Difference between untethered, tethered, and semi-tethered

A lot of people recently are confused as to what the difference is between a tethered, untethered, and semi-tethered jailbreak. iOS 4.2.1 is somewhat of a challenge for hackers, but the dark side always wins. This post will easily explain what these three things mean and how they may be important to you.

iOS 4.2.1 is in fact jailbroken, but it is a semi-tethered jailbreak for most newer devices.


An untethered jailbreak is where you can reboot your device without having to worry about it not booting up again.


A tethered jailbreak means you have to plug your device into your computer and re-run some jailbreaking software to get your iDevice up and running again. Failing to do so will leave your device at the “connect to iTunes” screen.


A semi-tethered jailbreak is where you’ll be able to reboot your device without needing a computer, but 99% of jailbreak related hacks, mods, and applications won’t work at all. BUT, sometimes your device may just get stuck at an Apple logo because of some problems with MobileSubstrate extensions. If this is the case, you’ll have to plug your iDevice into your computer and re-run some jailbreaking software to get everything going again.

Currently, the iOS 4.2.1 jailbreak for the iPad, iPhone 4, iPhone 3GS (new-bootrom), iPod Touch 3G/4G/MC is semi-tethered, so you’ll be able to boot it just fine (as long as you aren’t using MobileSubstrate) without the need of a computer.

Leave any of your questions below in the comments area, and I’ll try my best to answer them.

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  • http://www.iphone3gscreenrepair.com iPhone Screen Repair

    I have been trying to get this terminology down for quite awhile. I am currently using a semi-tethered jailbreak and really can’t wait until I can get my hands on the untethered version.

  • Ajundi

    Thank you that was clear and well written. I have a question regarding the latest jailbreak for 4.2.1 what software needs to be run in order to recover the jailbroken status after a reboot? does it depend on the tool used to jailbreak the device? if i used a modefied pawng tool to install 4.2.1 and the i reboot my ipad what should i run to be jailbroken again?

  • Mystery Date

    I’m new to jailbreaking, and I have a question regarding what might prevent a jailbroken device from becoming semi-tethered.

    I jailbroke 4.2 for one reason: My wife stopped using her iPad with the lock screen button functionality disabled. (She locks and unlocks a lot and finds the software switch annoying enough to stop using the device.) I used redsn0w 0.9.6b4 . After the jailbreak, I went into Cydia, installed the updates, and installed nomute. It worked, but it would not reboot into a normal mode by itself. It was fully tethered. It hung on the Apple logo.

    I restored the iPad (successfully) and re-jailbroke. This time, I did not install any updates. I only went into Cydia and installed nomute. It still hangs on the Apple logo and will not boot without the computer.

    I do not know what MobileSubstrate is, but something is keeping the iPad from being semi-tethered. Until either an untethered jailbreak is developed or Apple restores the screen lock switch, I’m kind of stuck. Semi-tethered would help a lot, as she could at least still use the device in a pinch if she runs out of battery. Any ideas? I have really done nothing more than install “nomute.”

  • http://gumballtech.com brian

    It’s still technically semi-tethered, but some of the extensions that you’ve installed will prevent the device from fully booting. Use the latest redsn0w.

  • Swarup

    hi, i am using ipod touch 4g ( version: 4.2.1)… i jailbreaked it… everything was just fine… but suddenly my installous got stuck and stopped working… and then i switched off my itouch n when i turned on the itouch it got stuck in the apple logo with a loading symbol… In order to restore it, I connected it to itunes n it also recognized my ipod saying that ( My ipod could not be restored with an unknown error 1119)…. Pls let me know wat to do…?

  • http://gumballtech.com brian

    Why would you need to restore? Just re-jailbreak, since you’re using a tethered jailbreak.

  • GreenasGrass

    i’ve been reading a bunch of sites to clarify the differences you’ve explained above and thanks for being so thorough. i’m trying to decide if i should and how i should jailbreak my ipod touch 4g (4.2.1), but i believe only the tethered or semitethered jailbreaks are available? how do i know if the jailbreak will be tethered or semitethered? if i decide to use the latest redsn0w tethered/semitethered and later update to an untethered jailbreak, will i lose all my jailbroken apps? thanks a lot!

  • http://gumballtech.com brian

    Your jailbreak will be semi-tethered. But, if you install any MobileSubstrate extentions (like WinterBoard or SBSettings), then it’ll be tethered because MobileSubstrate will prevent a semi-tethered boot.

    It’s unclear as to whether or not you’ll have to lose all of your apps when the untethered jaklbreak is officially released, but you most likely will have to restore to a clean install of iOS first.

    You can always give the beta jailbreak of redsn0w a try, but there are a few small bugs that have to be sorted out. http://blog.iPhone-dev.org/redsn0w

  • Eddierivera42@gmail.com

    I restored my ipod4g 4.2.1 from redsn0w tethered back to normal unjailbroken but I’m scared to restart it because I’m not sure if it will restart normally or it will get stuck on the apple logo help