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

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)