The GreenPois0n untethered jailbreak for iOS 4.2.1 was released a few minutes ago and I already took it for a spin on my older iPhone 3G sporting iOS 4.2.1.

This step by step guide will show you how to use GreenPois0n to jailbreak your iPhone iOS 4.2.1. It’s worth noting that this version will not hacktivate your iPhone and that so far, there is only a Mac version…

Note: Steps to jailbreak the Verizon iPhone are exactly the same.

Step 1: Make sure your iPhone is on iOS 4.2.1 as GreenPois0n will not work with any other firmware.

Step 2: Download GreenPois0n from our iPhone downloads section.

Step 3: Plug your iPhone to your computer via the USB cable then launch GreenPois0n. Click on the “Jailbreak” button.

Step 4: As soon as you hit jailbreak, you will have to follow instructions for putting your iPhone into DFU mode:

  • Press and hold the sleep button for 3 seconds
  • Continue holding the sleep button while pressing the home button for 10 seconds
  • Release the sleep button while still holding the home button for 10 seconds

Step 5: Your device will now be ready for the jailbreak. Just wait a little bit while GreenPois0n works its magic.

Step 6: Once the jailbreak has been injected in your iPhone, you will see a new icon on your springboard for Loader. Launch Loader and install Cydia from there. Finally, reboot your iPhone and you should have Cydia installed

Step 7: Done!

Enjoy your newly untethered iPhone jailbreak for iOS 4.2.1.

  • vibe

    I can’t get greenpoison to recognize my 3g dfu mode, I know I’ve put it in dfu cause iTunes recognizes it. Just updated from 4.0.1 baseband is 05.15, I already had my 3G jb-en
    I activated and synced with a backup.

    Any suggestions?

    • mike

      did you get it going i had the same issue

      • asd

        HEY!.. I am having the same problem. My 3G won’t get into DFU mode following the instructions.. Did you guys get it working??..

      • asd

        HEY!.. I am having the same problem. My 3G won’t get into DFU mode following the instructions.. Did you guys get it working????..

  • zee

    I tried the greenpois0n and it didn’t work… 🙁 please help me

    • Try to check more sites that have step-by-step tutorial.

  • al

    Followed the tutorial and unlocked my iphone 3GS easy……..My question is after unlocking, it does not recognize my sim card…….does unlocking your iphone means you can use different sim card too? Any help, please.

    • Cipriana

      I´ve been asking this question for ages. Could someone please answer the questions?

    • abejoe

      U should do your homework 1st before attempting to do anything.
      http://www.iphonedownloadblog.com/2009/07/10/difference-jailbreaking-unlocking/

      • Cipriana

        Done all that. Homework or no homework, you just don´t get it. We aren´t all whizz hackers and jailbreak experts. We are just simple people trying to upgrade our phones. When you understand that then maybe we will all understand how to use this bloody software.

      • (Not at you abejoe) Sorry guys not trying to be rude or try to act all cool because I think I am a computer wizz…. but I am not, really I am not. The most complicated task I have done on a computer is changing the font and pictures in MYSPACE!….and 8 year old kids have myspace pages… even dead people and cats….but I do know how to use a freaking search engine, I swear technology is making people more stupid and more lazy, its not advancing us at all….it just does the work for us…..Any ways, I found a video of someone on YOUTUBE using a jailbreak and, the person did the entire jailbreak step by step, and broke it down barny style even… So, I downloaded the same program he used in his video(I also had the same firmware) and watched the video a second time while doing my jailbreak, its a jailbreak follow along… how special. and everything worked…. and by the way….. You know you dont HAVE TO USE GREENPOISON SINCE THERE ARE LIKE A THOUSAND JAILBREAKS OUT THERE, POISON WORKS FOR WINDOWS(used it on my friends iphone..on my computer, HP running windows 64bit, surely not a mac) AND IF!!!! IT IS ONLY FOR MAC THEN YOU ARE WASTING YOUR TIME COMPLAINING THAT ITS NOT THE RIGHT ONE FOR YOUR COMPUTER BUT STILL ASKING WHY IT WONT WORK…uh hmmm?!?!?!?! if you truely did do your “homework” then you would understand your software and programs…You can lie about your homework to your teacher, friends, and family….even me….. but you just proved that you didnt study very hard if you dont understand it,…I bet your dog ate the homework, because you got high, then you ate the dog, because you got high….in korea…

      • Cipriana

        Straight to you tylerrrr. First of all, try to find A SINGLE post of mine that says I tried this stuff and compain that it did not work. I DO NOT try anything until I am sure it works. And yes, you are trying to be rude or you would not put those retarded comments at the end of your posts. Wuss.

