The following instructions will help you jailbreak iOS 4.2.1 on iPhone 4, 3GS, iPod touch 2G/3G/4G, iPad and Apple TV 2G using GreenPois0n.
NOTE: If your iPhone 4 relies on an unlock, do not update to iOS 4.2.1 yet as doing so will upgrade your baseband, making it impossible for now to unlock.
Download GreenPois0n from the link given below.
-http://bit.ly/g5iFTJ
-Greenpoiis0n RC5 2 is released, fixes problems, go ahead and just jailbreak.
DOwnload Greenpois0n RC5 2:
*http://bit.ly/hwjNQ2
Steps:
1. Restart your Mac
2. Plug in your iDevice after your Mac has restarted
3. Kill iTunes if it opens
4. Open Greenpois0n RC5 2
5. Hit Jailbreak and get ready
6. Follow the on screen instructions for DFU mode, make sure you do them on time!
7. CONTINUE HOLDING THE HOME BUTTON UNTIL YOU SEE SCROLLING TEXT!
8. You should be Jailbroken with the Loader app on your homescreen
9. Open up Redsn0w
10. Find your 4.2.1 iPSW
11. Click Next
12. Check mark INSTALL CYDIA
13. Contine the steps of Redsn0w
14. Your device will reboot and now your are Jailbroken on 4.2.1 with Cydia!
Download Redsnow:
http://bit.ly/fajexL
This is it! You are done !
To Jailbreak with Redsnow 0.9.7b6 go the link:
iphonejailbreaks.yolasite.com
FOR THE WEBSITE TO DOWNLOAD GREEN POISON GO TO www.greenpois0n.com
MAKE SURE NO UNLOCK PASSWORD IS APPLIED TO THE PRODUCT
FOR MORE INFO GO TO http://www.idownloadblog.com/jailbreak/
NEXT UP: HACKING UR Wii
source youtube