iREB is a Windows-based GUI application designed to put your iOS device into a "Pwned DFU" state. In standard DFU mode, iTunes checks for official Apple signatures before allowing a restore. By using iREB, you "pwn" the device’s bootloader, allowing it to accept custom firmware created by tools like Sn0wbreeze or PwnageTool.
The 4.0.x / 4.1 RC2 release was particularly significant because it introduced stable support for iOS 4.1, a popular version for legacy iPhone and iPod touch models. iREB 4.0.x 4.1 RC2.zip 1
The 4.1 RC2 version expanded compatibility to a wide range of "Limera1n-compatible" and older devices: 2G, 3G, 3GS (Old & New BootROM), and iPhone 4. iPod Touch: 1G, 2G (MB & MC), 3G, and 4G. iPad: Original iPad (1st Gen). Apple TV: Apple TV 2. Step-by-Step Tutorial: Using iREB 4.1 RC2 iREB is a Windows-based GUI application designed to
Typically caused when a custom IPSW is restored over a non-pwned DFU state. iPad: Original iPad (1st Gen)