Jailbreak iOS 4.2.1 Using Greenp0ison ( Guide )

How to Jailbreak iOS 4.2.1 using Greenp0ison ? Well its the easiest way to Jailbreak, other Jailbreak methods can be done with a custom IPSW ( Firmware ) but that requires another post ( Links at the end of post ) . To be qualified you need to have iOS 4.2.1 installed on your device or it will not work ! For Unlockers be careful on how you Upgrade your firmware using iTunes ( Why ? ) Because iTunes Upgrades the Baseband & you will be stuck with a locked iPhone .
Read the instructions carefully then apply the Jailbreak . Good Luck to everyone  .

Download Greenp0ison ( Official Links ) :

Greenpois0n 1.0 RC6.1 ( Windows ) 
Greenpois0n 1.0 RC6.1 ( Mac )

 Supported iDevices:

•    iPod Touch 2G (all bootroms)
•    iPod Touch 3G
•    iPod Touch 4G
•    iPad 1G
•    iPhone 3Gs (all bootroms)
•    iPhone 4
•    iPhone 4 Verizon
•    Apple TV 2

 Requirements ( Check this ! )

•    A supported device (see above)
•    The device should run iOS 4.2.1 (4.2.6 for iPhone 4 Verizon). Please check on the device in the Settings -> General -> About page.

•    At least Win XP,Vista,Win 7,Mac .
•    A working internet connection ( WiFi Connection Recommended for the iDevice )

 If your device is running an older version, please upgrade iOS first using iTunes.( Unlockers be careful on Upgrading with iTunes because iTunes will Upgrade your Baseband then you will not be able to Unlock your iPhone )

    *** If you want to SIM Unlock, preserve your baseband using TinyUmbrella ( Windows Users ) ''iPhone 4 only'' or PwnageTool ( Mac Users ) ***

 Notes ( Checks this also ! )

• If your device is jailbroken with iPhone Dev Team's Monte, please restore the device using iTunes first.
• If Cydia doesn't show up after Loader, you may need to reboot the device
• This version of greenpois0n doesn't include a patched activation system. You'll need to activate your device using iTunes
• WE DO NOT SUPPORT PIRACY ! ( Meaning that Greenp0ison will not Hacktivate your Device, you have to use the normal Activation method, or if you want to Hacktivate you need to use Sn0wbreeze to build a custom Firmware that is Hacktivated )

 Instructions :

1. Plug the device to your computer using the USB cable.
2. Quit iTunes if it shows up.
3. Start greenpois0n.app.
4. Follow instructions.
5. The device will boot a 1st time with verbose text on screen ( Hacker style like Hollywood ). This operation will install the jailbreak on the device.
6. The device will reboot normally .
7. Start the Loader application (green icon on the SpringBoard), and follow instructions to install Cydia.

This is the Official Greenp0ison method , I just illustrated minor things to make them understandable by Noobs or Beginners . You can find also other Useful posts :

Jailbreak Quick Tool ! 

Jailbreak with a Custom Firmware ( IPSW ) Full Guide ! 

All Custom Firmware (IPSW) Untethered+JB 4.2.1 To 4.3.3 iP4,3,3GS 

Having Problems With Jailbreak ? 

How To Jailbreak For Dummies (Tutorial) 1st Edition ! 

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