Setting up John the Ripper on GCP with OpenCL Guide

Creating the VM instance on GCP

Navigate to https://console.cloud.google.com and create a new instance with these following configurations:

disclaimer: I am only using this for a class assignment therefore only cracking some simple hashes, I am maxing out on everything even if I don't need them.

• Max CPU cores
• Max RAM
• At least 1 GPU
• Boot disk: "Intel® optimized Deep Learning Image: Base m19 (with Intel® MKL and CUDA 10.0)" This will have CUDA pre-configured.

Installing John the Ripper with OpenCL

clone https://https://github.com/magnumripper/JohnTheRipper , then make sure the GPU is "attached" (or available)

lsmod | grep nv

We should see the nvidia module here, to install opencl:

sudo apt install ocl-icd-opencl-dev

Now lets try if configurations of JtR is correct:

cd src
./configure

If there's an error: configure: error: JtR requires OpenSSL headers being installed, do

sudo apt install libssl-dev

Now we should be able to configure correctly:

./configure

Make sure:

OpenCL support ................................ yes

Now lets compile it with: (this is also mentioned in the very bottom of the ./configure log)

make -s clean && make -sj4

If everything is correct (if not then idk what to do, google?), cd to JohnTheRipper/run and do

./john --list=opencl-devices

to show the current configured GPU. And now if we run ./john --test it should show the result of using the configured GPU.

Happy hacking.