The Official Tethered Jailbreak FAQ

Discussion in 'Jailbreaks and iOS Hacks' started by thelatinist, Dec 9, 2009.

  1. thelatinist macrumors 603

    thelatinist

    Joined:
    Aug 15, 2009
    Location:
    Connecticut, USA
    #1
    At least once a day a poster on this board asks what a tethered jailbreak is. This thread aims to provide a central location to which such posters can be directed, with clear and concise answers to these questions.

    So, what's a tethered jailbreak?

    A tethered jailbreak is a jailbreak which leaves the jailbroken phone unable to boot without the help of a computer. Any time such a phone is completely powered off, restarted (for instance after installing certain jailbreak apps) or its battery dies, it must be plugged into a computer and the jailbreaking application must be re-run to get it past the Apple logo boot screen. Such a phone does not lose its jailbreak, and all customizations will be preserved, but the phone will not be able to boot past the Apple logo screen on its own.

    Why do some phones only support a tethered jailbreak?

    That requires a little more explanation. Every iPhone has a chip in it which contains a tiny program called iBoot. iBoot is the phone's bootloader, the program that tells the phone how to load the operating system. During this process, iBoot checks the OS to make sure that it is the official version provided by Apple. If it is not the correct version (for example, because it has been modified by a jailbreak), it will normally refuse to boot your phone.

    Clever hackers discovered a weakness in iBoot (which they called the 24kpwn hack) that allowed them to inject their own code into iBoot to bypass this security check and boot a jailbroken version of the OS that iBoot normally would not boot. Basically, by crashing iBoot at a certain point in the boot process, they could inject 24kb of their own code and iBoot would think it was perfectly normal. This code disabled the security check, and it was the only known way of getting a jailbroken iPhone to boot itself.

    As of sometime in October, Apple started shipping iPhones with a new version of iBoot. This new version patched the 24kpwn hack, meaning we lost our only known way of modifying iBoot so that it can boot a modified version of the OS. It is still possible to use a computer to bypass iBoot, but one can't convince iBoot to bypass itself. This is why the new iPhones can have only a tethered jailbreak.

    Does my phone have the new version of iBoot?

    There are ways to check. If your iBoot version is 359.3, then you can have an untethered jailbreak (whether on 3.1.2 or any other version of the OS); if it is 359.3.2 or 359.3-2 you cannot, at least not now.

    If you are considering buying a new or used 3GS and cannot find out the iBoot version, you should at least check the 4th and 5th digits of the serial number, which represent the week of manufacture. For our purposes, the lower this number is, the better. Because different plants began using the new version of iBoot at different times, there is no firm rule for which phones will be safe; in general, however, a phone manufactured in week 36 or earlier will have an untethered jailbreak, 37-40 is iffy, and 41 and higher will almost certainly be tethered. These rules do not apply to re-manufactured phones, which are given new serial numbers but which have older components and may have the older version of iBoot.

    Can I still jailbreak my phone?

    Yes, all iPhones are jailbreakable. The tethered jailbreak is more a problem of inconvenience, since you might occasionally be stuck without a phone until you can reach a computer. The good news is that the iPhone is designed to run without rebooting or completely powering off under normal use; some people go weeks without the need to restart their phone. Only you can decide whether the advantages of a jailbreak outweigh the inconvenience of being tethered, however.

    Will there ever be an untethered jailbreak again?

    Ever is a very long time and iPhone hackers are brilliant, so it is always possible that a solution will be found. Right now, though, there is no prospect for a new iBoot hack, and it is therefore impossible to predict when or even if one will be found. For now you should assume that any phone with the new iBoot is not untetherable.
     
  2. secretanchitman macrumors 6502

    secretanchitman

    Joined:
    Sep 13, 2007
    #2
    looks like im one of the lucky ones...i have a week 43 and i have the older iboot :)
     
  3. thelatinist thread starter macrumors 603

    thelatinist

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    Aug 15, 2009
    Location:
    Connecticut, USA
    #3
    Did you get this phone as a replacement?
     
  4. KingHuds macrumors 6502

    Joined:
    Aug 2, 2008
    #4
    I have the 359.3 bootrom, yet my phone keeps suddenly losing service, then after a restart it requires activation again. Whats up with that?
     
  5. dhlizard macrumors G4

    dhlizard

    Joined:
    Mar 16, 2009
    Location:
    The Jailbreak Community
    #5
    Sounds like a known Blackra1n issue. Is that what you used to JB ?
     
  6. KingHuds macrumors 6502

    Joined:
    Aug 2, 2008
    #6
    I did use blackra1n, but then I did a DFU restore and the problem is persisting. Maybe its a hardware issue as my sim works fine in my 3G phone.
     
  7. Vandam500 macrumors 68000

    Vandam500

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    Sep 29, 2008
  8. jbro1999 macrumors regular

    Joined:
    Nov 24, 2009
    #8
    This still isn't a sticky? I've had to look for this thread about 5 times now.
     
