blackra1n installed on your phone.
Step 1
Download PwnageTool 4.01 from here: [download id=”59″]
Download this custom firmware bundle from here.
Download iOS 4.2 from the Apple website, from the section dedicated to developers.
Step 2
Unzip PwnageTool and the archive with that custom firmware bundle on the desktop. Right-click on PwnageTool, select "Show Package Contents" and navigate to: Contents/Resources/FirmwareBundles/ then copy there the firmware bundle from the archive downloaded in step 1.
Step 3
Open Pwnagetool, select Advanced mode, select iOS 4.2 downloaded in step 1 and follow the steps of here to make a custom ipsw with PwnageTool. This modified version of PwnageTool does not activate the phone nor does it keep the baseband, so you will not have the phone ready activated after installing it, nor will you be able to install any decoding program through it.
Step 4
After you have made that custom ipsw, hold down the Option key while you click on restore to select the custom firmware made.
After iTunes finishes restoring, you will have iOS 4.2 installed for iPhone 3GS.
