How to jailbreak 4.2.1 (tethered)

[DannyBoy]

The iPhone Dev Team has just released Redsn0w 0.9.6b4 today which brings first proper jailbreak, with working Cydia and MobileSubstrate for all iOS 4.2.1 devices.

For those of you who don’t know, Redsn0w 0.9.6b4 is based on Geohot’s Limera1n bootrom exploit which has already pwned all current iOS devices for life. The only problem is that it is a tethered jailbreak, which means you will have to boot it into a “jailbroken state” on every reboot. This so called tethered or semi-tethered jailbreak condition in Redsn0w 0.9.6b4 however only applies to the new devices like: iPhone 3GS (new bootrom), iPhone 4, iPad, iPod touch 2G (MC Model), iPod touch 3G and the iPod touch 4G. Old devices like iPhone 3GS (old bootrom), iPhone 3G and iPod touch 2G (Non-MC Model) can be jailbroken-untethered right now using this latest version of Redsn0w. So until and unless Comex of Spirit and JailbreakMe fame comes up with another untethered hack for iOS 4.2.1, the jailbreak we get for the newer devices will be tethered (or semi-tethered).

NOTE: Those of you who rely on a carrier unlock MUST STAY AWAY from Redsn0w and iOS 4.2.1.

Follow the step by step instructions posted below to jailbreak iOS 4.2.1 with Redsn0w 0.9.6b4:

Step 1: Download iOS 4.2.1 for your version of iOS device.

Step 2: Update/Restore to iOS 4.2.1 firmware using the IPSW file you just downloaded via iTunes 10.1.

Step 3: Start Redsn0w 0.9.6b4 and point it to iOS 4.2.1 firmware to proceed with the jailbreak.

Step 4: Now select “Install Cydia” and click “Next”. Optionally (if available), you can also select any other option you like.

Step 5: Now make sure your device is both OFF and PLUGGED IN to the computer before you click “Next”.

At this stage you will be presented with a screen where you will have to quickly hold “Power” button and then while holding the “Power” button, you will now have to hold “Home” button too. Now after few seconds release “Power” button but keep holding “Home” button until installation begins.

Step 6: Sit back and enjoy while redsn0w will do all the rest for you. Once done, your iPhone or iPod touch will restart automatically and you will find it jailbroken on the latest iOS 4.2.1 firmware.

For iPhone 4, 3GS (New Bootrom), iPod touch 4G / 3G / 2G, iPad ONLY:

Step 7: Now from here onwards, whenever you want to do anything related to jailbreak like SSHing into your device, or running Cydia, you must first run your device in the so called “jailbroken state” on every reboot by using “Just boot tethered right now” option in Redsn0w.

Redsnow-Windows-Link

Redsnow-Mac-Link

 

[JTSVMktg]

Is it really worth it to update? If I just got my phone running smooth while being JB'kd and as a power user am I gaining anything by being updated other than the apps I've tried to to install today that are for 4.2 update?

My first thought is too wait however my curiosity says update.

What is your opinion also am I correct in recalling that you don't JB?

 

[Gregoris]

excellent news, and tethered is ok because how often do you restart the iphone any way?

 

[Bobik]

who cares about the jailbreak anyway. WE need UNLOCKY

 

[DannyBoy]

Is it really worth it to update? If I just got my phone running smooth while being JB'kd and as a power user am I gaining anything by being updated other than the apps I've tried to to install today that are for 4.2 update?

My first thought is too wait however my curiosity says update.

What is your opinion also am I correct in recalling that you don't JB?

Mine isn't at the moment. I'm going to wait and see what other tools come out before I jump. Lately, I have just jailbroken for MiWi. But if you just got an iPhone and want a jailbreak this is the way to go for now.

 

[Gregoris]

who cares about the jailbreak anyway. WE need UNLOCKY

who cares about unlock we dont need unlock we have sim free iphones or are happy with the carrier its locked to

but with out jailbreak you have no unlock any way so the jb is just as important for you to have.

 

[Bobik]

who cares about the jailbreak anyway. WE need UNLOCKY

who cares about unlock we dont need unlock we have sim free iphones or are happy with the carrier its locked to

but with out jailbreak you have no unlock any way so the jb is just as important for you to have.

True, but I bet $1, that there are more people who need UNLOCKY more then who need jailbreak.

 

[Gregoris]

who cares about the jailbreak anyway. WE need UNLOCKY

who cares about unlock we dont need unlock we have sim free iphones or are happy with the carrier its locked to

but with out jailbreak you have no unlock any way so the jb is just as important for you to have.

True, but I bet $1, that there are more people who need UNLOCKY more then who need jailbreak.

your probably right, the amount of countries still have iphones locked to a single carrier...

though i updated about a week ago i was using the 4.2 gm and then the 4.2.1 so i dont need jailbreak and am happy to go with out it.

+ with out jailbreak how will you unlock? remind me where is it you find your unlock tool? lol

 

[Gregoris]

@MuscleNerd
MuscleNerd
@hiemanshu now that redsn0w is out, can focus back on the unlock. The 3G/3GS version should be out this week. i4 will be longer.

Twitter

 

[skweekymagee]

excellent news, and tethered is ok because how often do you restart the iphone any way?

I personally think tethered Sucks. You never know when you might download something from Cydia where the phone needs to be rebooted. If that happened then you could be stuck.

I'm interested in the process that's in the works how to make it untethered using your saved 4.1 shsh blobs but not so I can update to 4.2.1 but maybe for something futher out. Right now 4.2 offers absolutely nothing for me.

 

[Gregoris]

excellent news, and tethered is ok because how often do you restart the iphone any way?

I personally think tethered Sucks. You never know when you might download something from Cydia where the phone needs to be rebooted. If that happened then you could be stuck.

I'm interested in the process that's in the works how to make it untethered using your saved 4.1 shsh blobs but not so I can update to 4.2.1 but maybe for something futher out. Right now 4.2 offers absolutely nothing for me.

personally ill update even if the firmware has nothing to offer like the other one that was only to stop jailbreakme.com

but 4.2.1 has mobileME's find my iphone for free, to me thats reason enough to upgrade new sms tones and printing that ill never use but its nice to have there just in case..

i agree with you though un tethered would be better

 

[iGaz]

So what happens when you have to reboot? I know you will have to plug it in to your computer and then jailbreak again but, are you left with a restored phone and have to start again or are you right back where you left off...?

 

[N4N113]

so is a un tethered version coming?

 

[Gregoris]

the first few files from cydia i know i reboot 100 times, so that would b annoying

 

[umarrehman187]

how do i get the ipsw 4.2.1 file?

my ipad is already updated to 4.2 firmware?