  9. -aggie- macrumors P6

    -aggie-

    Joined:
    Jun 19, 2009
    Location:
    Where bunnies are welcome.
    #9
    Subscribe to it and you won't have to look for it. The only way it could possibly be a sticky is if you reported it to the mods as needing to be a sticky. Whether they'll agree is up to them.
     
  10. scirica macrumors 68020

    scirica

    Joined:
    May 13, 2008
    Location:
    Dallas, TX
    #10
    Nice Job TheLatinist!! This should become a sticky soon...
     
  11. gixxerfool macrumors 6502a

    gixxerfool

    Joined:
    Jun 7, 2008
    #11
    Agreed. Sticky this. It's answered alot of my questions. Thanks to thelatinist.
     
  12. Joe G macrumors member

    Joined:
    Sep 27, 2009
    #12
    This is great info, thanks for posting it! I thought ALL 3GS needed a tethered jailbreak...now I see my 927 phone doesn't need to be tethered! Now I can update, jailbreak and get the best of all, Dragon Dictation, backgrounding, and tethering. Thanks for the post!
     
  13. mojoe24 macrumors regular

    Joined:
    Dec 1, 2009
    #13
    Yes, I have 359.3 I was worried at first since I got it at Black Friday.
     
  14. spencers macrumors 68020

    spencers

    Joined:
    Sep 20, 2004
    #14
    Thanks for the informative thread.

    Unfortunately I'm stuck with my brand new (bought today) 3GS, with iBoot-359.3.2, and serial XX946.

    What a let down. There is no way in hell that I would do a tethered jailbreak.

    UGH.
     
  15. dhlizard macrumors G4

    dhlizard

    Joined:
    Mar 16, 2009
    Location:
    The Jailbreak Community
    #15
    Sell it on Ebay or Craigslist and buy a gently used 3GS with old bootrom before the supply dries up.

    I bought 2 used but pristine 3GS phones to have untethered jailbreak.
     
  16. secretanchitman macrumors 6502

    secretanchitman

    Joined:
    Sep 13, 2007
    #16
    yeah i did. i know its a refurbed phone. i know, i know you dont have to tell me twice...
     
  17. spencers macrumors 68020

    spencers

    Joined:
    Sep 20, 2004
    #17
    Never thought of that... I'll have to consider it.
     
  18. actionsauce macrumors newbie

    Joined:
    Jan 21, 2010
    #19
    Im eagerly awaiting an update that says "SOLUTION FOUND!!"
     
  19. labman macrumors 604

    labman

    Joined:
    Jun 9, 2009
    Location:
    Mich near Detroit
    #20
    just a guess

    but I think your going to be waiting a while neither the dev-team or Geohot appear to be working on the solution at this time. I know geohot has said several times he has no interest.
     
  20. BergerFan macrumors 68020

    BergerFan

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    Mar 6, 2008
    Location:
    Mos Eisley
    #21
    Necessity is the mother of Invention.
    I'm sure if one of the Dev team's or Geohot's own personal 3GS' were tethered, then we'd be a lot closer to having a solution. :D
     
  21. thelatinist thread starter macrumors 603

    thelatinist

    Joined:
    Aug 15, 2009
    Location:
    Connecticut, USA
    #22
    Geohot has a IPT3 with the new bootrom, and has strongly implied that it is untethered. Geohot just has no desire to spend time creating a tool for the ingrates who bombard him with complaints and insults.
     
  22. actionsauce macrumors newbie

    Joined:
    Jan 21, 2010
    #23
    I searched for quite a while for the answer and I apologize in advance if this seems if this seems ignorant.

    Can removing cydia (through ssh) and uninstalling blackrain fix the tethering problem without a restore? That along with removing any of the other jailbreak components through ssh.

    I hope to unjailbreak my friends iphone but he backed it up after it was jailbroken so a restore would still be a tethered jailbreak. He would at least like to save all of his pictures and contacts. If anyone knows a way of doing this without putting it back to factory settings, youre help will be much appreciated.
     
  23. thelatinist thread starter macrumors 603

    thelatinist

    Joined:
    Aug 15, 2009
    Location:
    Connecticut, USA
    #24
    1) Contacts and pictures are synced with your computer, they are not backed up.

    2) Restoring from a backup will not re-jailbreak a restored phone. It may leave some traces of the jailbreak, but the phone will no longer be jailbroken.

    3) Doing what you describe through SSH will not unjailbreak a phone. Jailbreaking changes the file structure and permissions throughout the operating system, and cannot be undone through It needs to be undone by any means I know of short of a restore.
     
  24. Intell macrumors P6

    Intell

    Joined:
    Jan 24, 2010
    Location:
    Inside
    #25
    Removing Cydia and other jailbreak things via SSH will not remove the need to plug the iPhone into a computer to boot it. The most that will do is make the iPhone not boot at all. You will need to restore the iPhone through iTunes using the official Apple firmware.
     

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