Redsnow is easy to use, it is available for Windows and Mac OS. Pwnagetool can be used to create custom ipsw and preserve baseband, it supports Mac OS only.
Ultrasn0w doesn’t work on iOS 4.3.1 yet (even with iOS 4.3.1 + old baseband). The fix will be available soon. Here’s a warning from DevTeam for unlockers:
Good news everyone. DevTeam recently posted a tweet where they inform us that they will soon release a new version of Redsn0w utility for Windows. It will be an untethered jailbreak for iOS 4.2.1 using the Monte iOS 4.1 technique.
In fact, Apple still provides 4.1 ipsw and this could be used to jailbreak.
In addition, the team warns that Windows version will be very slow because the program uses the filesystem instead of RAM.
The iPhone Dev team has just released the second beta of their untethered RedSn0w jailbreak (the first beta has been released few hours ago and has more bugs).
New jailbreak is called “Jailbreak Monte”, as it uses new “backup method”. The iPhone Dev Team warns that their beta-version is not a general release and you should back up all your media before using it. There are also other limitations and bugs:
The beta is limited to iPod touch 4G, iPad and iPhone4;
The team asks not to participate in testing if you rely on the ultrasn0w carrier unlock;
The bluetooth functionality is disabled due to sandbox problem;
iPod player works only on iPod touch 4G;
To use this version of jailbreak Cydia should have your 4.2b3 SHSH blobs saved on file and following:
“You must already have the usbmuxd software installed and running on your Mac (this requirement will eventually go away too). The correct invocation of the relay is just as that page says: “./tcprelay.py -t 22:2222”. If the relay isn’t installed or running correctly by the time the redsn0w ramdisk has started, you’ll need to restore to stock FW again to try it again. Please test it beforehand to save yourself some time!”
Now, if you’re ready to apply this version of jailbreak, upi can download redsn0w 0.9.7 beta here.
After downloading and applying just select “Jailbreak Monte” to try out the untether.
The iPhone Dev team asks to test it after a fresh restore in order to keep track of the variables involved. Be careful!
By the way, iPodUplink has posted a video where you can see how to jailbreak your device with the latest version of redsn0w:
Jailbreak utility RedSn0w 0.9.6 b5 is available for both Windows and Mac OS X. The process is the same on both operating systems. So you can use redsn0w tutorial for windows. There is only one major difference – download redsn0w for Mac OS hereor here.
If you have an iPhone 3GS with the new bootrom you will only be able to perform a tethered jailbreak at this time. This means you will need Redsn0w’s assistance to boot into your jailbroken device.
IMPORTANT FOR UNLOCKERS
During this process you can update your baseband to the 06.15 version. If you are on 05.14 or 05.15 or higher you will need to do this to unlock. You do not need to do this for jailbreak only. Please read the following very carefully before deciding whether to do this.
There is no way to come back down from baseband 06.15, and there’s no hiding the baseband version from Apple. You’ll be voiding your warranty in a very obvious way.
If some future baseband comes out with a critical fix, you won’t be able to update to it if it remains down in the 05.xx sequence (then again, you wouldn’t update to it if you wanted to keep your unlock anyway).
Starting with FW 4.2.1 if you have 06.15 on your iPhone you won’t ever be able to restore to stock firmware (it will fail). You’ll need to only restore to custom IPSWs (then again, if you’re unlocker you should already be doing that).
Don’t update to 06.15 if you don’t need to, you can just jailbreak without unlocking using this tutorial! Only update baseband if you need the unlock and you’re stuck on baseband version 05.14 or 05.15, and you’re willing to assume the above risks. You can find out your baseband version in Settings -> General -> About -> Modem Firmware.
Those with an unlockable baseband and on a lower firmware should use PwnageTool instead to update without upgrading your baseband.
Step One
Create a folder on your desktop called Pwnage
Download RedSn0w from here or here. Save it in the Pwnage folder. Likewise, download the latest 4.2.1 firmware from below and place it in the same folder.