HOW TO: Jailbreak iOS 4.2.1 Untethered with Redsn0w 0.9.7b1 [Guide]
STEP 1: First of all, you have to jailbreak your iOS 4.2.1 device using Redsn0w by following the step by step instructions posted here.
STEP 2: Once jailbroken, tap on Cydia and check if your 4.2b3 SHSH blobs saved or not. You should see "SHSH: 4.2b3" in the status as shown in the screenshot below:
STEP 3: Now download Redsn0w 0.9.7b1 from the links given below and connect your iPhone, iPod touch or iPad.
STEP 4: Since this is a beta release, you must have usbmuxd that can be download from here. Now start terminal in python-client directory then type in the following commands:
chmod +x tcprelay.py
./tcprelay.py -t 22:2222
STEP 5: Now start Redsn0w 0.9.7b1 and point it to the official iOS 4.2.1 .IPSW file.
STEP 6: In the next page, check on Jailbreak Monte which untethers your iOS 4.2.1 jailbreak then point it to iOS 4.2 beta 3 firmware (Google it if you don't have a developer account).
STEP 7: Final step is to put your iOS device in DFU Mode using Redsn0w instructions on the screen.
Finally, sit back and let Redsn0w go in bunch of steps and you'll finally get untethered jailbreak on your new-generation iOS device.
Please note that this is a beta release, and upcoming versions will bring support for Windows users and will have built-in usbmuxd for easy process.
for more details go to HOW TO: Jailbreak iOS 4.2.1 Untethered with Redsn0w 0.9.7b1 [Guide] » Iphone Unlock Jailbreak Downloads Activate Hack Tools Application Games - Iphone Downloads For You