John the Ripper, also know as john in yum & apt package managers, is an open source password cracker and hash decipher program.
Here is a “How To” tutorial for using John the Ripper on VPS or Dedicated instances so that you can leave it running overnight, for example.
John the Ripper CentOS & Fedora installation & usage:
# john requires openssl-devel package
yum install openssl openssl-devel -y
# get the latest JUMBO version of John
# extract and enter the src folder
tar -xzvf john*
# configure and make john
./configure && make
# navigate and run the test and benchmark script