Untethered jailbreak is available for iOS 5.0.1 firmware on iPhone3GS, iPhone4, iPhone4-CDMA, iPad1, iPod touch 3G, iPod touch 4G.
1. If you’re already on iOS 5.0.1 with a tethered jailbreak, you have two even choices:
Run redsn0w 0.9.10 over your current jailbreak (deselect “Install Cydia”)
Install the Cydia package prepared by the chronic devteam. It is called Corona 5.0.1 Untether. (tutorial)
2. If you are not on 5.0.1 yet, update now! If you unlock via ultrasn0w or gevey, make sure you update to 5.0.1 via a custom IPSW! See our guides for sn0wbreeze here. Once you’re at 5.0.1, use the latest redsn0w 0.9.10 to both jailbreak and untether.
These are step-by-step instructions on how to jailbreak iOS 4.2.1 on iPhone 3GS, iPhone 4, iPad, iPod Touch 2G, iPod Touch 3G, iPod Touch 4G using Greenpois0n for Windows. Tutorial for Mac OS X users is available here. All the steps are the same for all devices, we will cover iPhone.
Greenpois0n has been updated to support the iOS 4.1 and iOS 4.2.1 firmware. Use Limera1n if you want to jailbreak iOS 4.0, iOS 4.0.1, iOS 4.0.2.
Remember: Greenpois0n recommends a clean restore before continuing.
Unlockers: do not update to iOS 4.1 or iOS 4.2.1 if you need the unlock. Ultrasn0w does not support that baseband yet. The only exception is the iPhone 4. Experienced users can also try update to iOS 4.2.1 without upgrading your baseband by using TinyUmbrella. Start TSS Server->Start iTunes->Plug in your iPhone->Restore 4.2.1->Error 1013->Put phone into DFU Mode->Launch Greenpois0n.
We are not authors of this app. We do not promise that everything will go well, use this tutorial at your own risk.