It is a question I hear a lot. First, why do you need DFU mode? DFU means download firmware update and and you need this to recover your iPhone or iPod touch.
In adding up to the recovery modeon the iPhone, iPod and iPhone, iDevices based IOS has another form called DFU mode. The major difference between the recovery mode and DFU mode is whether iBoot boot loader to load or is bypassed during start-up, an agent with iBoot, when available, ensures that the user can not flash the firmware or the system operating less version prior to existing downgrade.
DFU mode or iphone recovery mode bypasses the iBoot load while maintaining the iTunes interface, allowing greater or lesser IOS. Ipsw to be flashed and restored in the device, including IOS firmware flash a custom-built or homemade. DFU mode is mainly used by hackers to downgrade or upgrade firmware with PwnageTool jailbreak pre-created. DFU mode, the screen is totally black without displaying the text, as when the phone is in power state.
The following is a little guidance on how to enter DFU mode on your iPhone or iPod Touch. It works on the iPhone 3G iPod Touch 4 2G and 3G 2nd 3rd 4th First Generation or Generation. At the same time it also worked for the iPad.
-Hold power, or sleep-wake and home affairs, the buttons simultaneously for 10 seconds. Power button or sleep-wake button and continue holding the Home button for another 10-60 seconds.
– Wait until iTunes recognizes and acknowledges iDevice DFU recovery mode, a notification message or a sound system to show the hardware on or off.
-The device is now in DFU mode.
Recovery mode, which is the standard way to update or restore the default iDevices, iBoot used when you restore or upgrade your iPhone to make sure that the IOS. By ipsw version number is greater than or equal to the current one is flashed from or written to the device, or otherwise does not allow the restoration process to proceed. In addition, if the iPhone, iPod touch is jailbroken or pwned custom-built OS firmware cannot be flashed. If the device is not connected to the computer in recovery mode, the screen displays “Please Connect to iTunes” logo.