How to Jailbreak iOS 4.2.1 using Greenpois0n [iPhone 4, 3GS, iPad & iPod]

Quick and easy tutorial on how to achieve and untethered jailbreak and unlock your iPhone 4 or iPhone 3GS using Greenpois0n. If you are looking for a iPhone 3G untethered jailbreak, it has been out for a while. Redsn0w 0.9.7b6 can do it (link below). Follow the instructions and leave any questions in the comments below.

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Note: Greenpois0n is Mac only as of right now (02-04-2011)
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Greenpois0n: bit.ly/fjZJ6k

TinyUmbrella link & Instructions (for preserving your iPhone 4 unlockable baseband): bit.ly/fZ3gqJ

PwnageTool (for creating custom 4.2.1 firmware that will preserve your baseband on an iPhone 3GS): bit.ly/eimvFb

redsn0w 0.9.7b6 (for iPhone 3G jailbreak and flashing the iPad baseband if you need to unlock and you are already on the 5.15 baseband): bit.ly/dT59QA

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Troubleshooting:

• If your device hangs at "Greenpois0n initialized", please delete it from your computer and redownload using the link below. It is an updated (fixed) version.

• if you open Loader and after it says loading sources, nothing comes up, it is because their server is getting slammed. You can use redsn0w (link below), browse for the 4.2.1 firmware and ONLY select "Install Cydia". It will work just fine and not interfere with your untethered jailbreak.

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