Use John The Ripper to crack password hashes

https://github.com/openwall/john

first unshadow your passwd and shadow files

../run/unshadow ~/tmp/passwd ~/tmp/shadow > ~/tmp/unshadow

export OMP_NUM_THREADS=8
john ~/tmp/unshadow

john --fork=8 ~/tmp/unshadow

john --show ~/tmp/unshadow

ubuntu dependencies

sudo apt install libopenmpi-dev openmpi-bin

centos dependencies / preparation:

yum install openmpi-devel openmpi openssl-devel 
module load mpi/openmpi-x86_64

get source and compile:

wget https://github.com/openwall/john/archive/1.9.0-Jumbo-1.tar.gz
tar xvf 1.9.0-Jumbo-1.tar.gz 
cd john-1.9.0-Jumbo-1/src
./configure --enable-mpi
make -s clean && make -sj4

now run it :)

mpirun -np 8 -host localhost,localhost,localhost,localhost,localhost,localhost,localhost,localhost ../run/john ~/tmp/unshadow

to check the progress run

kill -USR1 $(pidof mpirun)

download and install cuda if you haven't already

wget https://developer.download.nvidia.com/compute/cuda/11.2.0/local_installers/cuda_11.2.0_460.27.04_linux.run
sudo sh cuda_11.2.0_460.27.04_linux.run
wget https://github.com/openwall/john/archive/1.9.0-Jumbo-1.tar.gz
tar xvf 1.9.0-Jumbo-1.tar.gz 
cd john-1.9.0-Jumbo-1/src
./configure LDFLAGS=-L/usr/local/cuda/targets/x86_64-linux/lib CPPFLAGS=-I/usr/local/cuda/targets/x86_64-linux/include

the summary should show that OpenCL support is now enabled (yes)

make -s clean && make -sj4

now let's run it :) here is an example where I ran john the ripper on a server with 8x NVIDIA GeForce RTX 2080 Ti:

run/john --format=sha512crypt-opencl -dev=gpu -fork=8  ../root.unshadow

the –format option needs to be specified in order to use the GPU at all. without specifying a format, john will always default to the CPU implementation of the crypt algo. to figure out which format to use, start john without a format parameter and then look at the output to find the crypt that was used. now run

run/john --list=formats --format=opencl

to get a list of all crypts that support opencl. if you are lucky, the one you are looking for is in there as well :)

the -dev=gpu -fork=8 options are there to use all cards in parallel. this will fork 8 individual processes each working on their own range of passwords at a time and each on a different GPU. If you have multiple hosts with GPU you may use MPI for that.