What a Tethered Jailbreak for iOS 4.2.1 Means

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Posted November 24, 2010 at 3:29am by iClarified

An explanation of what a tethered jailbreak is and what it means for those looking to jailbreak iOS 4.2.1, courtesy of the iPhone Dev-Team.

● 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.

● "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).

● 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".

Hopefully @comex will be able to untether the iOS 4.2.1 jailbreak soon!

What a Tethered Jailbreak for iOS 4.2.1 Means

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nick - January 4, 2011 at 2:21pm

hey i have a problem with my ipod touch 4g i think. after i jaibroke it with redsn0w because i have 4.2.1, my cydia app is now white and i can't open it up or safari. then i opened up redsn0w again to do the tether boot up thing and everything goes well until the screen says: waiting for reboot and my ipod isn't rebooting. someone please help i'm really a n00b at doing this. and i tried to downgrade it using tiny umbrella and that goes well during the downgrade process but at the end it just says an error occurred saying error 1606 or something like that. thanks for all of the help i really appreciate it.

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Anudeep - December 1, 2010 at 1:19pm

Hello All, I am stucked with apple logo at boot time. I dont want to boot tethered everytime if i restart using PC, what should i do ? Thanks in advance

Anudeep - December 1, 2010 at 1:53pm

I was checking other comments in this page, currently i should install springboard for manual restarting(which i don't want) but for shutdown and starting again only solution is to use redsnow with PC...And can any one tell me when untethered jailbreak for ios 4.2.1 will be released ? Is there any alternative other than connecting to PC ?

ltlredx - November 25, 2010 at 3:56pm

I agree w/ the person who stated this leaves more Qs than As. I've had my iPhone about a year & still don't feel comfortable enuf w/ the information provided to jailbreak my device. I don't want to jump into a "try this" situation & then find out another option would have been better. I've been looking for a comparison of the major jailbreaks available so I can make an informed decision but have not been successful in my search. If anyone knows of a good explaination of the differences (pros & cons) of each, please post a link!

Frank - November 25, 2010 at 10:45pm

There are no different jailbreaks. They are all using the same exploit and accomplishing the same task. Some of the tools provide extra features like allowing u to auto install packages or prevent a basement update. Basically if dont need an unlock and need a jailbreak right now and are willing to deal with the hassle of reconnecting to the computer if your phone is powered off, then jailbreak now. Otherwise stay on your current firmware and wait until untethered jailbreak is released.

ltlredx - November 26, 2010 at 3:52pm

LOL thanks for the kick in the ass. But seriously, I don't have a land-line so I can't afford to screw up my phone & end up stuck w/ a paperweight. Plus as this would be my virgin attempt I'd like to know which method is gonna be the best.

Quiksilver - November 26, 2010 at 4:24pm

If I were you, I'd wait for the 'untethered' (no cable) version to be available. Limera1n was adequate for 4.1 and I am also waiting for a similar solution for 4.2. If you want hassle-free jailbreaking, then wait for an untethered option. If you are still in 4.1 by all means, use Limera1n to jailbreak. Also, keep in mind that 4.3 has been announced for mid-december so maybe the parties responsible are waiting for 4.3 to be released.

ltlredx - November 26, 2010 at 6:20pm

TY for the kind advice. Did you use Limera1n? (hope I spelled it right).

Quiksilver - November 26, 2010 at 7:02pm

I used Limera1n for 4.1 then because of some problems with a certain app (WeatherIcon) I decided to restore my phone using iTunes. I didn't realize that 4.2 was made available so unintentionally I upgraded to 4.2. I downgraded and I am back to 4.1 and I am not planning to upgrade any time soon, or at least until an untethered solution comes along. If this was a iOS 5 released, then sure I would upgrade immediately, but 4.2 is nothing ground breaking so there really is no advantage to upgrade. I am staying on 4.1 for the time being.

Quiksilver - November 24, 2010 at 9:01am

This blog entry leaves more questions than answers. Sorry but I just acquired my first iPhone device and so I am quite new to the whole "jailbreak" scene, so forgive me for not being clear on a few things. Am I to understand that if I jailbreak with redsn0w, Cydia won't work at all? if so, what is the point of jailbreaking? Are there other apps like Cydia that will work fine? If I were to install say, for example, Lockscreen info and then I am asked to either Reboot the device or Restart Springboard, will the device not boot at all? In my case, unfortunately, I restored my phone because of an app that wouldn't quite uninstall itself and was automatically upgraded to iOS 4.2.1 ... if there any way to downgrade to 4.1? Thanks!

jim - November 24, 2010 at 10:18am

@quicklsilver, best bet is to head over to the dev team blog, it's a better place to start.

daryoon - November 24, 2010 at 10:40am

Yeah, the writing style of most hackers groups usually begs more questions than answer imho. ------------------------------------------------------- It's quite simple really. To answer your questions. Cydia will work with Redsn0w jailbreak. Otherwise, as you surmised...there wouldn't be a point to jailbreaking. However, at this time, Cydia as well as many cydia apps may need to be updated for full compatibility with IOS 4.2.1. ----------------------------------------------------------- With a tethered jailbreak, you'll only need to attached to a computer for reboots or cold boots from complete shutdowns. And only if you've install Cydia applications that has hooks into IOS, such as mobile substrate, etc... I believe Lockscreen info would be such an app. ------------------------------------------------------- Luckily, most of us rarely need to reboot or cold boot. The most common operation is a springboard restart, which works just fine. No need to tether your iPhone to a computer for that. ------------------------------------------------------- In the past, you can downgrade to previous iOS versions, only if you have your SHSH blob saved locally or on Cydia. I think this is still true at the moment. You can see which SHSH blobs Cydia server has saved for you at the top of the Cydia homescreen. It'll say something like: "SHSH: iOS 4.0.1, 4.0.2, 4.1." That means that Cydia has those keys saved for your particular iPhone, and thus will give the acknowledgment confirmation to the iPhone when it goes out and ask if it can install a older iOS software version. To reiterate, you can only downgrade iOS to versions you have the SHSH blob. Please google for step by step tutorials on how to do a downgrade. --------------------------------- Otherwise, it's most important to simply have some patience to give the hackers in the scene a chance to dissect the new iOS version and figure out exploits and the best course of action for a stable jailbreak. It'll also give all the application developers a chance to update their code to work on the latest iOS version. This part is no different than the official Appstore developer needing to do the same for their apps. ------------ To conclude, I personally use a tether jailbreak if that's currently the only option. Day to day, it's no big deal and no difference between a tether jailbreak and a non-tethered jailbreak. The only times that can cause an inconvenience is if: 1. your iPhone runs out of battery. 2. you have to turn it off for flights. 3. a serious crash that require a full reboot. With iPhone 4, I don't run out of juice anymore during my day to day usage. For flights, I usually put the phone in flight mode, rather than turn it off completely. For the third point, iOS rarely, ever crashes hard. Most of the time, it's simply a Springboard respring.

Quiksilver - November 24, 2010 at 10:48am

Thank you very much to those that posted informative information. I visited RedmondPie for a tutorial on how to downgrade to 4.1 and I did. No hassle at all. I will just wait until the untethered version of Limera1n or redsn0w is released before upgrading again.

ltlredx - November 25, 2010 at 4:01pm

Excellent explanation, Thank you! Can you take a stab at the question I posted please?

jipa - November 24, 2010 at 4:34am

thank for explanation...