Tutorial: How to Jailbreak Your iPhone iOS 4.2.1 with RedSn0w

 RedSn0w was recently updated to jailbreak iOS 4.2.1. While this is excellent news, it doesn’t come without its drawbacks as only the iPhone 3G, older iPhone 3GS, and non-MC iPod touch 2G get the untethered jailbreak.

Other devices get a tethered jailbreak, which means that every time you reboot your iPhone, you will have to plug your iPhone in your computer, and launch RedSn0w to start your iPhone. Hopefully the Dev Team will come up with a way to bypass this soon.

If you are an unlocker, you should not update to 4.2.1 yet. You will lose your chances of unlocking. Wait for PwnageTool, which should be updated relatively soon.

This step by step guide will show you how to jailbreak your iPhone iOS 4.2.1 with RedSn0w. This tutorial was made using an iPhone 3GS but the steps are the same, no matter what device you are using…

check link here.....
http://www.iphonedownloadblog.com/2010/11/23/tutorial-how-to-jailbreak-your-iphone-ios-4-2-1-with-redsn0w/