Jailbreak iOS 5.1 on iPhone 4 with RedSn0w for Mac [Guide]

Here are instructions on how to do a tethered jailbreak on your iPhone 4 running on latest iOS version 5.1.

If you follow this guide, you will upgrade the baseband version on your iPhone 4. This could be a big problem if you want later on to carrier unlock your iPhone 4. If you need a carrier unlock you should upgrade your device to firmware 5.1 only with a custom firmware which will prevent the baseband firmware from upgrading. Please note: this jailbreak is the tethered version only, so you’ll have to reboot with your Mac whenever you turn your device off, or reboot it for any reason. It is a slight inconvenience, yet if you really want a jailbreak, you will have to use this solution as it is the only possible one at the time being. Further, you should really save the SHSH blobs before you continue. You can find the instructions on how to do this in our blogs archives.

Step by step instructions:

1. Make a new folder (on your computer) and name it RedSn0w
Now download the RedSn0 jailbreak tool from here and save it to your new folder called RedSn0w you just made. Next you need to fetch the ipsw file which can be found here. Save it into the RedSn0w folder as well. This is necessary only if you are upgrading to iOS 5.1. Obviously if your iPhone is already upgraded to this iOS you can skip downloading the iOS 5.1 ipsw file altogether.
Click on the RedSn0w file to unzip (extract) it.

2. Only for those who need to upgrade to iOS 5.1.
Connect the iPhone 4 to your Mac and launch iTunes.

Select your iPhone from the list. Press the Option on your keyboard and select Restore (in iTunes).

Now browse to the RedSn0w folder and choose the ipsw file you have downloaded in first step.

The device will upgrade its firmware.

3. Start the RedSn0w software.

4. Choose the Jailbreak option.

5. Again, plug your iPhone 4 into your Mac turn it off and choose Next option.

6. Follow the on-screen instructions which will help you to get your iphone into the DFU mode (DFU stands for Device Firmware Upgrade).

Press the Home and Power buttons on the device for at least 10 seconds.

Now release the Power but keep your finger on the Home until RedSn0w discovers your iPhone.

7. Your iPhone 4 will reboot itself.

8. RedSn0w will now work on the jailbreak data.

9. Choose Cydia option and then Next.

10. Your device will reboot once more. RedSn0w will upload the RAM Disk.

11. When this part is done, you will see a notification which says that RedSn0w has finished. Wait until your iPhone reboots which will take a couple of minutes. Your iPhone is now jailbroken and you will see the Cydia icon on your iPhone.

How to boot tethered:

When your device is jailbroken you will need to boot the device up into the jailbreak state. To do this, start RedSn0w and choose the button Extras.

Select Just boot from the Extras menu to just boot tethered.
Now select Just Boot button in the RedSn0w menu. Your iPhone 4 is now jailbroken and ready for use!

Related Posts:

• iPad 3 jailbroken three times on the release day
• Jailbreakers working on jailbreak for iOS 5.1
• Apple stops signing iOS 5.0.1 firmware
• Dev Team upgrades RedSn0w, iOS 5.1 now supported
• Utrasn0w 1.2.5 carrier unlock updated, minor bugs removed