Chronic Dev Team released greenpois0n to jailbreak iOS 4.2.1 for iPhone 4, iPhone 3GS, iPhone 3G, iPod Touch 4G,iPod Touch 3G and iPad.

In this guide, we will take you through the step by step procedure to jailbreak your iPod Touch 4G or iPod h Touch 3G or iPod Touch 2G on iOS 4.2.1 using greenpois0n.

Here are some important points to note before you proceed:

• Please note that jailbreaking your iPod Touch may void your warranty and hence proceed with caution and at your own risk.
• This guide is meant for iPod Touch 4G, iPod Touch 3G, iPod Touch 2G users only. iPhone 4, iPhone 3GS and iPhone 3G users can checkout this step-by-step guide.
• Greenpois0n supports iOS 4.2.1 and iOS 4.1. So you need to first update your iPod Touch with iOS 4.1 or iOS 4.2.1 to use greenpois0n.
• Please note that this guide is only meant for Mac users as greenpois0n is currently available for Mac only. Windows users can checkout this step-by-step guide.
• Do not forget to backup your iPod Touch before you proceed. You can refer to this post for instructions on how to backup your iPod Touch.
• Please ensure you are running latest version of iTunes, iTunes 10.1 or later.
• After the jailbreaking process is complete, do not forget to checkout our article on tips to keep your iPod Touch secure.

You can follow these step-by-step instructions to jailbreak your iPod Touch:

1. Go to http://www.greenpois0n.com/ and click on the Mac icon to download the latest version of greenpois0n. If the greenpois0n site is down then you can checkout this mirror site. Note: If you’ve downloaded it earlier, we would recommend you to delete the older file and download it again to ensure you have the latest version of greenpois0n.
2. Double click the greenpois0n zip file to extract the file and double click greenpois0n to launch the application.
3. Next connect your iPod Touch to the computer and power it off.
4. Then click on the Jailbreak button.
   
5. You will be prompted to put your iPod Touch in DFU mode. Greenpois0n will take you through the necessary steps.
6. Press and hold the Sleep/Wake button for 3 seconds.
   
7. Keep holding the Sleep/Wake button and also simultaneously also press and hold the Home button for 10 seconds.
   
8. You will then be prompted to release the Sleep/Wake button but continue holding the Home button.
   
9. Once the iPod Touch enters DFU mode, greenpois0n will start the jailbreaking process, but remember to keep holding the Home button.
   
10. Once the jailbreaking is complete, you will be prompted to release the Home button.
    
11. Click Complete button to close the application. You should see text in verbose mode scrolling on your iPod Touch’s screen.
12. Your iPod Touch will reboot. After it has rebooted, you’ll notice that there is a new Loader application on your iPod Touch’s home screen.
    
13. Tap on it to launch it. Select Cydia and then tap on Install Cydia button.
    
14. After you have successfully installed Cydia, you can uninstall the Loader application as it is no longer required. Tap on the Options button and then Remove Loader.app button to uninstall it.
    
15. That’s it, your iPod Touch is successfully jailbroken and you should see Cydia on the homescreen. Reboot your iPod Touch and launch Cydia to install the latest updates.
    

If you’re new to the jailbreaking world and wondering what to do after jailbreaking your iPhone, checkout our jailbreak apps category page to find out the apps you can install on your iPhone using the Cydia app, which is the App Store for jailbreak apps.

Troubleshooting steps:

• You can checkout our post with all the troubleshooting tips if you had problems jailbreaking your iPod Touch.
• If you had problems jailbreaking your iPod Touch when greenpois0n was released, please note that Chronic Dev Team has released greenpois0n RC5_2, which fixes various bugs including the issue where it used to get stuck at “Greenpois0n Initialized”.
• If you don’t see Cydia in the Loader app after launching it then you can install Cydia using Redsn0w 0.9.6 RC8 (download link). You should just tick Cydia from the list of options and don’t use the Monte option.
• Greenpois0n recommends a clean restore so if the above steps don’t work then you can try to restore your iPod Touch if you desperately want a jailbreak as it is not ideal.
• If you are facing a problem where greenpois0n opens and quits immediately then try the steps mentioned above after downloading greenpois0n RC5_b3 (this guide has been updated with the link to greenpois0n RC5_b3).

Update:

Chronic Dev Team has released greenpois0n RC5_b3, which now supports Mac OS X 10.5.x or later so updated the link to mirror site to point to the latest version.

As always, let us know how it goes and if you have a tip that helped you jailbreak your iPod Touch using greenpois0n successfully then do share it in the comments section below.

[via iClarified]