NOTE: Users who rely on ultrasn0w unlock MUST stay away from Redsn0w.
Step 1: Download iOS 4.3.1 for your device (download links at the end)
Step 2: Update/Restore to iOS 4.3.1 firmware using the IPSW file via iTunes 10.2.1. (NOTE: If at this step you encountered Error 1013 and the iPhone is in an endless Recovery Mode, use this method to kick out from the Recovery Mode)
Step 3: Start Redsn0w and point it to the official iOS 4.3.1 firmware file.
Step 4: Now simply select “Install Cydia” and click “Next”.
Step 5: Now make sure your device is both OFF and PLUGGED IN to the computer before you click “Next”.
At this stage you will be presented with a screen where you will be guided on how to enter DFU mode. Quickly hold “Power” button and then while holding the “Power” button, you will now have to hold “Home” button too. Now after few seconds release “Power” button but keep holding “Home” button until installation begins.
Step 6: Wait shortly. Once done, your iPhone, iPad or iPod touch will restart automatically and you will find it fully jailbroken (untethered) on the latest iOS 4.3.1 firmware.
Download Redsn0w 0.9.6rc12 (Mac) <-- Latest Apri. 10, 2011
Download Redsn0w 0.9.6rc9 (Windows)
Download Redsn0w 0.9.6rc9 (Mac)
Download iOS 4.3.1 for iPhone, iPad and iPod touch
Download iTunes 10.2.1 for Windows / Mac OS X
[SOURCE: Jailbreak iOS 4.3.1 Untethered with Redsn0w 0.9.6rc9 for iPhone /iPod Touch / iPad]
WARNING WARNING [Source: Dev Team] — ultrasn0w users don’t update yet! We need to first release an update to ultrasn0w that fixes some incompatibilities when FW 4.3.1 is used on the older basebands supported by ultrasn0w. And remember once we do fix ultrasn0w for 4.3.1 (we’ll announce it here and on twitter), you must only get there via a custom IPSW from PwnageTool, Sn0wbreeze or xpwn! Don’t ever try to restore or update to a stock IPSW, or you’ll lose the unlock!
For everyone else, redsn0w is the easier program to use (and redsn0w runs on both Mac and Windows). Please check out places like iClarified for some excellent guides on how to use both PwnageTool and redsn0w.
FOR MAC USERS
iPhone Dev Team has just released PwnageTool 4.3 to bring untethered jailbreak for iOS 4.3.1 with the help of i0n1c's untethered exploit. PwnageTool allows you to create full untethered iOS 4.3.1 custom firmware files. As you know PwnageTool is a Mac OS X tool, check out the supported devices after the jump.
iPhone 4, 3GS iPod Touch 4G, 3G iPad 1 (Unfortunately iPad 2 still not supported) Apple TV 2G. Important
Note: If you rely on ultrasn0w unlock, you MUST use this version of PwnageTool which creates custom 4.3.1 firmware with preserving the unlockable baseband to be able to unlock your iPhone again using ultrasn0w 1.2
Download PwnageTool 4.3 for Mac
Download iOS 4.3.1 for all iPhone, iPod touch, iPad and Apple TV 2G