      • cipriana sorry i ment that to be sarcastic humor not sarcastic asshole. I was also talking about my first post when i said that i wasnt trying to act or sound smart. Also, I did offer to try and find a video or post for you, said i would try in the post before that one. all the videos i found were with different jailbreaks or models so not sure they will correspond with this one since i have not use this exact jailbreak my self but different greenpoison jailbreak that i got from piratebay. try to download another one from piratebay, it worked for me, but this one seems to be hit and miss as well…. cant tell you if your wrong, or the program or both since i cant see what you have and how your doimg it… so kinda hard to tell you how to fix it…

      • Cipriana

        All is forgotten and forgiven. I didn´t mean to offend either but it bothers me to see so many people lost with their iphones. Technology is supposed to make life easier not tougher. Ok, I did some research and found a tutorial with video and all updates, upgrades, software (including greenpoison and others for other versions, etc. The problem is also the iTunes upgrade. Most people want to upgrade iTunes and then re-jailbreak their phones. Some of these phones are also unlocked. iTunes 4.1.2 (or 4.1) + greenpoison + unlock DO NOT MIX, which is why people are having problems with their sim cards after jailbreaking with greenpoison. According to the blogs I´ve visited, you cannot upgrade to 4.1.2 and jailbreak on an unlocked phone. Some even say you should stay away from 4.1.2 altogether if you have an unlocked phone, which is my situation. I will have to live with my 3.2 OS until someone comes up with a jailbreak for 4.1.2 on an unlocked phone.

  • junior890731

    my phone is a 3gs, and i had jailbreak it before.
    and im thinking of upgrading to ios4 and jailbreak again.
    will jailbreaking the phone twice kill my phone?

    thanks

    • Odyssey1234

      You can jailbreak your phone as many time as you like

  • kevin

    mine start to restore to factory setting is that ment to happen

  • Jay

    my phone wont power on or anything after this, please help

    • Jacob

      Same here. When trying to go into DFU mode, the phone never turned back on. It will not power on anymore. Holding the power button, home button, or unplugging & re-plugging back into the computer. It bricked it?

      Anyone have any thoughts on this?

    • jake

      press and hold start and home it will come on

  • Jacob

    Anyway, I got it working again by just doing another reset. Hold power/sleep & Home button for 10 seconds.

  • Wes

    I did this on my iPhone 4 with 4.2.1 software and it worked for about 20 seconds.

    Then the iPhone re-booted, and started back up again but with NO PHONE, MESSAGES, MAIL, SAFARI, CALCULATOR ETC. ONLY HAD INSTALLED APS LEFT!! Downloading latest version (4.3) now to see if i can restore with iTunes! DO NOT USE THIS greenpoison PROGRAM WITH THE IPHONE 4.

    If anybody has any solution or has had a similar experience please reply!

    • Cipriana

      Maybe it´s because greenpoison is for Macs only? Could that be the reason?

      • Sascha

        Where did you get THAT?

        I ran greenpois0n on my Windows machine six weeks ago 😉

      • Cipriana

        Err, look at the original post!!!!

        Quote
        It’s worth noting that this version will not hacktivate your iPhone and that so far, there is only a Mac version…
        Unquote!!!

      • Marty

        Lol did you even look at greenposion site, there’s option to download Win version….
        geez dont troll here

  • Wes

    I REPEAT DO NOT USE THIS ON IPHONE 4 – ERASES ALL PHONE AND MESSAGE FUNCTIONALITY!

    I REPEAT DO NOT USE THIS ON IPHONE 4 – ERASES ALL PHONE AND MESSAGE FUNCTIONALITY!

    • Sascha

      No, it doesn’t erase anything.

      I did it with my iPhone-4 on iOS 4.2.1 without any problem.

    • Garrett

      Same here. I looked all around and thought that jailbreaking 4.2.1 (bb 3.10.01) wasn’t going to be possible until after 4.3 came out…….i had greenpois0n 6.1 just sitting on the backburner. I came across one blog that verified it worked, went ahead with it (just as GP instructs) and whammo! – the phone is Jailbroken! I ran through Cydia, got all the apps and settings that I’ve long been missing (BT mono headset for music, BT data xfer, BT mouse, even MyFi to make a tethering hotspot!).

