Before starting, let me put in two cents about the iPhone 3G and iPod 2G. The reason why I'm doing 4.2.1 in particular is because that is the latest firmware that either of these can update to. The cause for this is because the complexity of the newer iOSs has finally surpassed their processing power. Users of these devices have probably noticed that their device got buggier, laggier, and slower as they approached the final 4.2.1 update, which testifies to the fact that Apple must have thought that this was as far as they could go for compatibility for these devices. The untethered iOS 4 jailbreak also works for other devices, but is probably of no use for most users that are on a higher firmware.
Check to see if your device is running 4.2.1 by going to Settings>General>About: Version
If it is a lower version, download the proper firmware for your device from here, plug your iDevice into iTunes, click on the Device on the sidebar, hold Shift (Option on Mac) and click Restore. Browse to the firmware and restore your device to it. You should back up all files as they will be lost if restored. If your device was NOT previously jailbroken, you can do Shift + Update and no files will be lost, but it is recommended that a restore is done for the best outcome.
You must have one of the following devices:
- iPod Touch 2G, 3G, 4G
- iPhone 3G/3GS
- iPhone 4
- Verizon iPhone 4 (iOS 4.2.6)
- Apple TV 2
1. Download Greenpois0n
2. Plug in your device and backup your files in iTunes
3. Extract the .zip file for Greenpois0n (Right-click Extract or go in the folder and click extract)
4. Launch Greenpois0n and click Jailbreak (while your device is plugged in)
5. It will tell you to put you iDevice into DFU mode (follow the instructions on the screen which will be bold to tell you what the current step is);
- Press and hold the sleep button for two seconds
- Continue holding sleep, press the home button for 10 seconds
- Release the sleep and hold the home button for 15 seconds
- If you mess up it will give you an error message, just try again
7. Finish! Wait for your Device to reboot (don't mind any crazy things it does) and you should see the Cydia app appear as one of the apps.
8. If your not sure what jailbreaking is all about or what to do from here, visit this page!