tutorial for jailbreaking OS 4.2.1 (untethered)

Device's Supported:

• iPod Touch 2nd gen
• iPod Touch 3rd gen
• iPod Touch 4th gen
• iPhone 3gs
• iPhone 3g
• iPhone 4
• iPad 1st gen 

Firmware Supported:

 4.2.1

1. Restore to OS 4.2.1. If you are currently jailbroken tethered with redsnow You can safely run greenpoison over it. However this results in excess files in the file system that may slow your device down. Therefore it is ill-advised.

TO PROPERLY RESTORE:

For those who are not currently Jailbroken: (Regular Restore)

• Connect Your Device
• Open iTunes
• Open your Device's Tab
• Click RESTORE
• Follow the Remainder of the Restore Process.
• Once Restored, You may chose to restore an old iTunes Backup as long as the Backup WAS NOT from when you were previously jailbroken.

For those who are currently Jailbroken or have attempted to jailbreak, but failed: (DFU Restore)

• Connect Your Device
• Turn the device completely off. Slide to Power Off.
• Hold The Power/Sleep and Home buttons.
• Hold both until you hear the "recognize sound" from your computer.
• Release the Power/Sleep Button but continue to hold the home button.
• Your computer should find your device in DFU mode.
• The screen on your device should be completely black
• Open iTunes
• Open your Device's Tab
• Follow the Remainder of the Restore Process.
• Once Restored, DO NOT restore to a previous iTunes Backup.Choose to setup a new device

NOTE:At this time you should be completely restored. Close iTunes

2. Check your settings. On the ipod itself, Go to settings> general > about. You should be on OS 4.2

3. Download Greenpois0n RC5. Download it from Greenpois0n.com, or from this mirror

4. Extract. Extract the files from the compressed folder using winrar or 7zip

5. Connect. Connect your iDevice to your computer, via the USB charging cable, while the Device is powered ON. If it's already connected from the restore then just continue.

6.Close itunes. If itunes opens, close it.

NOTE: If you leave itunes open, Greenpois0n will close it. I have confirmed that Greenpois0n should be ran with iTunes closed. 

7. Run. Run greenpoisOn.exe AS ADMINISTRATOR

8.Turn Off. Turn the Device completely off. Press the power/sleep button and slide to turn off.

9.Prepare. In the GreenpoisOn Program: Click prepare to jailbreak.

10. Follow the directions in GreenpoisOn.They will be as follows:

-Get ready to start. 3 seconds

-Hold the power/sleep button for 3 seconds.

-While still holding the power button, press down the home
button at the same time. Hold for 10 seconds.

-Release the Power/Sleep button but continue to hold the home
button. Hold for 20 seconds (Should not take entire 20 seconds)
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11.Jailbreak. On the next screen in GreenpoisOn, click "Jailbreak".

12. Wait. GreenpoisOn will install and add "loader" to the home screen on your ipod.

13.Install Cydia. Open loader on your Device, and install cydia, This requires wifi. If you dont have reliable wifi, then wait until you do, partial Cydia installs will force you to start this over.