      ….now I’m on the phone with AT&T as I’m typing this upgrading my plan to UNLIMITED DATA and UNLIMITED MESSAGING!

      ps. I didn’t lose a thing, I’ve even synced again through iTunes updating my music and non-Cydia apps/setting (which are untouched when you update).

      • Garrett

        … :(, turns out they don’t offer the unlimited data anymore.

      • farhood

        @Garret, what’s your iphone? 3G or 4? and did you got the unlock or just jailbrocken? mine has been already jailbrocken about 2 month ago but the problem is that probably there isn’t any unlock still. so carrier and network unavailable 🙁 without the unlock it’s good for nothing 🙁

      • Garrett

        @farhood: I have the iPhone 4 and I just jailbroke it (NOT UNLOCKED). All carriers are the same to me…I’ve never had service issues…it’s just expensive anywhere you go.

  • russell jones

    this doesnt work at all. remove it from your page, wasting peoples time.

  • Iluvva

    First Support the dev team, do not take your anger on ’em, if you are happy with out jailbreak set then be happy and use iTunes. This program is not responsible for your failure of achieving whatever you wanted.

    Second, this does work, more suggested for 3G 8GB users, will be more stable soon for rest of the version including 4 and 4G.

    • zee

      OK,,, I have an Iphone 3G, I tried installing it and it didn’t work. HMMMM!!!

  • togan

    Could I use this jailbreak program for iphone 4

    • Sascha

      yes

    • Yes you can use that jailbreak program for iPhone 4 running 4.2.1 iOS. It is easy to use. I have tried it.

  • WOW, some of you people really need to do your research!! Stop downloading jailbreaks and firmwares if your not sure what your using! GreenpoisON is one of the highest recommended jailbreaks for current iphones/pod/pad and firmwares except maybe 4.3,( that can’t be jailbroken if its the original apple firmware/kernnel without being rooted, downgrade, restore, and even then its difficult to go back to 4.2< after you upgrade 4.3). PLUS THERE ARE DIFFERENT GREENPOISON PROGRAMS FOR DIFFERENT COMPUTER O.S's(mac,windows), FIRMWARE TYPES, AND APPLE MODEL TYPES(3G,3GS,IPOD,IPOD) Just because you download greenpoisON for firmware 4.2, that doesnt mean it will work for iPHONE 4g, unless it says iphone 4g, 4.2, windows, mac ect… by the way, you cant use greenpoisOn without first having a restore firmware for both the program for its own Kernel, plus the restore since it wont work if YOUR PHONE IS ALREADY JAILBROKEN!!!!! plus greenpoisON is safer since it uses a firmware download to rewrite the kernnel for the jailbreak v.s using the iphone's original system…. its safer this way. The greenpoisON program is like this so if you, like many others dont research, just down load the first jailbreak you find, then ruin your iphone, but try to blame the software or company. With greenpoison's system you can copy your original firmware/kernnel and make it a registered restore so if you do screw up, you can restore your iphone and your retarded ass… hugs and kisses.

  • Cipriana

    Could you repeat that in simple English? Or maybe just simplify and tell us WHAT GREENPOISON CAN BE USED FOR (4.2, MAC, 3G). Jeez!

  • many websites should have the downlinks for the jailbreak you want that meets your software requirements, as in greenpoison: jailbreak for iphone 3gs firmware 4.2(win32)
    jailbreak for iphone 3gs firmware 4.2(win64)
    jailbreak for iphone 3gs firmware 4.2(mac)
    some have an auto detection that download the proper software for your computer to run it if it only says jailbreak for iphone 3gs 4.2, and does not specify the computer type.
    once you find the proper jailbreak for you device and current installled firmware(not the upgrade you want but what is on the device currently) download it to your desktop. If you are not sure how to use the jailbreak try to find a youtube video of some using the jailbreak you have, the firmware they use in the video doesnt matter, the jailbreak process is the same for all device types below firmware 4.3. just remember not all jailbreaks are the same. (i.e) greenpoison will be the same step by step for all iphone 3gs, but might be different for other model/devices. blkra1n will be a different step by step than greenpoison, but way blkra1n works will be the same for all iphone 3gs and firmware type. As in they all have the same ending(jailbreaks all use cydia) but how you get there to that ending is a different story. I will post somelinks in a few, just gotta try to find the most helpfull ones.

