Untethered Jailbreak for iOS 6.1.3 on iPhone 3GS

You can perform an untethered jailbreak on an iPhone 3GS running iOS 6.1.3 using a tool called p0sixspwn. This utility was specifically released to provide a permanent untethered solution for devices on this firmware version. To begin, download the p0sixspwn tool for your Mac or Windows computer. Connect your iPhone 3GS to the computer via USB and ensure it is recognized. Run the application and follow the on-screen instructions to start the jailbreak process. If you encounter issues with the standalone tool on newer operating systems, an alternative method is to perform a tethered jailbreak using Redsn0w first. Once the tethered jailbreak is complete and the device is booted, you can open Cydia and search for the p0sixspwn package. Installing this package from Cydia will convert your tethered jailbreak into a permanent untethered jailbreak. Always ensure you have backed up your data via iTunes before attempting these procedures.