Apple has released iOS 4.2 GM for developers and you can already jailbreak 4.2 iOS GM with Redsn0w 0.9.6 B2. Based on limera1n exploit, redsn0w 0.9.6 Beta 2 can jailbreak iOS 4.1 as well as iOS 4.2 Gold Master. An official update on iOS 4.2 jailbreak from iPhone Dev Team reads:
Today Apple released to developers the GM seed for 4.2. Tinkerers will find that yesterday’s redsn0w jailbreaks today’s 4.2 GM seed, simply by pointing redsn0w at the 4.1 IPSW (rather than the 4.2 one). Right now it mostly only makes sense for JB app developers to do that because many apps (including Cydia itself) need to be updated for 4.2. However, if all you want to do is enable afc2 (to use iFunBox or other file browsers), or to tweak settings like Battery % and Homescreen wallpapers, then go for it (if you have valid paid access to the GM seed). Be sure to uncheck the Cydia box, though! Ultrasn0w unlockers should stay very far away from this!!
To jailbreak iOS 4.2 GM with redsn0w, follow the steps below:
Before you Begin
You will need to download:
Redsn0w 4.1 iOS Jailbreak Guide
Step 1: Load the downloaded iOS 4.2 GM to your device [See how to load custom IPSW with iTunes]
Step 2: Launch redsn0w 0.9.6 Beta 2
Step 3: Browse for downloaded iOS 4.1 IPSW. If you have iPhone 3GS, redsn0w will notify you asking if you had a new bootrom device. If you rely on carrier unlock, you will lose it.
Step 4: Click “Yes”, then click “Next” to start the jailbreak process. You will be provided with following options to choose from:
- Install Cydia
- Just boot tethered right now
- Just enter pwned DFU mode right now
Select the ones you want. (Note: Cydia doesn’t work on iOS 4.2 as yet so you should rather uncheck “Install Cydia”).
Step 5: Now connect your device with computer and turn it off. Click next when done (be ready to perform some quick steps to put iPhone in DFU mode.
Step 6: Follow on-screen instructions to put your iPhone in DFU mode. You will need to:
- Hold Power button for 3 seconds
- Hold Power + Home button for 10 seconds
- Release Power button but keep holding Home button for approx 15 seconds.
Step 7: Now jailbreak process will begin, your iPhone will reboot and you will be able to track the progress from iPhone screen.
That’s all from your side. Your iPhone will reboot now and you will have jailbroken iPhone when it starts.