iREB is a specialized utility tool developed for the Windows operating system, historically used during the golden age of iOS jailbreaking. Specifically, version RC2 targeting iOS 4.0.x and 4.1 was a critical instrument designed to assist users in bypassing specific errors encountered while restoring custom firmware (IPSW files) via iTunes.
Review and Tutorial on how to get and use iREB and f0recast. iREB 4.0.x 4.1 RC2.zip 1
In this case, the ".zip 1" file likely indicates that the iREB tool has been split into multiple parts, possibly due to file size limitations or hosting constraints. The "1" likely denotes the first part of the archive, which, when extracted, will yield the complete iREB tool. Software Overview: iREB 4
These errors happened because iTunes would check if the device was in a "pwned" state before allowing a custom restore. If the device was in standard DFU mode, iTunes would reject the custom firmware and fail the restore. The Solution: iREB (iH8sn0w's Recovery Bypass) In this case, the "