  • LeRoy

    my jailbreak says its done but after the screen goes white and the screen goes black with white text it only has 4 lines of words but on the video the whole screen is covered in text?? any idea why this is happening? and the iloader isnt there?? help please!

  • LeRoy

    i am also using greenpois0n rc6 for 4.1.2 could this be the problem??

  • LeRoy

    I meant 4.2.1

  • Jason

    I did my homework (I thought). And I started the jailbreak on my 3G (4.2.1) using Greenposi0n RC6. Got up to the point where the tutorial says “you will see a new icon on your springboard for Loader” And I have no idea what that means. What is my “springboard” Is on my phone or on my computer? If it’s on my phone, I don’t see anything now because my phone won’t turn on…HELP!

    • Erickarkos

      “sprigboard” is also known as your home screen with all your apps and stuff, correct me if i’m wrong

    • check your homescreen/springboard and a green icon or a blank icon is the loader.

  • Erickarkos

    works perfectly, had my iphone 3gs jailbroken withing about 5 minutes

  • John

    Ok I tried this with my phone and it doesnt work? I’ve tried at least 8 times. I have 4.2.1 on a 3GS and when I try it on my 2nd gen iPod with the same software it works perfectly the first time. I really need it for my phone and not my iPod. Any ideas why this is happening? Help please!

  • Thank you for giving info about jailbreak

  • Robert

    I’ve got a 3g now running 4.2.1. I’ve jail broken it (earlier ios, something in the 4.) before using one of the snows. I can’t get this green poison to work. It keeps missing the phones reboot, its not registering the fact. It fires up with the plug symbol but it only shows an itunes icon. either I’m missing something, or it has a insane exact timing requirement (which the snows didn’t) or it simply doesn’t work. I ran GreenPois0n RC6.1. Should I have ran GreenPois0n RC6 first?

  • Daniel R.

    Hey I have a iPhone 3G that I reset all settings and content on, so it’s locked down without an iPhone activated SIM card. I think the software is iOS 4.2.1, but I don’t know if this GreenPois0n jailbreak will allow me to get past the “Insert a SIM Card” screen. Do I need a ‘hacktivating’ jailbreak? What should I do?

  • Tyrone

    Fuck all y’all nigguhs!

    • hooked on phonics…. it can work for you too.

      • threefivefive

        lol, pwned 🙂

  • andy

    when i download the firmware and extract it on my widows i dont get the ipsw icon but lots of other files .then redsnow dont recognize the ipsw help

    • Bero

      Try downloading the file with firefox not IE

  • Mini

    I have an Iphone 3g on 4.2.1 and baseband 05.15.04 I have downloaded greanpois0n and am unable to get it into DFU mode no matter how many times i try. I follow the instructions to the letter. Is there something else i should be doing?

    • Travis

      I’m having the exact same problem

    • Bero

      Don’t download the file with Internet explorer try firefox.

  • Tony

    I’m on firm 4.1 and would like to updrade and JB to 4.2.1, will I lose all my apps and settings on this process?

    • Go on jailbreakme.com 4.1 or earlier it’s good don’t upgrade unless u have to

  • TwoForFivePounds

    If you stuck your finger up your a*s, do you think it will smell of poo?

    • Micky

      Yes it wil, and if your ass has been jailbroken it wil probably smell of semen and poo!!

    • Micky

      Yes it wil, and if your a*s has been jailbroken it wil probably smell of semen and poo!!

  • Willy

    I read on another forum (dutch) that the GreenPois0n is NOT for 3G.
    I didn’t work on mine, so started looking for the answer.
    Alternative is Snowbreeze or RedSnow.
    Didn.t have the time yet to test the Snowbreeze.
    And when your device has black screen, after putting it in DFU-mode, just push the homebutton and then the sleepbutton at the same time until you get the apple logo again, just wait, take a bit longer to reboot.
    Only thing that was gone: the internet pages that were saved in Safari.
    So good luck

  • sue

    im using iphone4 and green poison jailbreak too..using mac….but the problem is my app store,calender,contact all lost(mean icon not the history)……i thought it hide but it confirm lost…no more this original apps in iphone4…anyone got any solution? thanks:)

  • Thank you for giving info about jailbreak

  • Vincent

    Help, after using greepoison to jailbreak, i can’t manage to turn on my iphone.
    It hang at the rotton skeleton apple. Tried to restore with itune, but it can’t detect my iphone, as is not turn on. Please help to resolve.

