You are responsible for everything that you do to your device. If you do any mistakes or mess something up it's your own fault. DO NOT BLAME ME or ANYONE ELSE.
I, Daily Mobile, iPhone Dev-Team, nor anyone else takes any responsibility to any harm done to your equipment. You do this on your own risk.
THIS TOOL IS TO BE USED AT YOUR OWN RISK, IF YOU DO NOT KNOW WHAT THIS IS,
PLEASE STOP USING THE APPLICATION AND DELETE IT.
I have NOT done this. I am sharing a guide composed from other guides.
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This is a guide for how to use this software. You should check that your version of iOS is jailbreakable. Always use the latest version of redsn0w if you're not prompted to do otherwise.
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redsn0w
DOES NOT preserve your baseband.
If you rely on ultrasn0w
DO NOT USE redsn0w. Use
Pwnage Tool if you want to preserve your old baseband (01.59.00, 04.26.08, 05.11.07, 05.12.01, 05.13.04 or 06.15.00) and be able to
continue to unlock your phone.
If you have a newer, nonunlockable baseband, you're out of luck. Sorry, there is NO WAY for you to downgrade it.
You neediPhone
Mac running MacOS x 10.5 (Leopard) or later
Data cable connected to an USB-port
on your computer do NOT use a hub in you keyboard, monitor or dedicated hub
iTunes
Download redsn0w from
http://www.redsn0w.us/2010/03/download-direct-links-jailbreak-guides.html. I'm running it from the ZIP, extract it if you want to be on the safe side
Download the IPSW for your device from
http://getios.com/Let's get started0. Skip to step
4 if you're already running the software version you which to jailbreak.
1. Connect your iDevice and open iTunes (if it doesn't do it on connect)
2. Select your iDevice from the left sidebar and now SHIFT-click on Restore

I don't have a screen shot from my Mac, but it looks pretty much the same
3. Select the IPSW you've downloaded in the pre-steps and let it start restoring
Get a Club Soda and some cake, relax and let iTunes do it's thing
When it asks either restore an old backup or even better make it a new device and enjoy a faster device
4. Open redsn0w.
5. Click on Browse

6. Select your IPSW-file and hit Open

Let it check the file
7. Click next when it has successfully identified the file

8. Now check the options you want. You should check Cydia to continue, the multitasking gestures is nice if you want to increase the lifespan of your poor home-button. Click Next

9. Now follow the on-screen instructions.
Plug the iDevice in to your computer (if you haven't yet), and only then power it off.

They are as follows:
1. Hold the power button for 3 seconds
2. Keep holding the power button and now also press down the home button for 10 seconds
3. Release the power button, but keep the home button pressed fro 15 more seconds
You're now in DFU-mode and redsn0w will start the jailbreaking automatically. When it's done it will reboot.
When the process start, grab yourself another Club Soda.
When it's done, enjoy the freedom of a jailbreaked iDevice!
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You are responsible for everything that you do to your device. If you do any mistakes or mess something up it's your own fault. DO NOT BLAME ME or ANYONE ELSE.
I, Daily Mobile, iH8sn0w, nor anyone else takes any responsibility to any harm done to your equipment. You do this on your own risk.
THIS TOOL IS TO BE USED AT YOUR OWN RISK, IF YOU DO NOT KNOW WHAT THIS IS,
PLEASE STOP USING THE APPLICATION AND DELETE IT.