About the ‘Tethered’ Nature of the iOS 4.21 Redsn0w Jailbreak

Those looking to jailbreak their handsets under iOS 4.2.1 may want to hold off the hacking should they not be aware that redsn0w 0.9.6b4 provides a “tethered” jailbreak. The iPhone Dev Team has dedicated a few minutes of its time to post an update on their blog, explaining the particularities involved by the  redsn0w 0.9.6b4 jailbreak on the latest iOS version from Apple.

It is common knowledge among members of the jailbreak community that, after performing what is known as a “tethered” jailbreak, every time you reboot your iPhone or iPod touch, you have to connect (tether) it back to your computer, so that the jailbreak application can help it boot again.

A thoughtful post by OS X Daily includes the most recent example with redsn0w and iOS 4.2.1, complete with a set of instructions on how to get the device back into working state, once rebooted. The steps are enumerated below:

1- Connect the iOS hardware (iPod, iPad, iPhone) to your computer
2- Relaunch the same redsn0w application you used to jailbreak the device
3- Select the “Just boot tethered right now” option (shown in the screenshot above).
4- The jailbroken hardware will now boot with the aid of redsn0w

An even more comprehensive synopsis comes from the famous team of hackers who actually coded redsn0w, the only utility capable of providing the iOS 4.2.1 jailbreak at the moment.

The Team elaborates:

The notion of a “tethered” jailbreak is pretty new to many people, so here’s a quick rundown on what to expect:

1. If you’re on an iPhone3G, old-bootrom iPhone3GS, or non-MC ipt2g, life is easy. redsn0w installed an untethered jailbreak and so nothing below applies.

2. “Tethered” does not mean you cannot boot at all without PC/Mac assistance. If you have not installed any tweaks that hook into important programs like SpringBoard or CommCenter, your device will actually boot. However, jailbreak programs like Cydia won’t work (and Cydia may still have a white icon). Also, certain built-in apps that had to be moved by Cydia will fail (Safari being the most noticeable example).

3. If you’ve installed MobileSubstrate tweaks that hook into SpringBoard or other important programs, your boot will actually fail (you’ll get stuck at the Apple logo). You need to use redsn0w to “Just boot tethered right now”.

Finally, the iPhone Dev Team reminds members of the jailbreak community that “@comex and others are working on a way to untether the 4.2.1 jailbreak.”


This article has a purely informational purpose and doesn't, in any way, suggest that you should hack your Apple device.

Using hacks may render your device unusable, or may reduce the quality of your experience employing the respective device.

If you choose to download and install jailbreak tools, you will do so at your own risk. Unlocking / jailbreaking your iPhone / iPod touch / iPad / Apple TV may violate your warranty or the EULA with Apple and / or your cellular-service provider.