How to Find IPSW for Redsn0w 4.2.1 (3 Steps)

Download the appropriate 4.2.1 IPSW firmware file to your computer by clicking on Apple's link to the firmware file. Apple released three versions of this IPSW firmware file based on the type of iOS device you want to use with the firmware file.
Double-click the Redsn0w icon on your computer to launch the Redsn0w jailbreaking tool.
Select the iOS 4.2.1 IPSW firmware file you download to your computer when prompted to select the appropriate iOS 4.21. IPSW firmware file.
VPS Hosting