How to jail break your iphone 3gs 4.2.1

Go to GreenPois0n.com Spelt with the number 0 at the end

Here you have 3 options to

Mac      Linux       Windows

Choose which ever is relevant to you but for this article we are using windows.

Download the file and extract it to your desktop. Run the file and plug your iPhone into your laptop to begin.

I must stress you do need the update of 4.2.1 or this will not work.

Anyway once plugged in the program on your laptop will give you a series of commands. The commands are simple, Hold sleep for 10 seconds, Then sleep and hold, release hold etc.

If you have done it correctly then it will start the jail-break and you can see that on your screen.

Once rebooted you will see an app displayed on your iPhone called loader. Go onto this app and there will be a file called Cydia which you will need to download.

Once Cydia has downloaded you need to go into it and select Sources. Once selected you need to enter and search the following sources. 

http://cydia.hackulo.us

http://sinfuliPhonerepo.com and download both.  

This will then Jail-Break your iPhone and you can download pretty much what you want, Have fun    :::::: :-)