  • I Have IPOD Touch 4G, 4.2.1 version.

    i want to put crack applications on it, which doesnot allow in original firmware.!!!!

    Please advise me. how to do that.

    many thanks.

  • hello

    Should I attempt the above TUTORIAL if I have the following Iphone:
    Iphone 3g (8gb)
    IOS 4.2.1
    Modem firmware: 05.15.04

    Will the above program (“GreenPois0n RC6.1: Mac – Windows”) do the job????

  • Greenpoison is the best jailbreak tool for untethred jailbreaking. It works in different OS. It is proven and tested that works on 4.2.1 iOS.

  • hello

    but does it work on any baseband??? or only particular baseband????
    b/c my one is Modem firmware 05.15.04.

    • Sobe

      I have a 3GS with the same firmware and was wondering the same thing too

  • Kool kid

    wow, “that was easy”

  • hello

    @ Kool kid
    can you or someone give me details of your iphone (eg 3gs, 3g…and baseband/modem firmware) if GreenPoison was successful in jailbreaking your phone….??????

  • cindy

    Ok just did it here are my steps

    3GS iPhone
    Baseband 05.15.04
    Version 4.2.1

    What I was go ahead and download greenpioson. Used latest version on site for windows.
    That takes u throughout step 1 and 2. Skip 3 for now
    Do 4 which is setting the dfu mode
    Then do 3 lauch the application click through and jailbreak. Took a good 10 minutes to do what it has to do.
    Once your phone restarts go find the icon called loader and click it to install
    Once that is done find the icon called cydia and install

    • hello

      but do you know if it works on an iphone 3G with the same settings as yours?
      And also is there an UNLOCK available for our Baseband + IOS version (without updating to baseband 6.15 – ipad’s baseband)?????

  • Crissmuss

    Works great with Iphone 4 ios 4.2.1 bb 03.10.01
    Thanks!

  • Hey If I have Updates My Iphone to 4.3.1 and wait to use this jailbreak can i go to 4.2.1? or do i have to wait for 4.3.1 on green poison?

    • hello

      you got to wait…when using any program to jailbreak your Iphone. You need to check if it matches exactly your:
      -IOS: that is 4.3.1 (in this case it does not)
      -Modem firmware
      -Iphone type (eg: 3g, 4, 3gs..)

      If any of the above 3 does not match the description then DO NOT USE IT or else you risk stuffing up your Iphone. Be warned.

  • jroy

    what does ‘Cannot locate packages’ mean when I’m trying to download something from cydia

  • iWanttoAsk

    hey i’m using iPhone 3G 4.2.1 firmware , do this tutorial will work for me smoothly ?
    or i have to JB with redsn0w ?
    Sorry for asking silly question
    Please answer

  • Tiowhatever

    Sorry for joining late in this discusson but I think it’s worth repeating,

    Willy said it all when he posted

    ” GreenPois0n is NOT for iphone 3G ”

    Just won’t work. You won’t get past the DFU mode.

    Try Sn0wbreeze or Redsn0w.

    • Ghost

      I have iphone 3g and it worked a treat……..

  • Lew

    Ok i downloaded Greenpoisen and im trying to unlock or jailbrake my iphone 3gs 4.2.1 and i duno where to download the jailbrake from.. nyhelp? its my first time trying this

  • Jo

    I just jailbreaked my iphone 4 4.2.1. But i don’t get up the Loader icon on my springboard. the program says that jailbreaking complete and its starts up but i cant see the Loader icon?
    Can someone please help me!!

  • Ghost

    Bunch of whinging pricks,
    I for one am not a computer whiz and i got it to work no problems.
    I have spent the last 4 hours trying to do something finally got this page and bang done.

    Now just to work out how to get my simcard network lock off so i can use any network…

    Any help would be appreciated.

    Chrz Ghost

  • lina

    great jailbreak and it’s simple!!..this is work for my iphone 3gs newbootroom,..thank you so much;)

  • dianne

    I can’t get pass the DFU.. is there something else i’m missing