Like jailbreaking an iOS device, rooting your Android opens the door to many possibilities you otherwise wouldn’t be able to experience. If you fancy freeing your device from the shackles of stock, then please read the following tutorial how to Root Samsung Galaxy S II i9100 run Android 4.0.3.
Step 1: Download the required kernel for your Galaxy S II:
Base firmware I9100XWLP7 (UK, Eire): Download CF-Root v5.4 LP7
Base firmware I9100XWLP8 (Aus) Download CF-Root v5.4 LP7 (Works with LP8)
Step 2: Once downloaded, extract the .zip file. At this point, ensure your device is not connected to your computer.
Step 3: Locate Odin (should be included in the CF-Root package), and launch it by double-clicking on the .exe.
Step 4: Next, press and hold Volume Up + Volume Down buttons while connecting your device to your PC, until you see a Download Mode screen.
Step 5: ODIN will detect your device.
Step 6: Click on PDA and select CF-Root-SGS2_*-v5.3-CWM5.tar (file downloaded in Step 1).
Step 7: Click Start.