Technology Insights

JTR – John The Ripper Compile Error – /usr/bin/ld: cannot find -lOpenCL

The article below describes an error received while attempting to compile John The Ripper with GPU support via OpenCL on Ubuntu Linux version 12.04 LTS also known as Precise Pangolin. Many compile errors are related to necessary packages not being installed on Linux though other errors could be related to all sorts of different issues such as incorrect Library versions or files in the incorrect locations. In this case the specific error states that ld cannot locate the OpenCL library so below we describe the error in more detail, how to search to see if the proper libraries are installed, and the resolution by simply creating a symbolic link to the proper OpenCL library.

Technology Insights

JTR – John The Ripper Compile Error – common-opencl.h:8:19: fatal error: CL/cl.h: No such file or directory

Recently while attempting to get John The Ripper 1.7.9 jumbo-7 working on a Ubuntu 12.04 LTS Linux server with multiple AMD GPU cards in it I ran across an error during the compile process. The error complained about the VL/cl.h file not being installed and thus could not finishing compiling. Below I describe the compile error, how to locate the Ubuntu package that installs the necessary file to move past the previously mentioned compile error, and then how to install the correct package.

Technology Insights

JTR – John The Ripper Compile Error – sha.h:4:25: fatal error: openssl/sha.h: No such file or directory

Earlier while compiling JTR or John The Ripper password cracker on a new Ubuntu 12.04 LTS server I received a compile error. The error compiling JTR, which is noted in more detail below, pointed to the sha.h file not being found which likely means there is a missing package though I have seen other causes for file versions being incorrect. Below I explain the initial compile error in more detail, how to track down the package that provides the necessary file or files, and how to install the necessary package on Ubuntu.

Information Security

Calculate Disk Space Size Needed To Generate A Wordlist For Password Cracking

Today I was having a discussion regarding wordlist size, the calculation to come up with the specific size the wordlist would be once generated, and various other items revolving around password cracking. Somehow the application crunch came up which in the past has been used to generate wordlists however its fairly slow compared to other technologies out there specifically Hashcat/oclHashcat’s Anyhow during the discussion I was doing some searching and had not used crunch in quite a long time but was pleasantly surprised by one of the features which generates a quick, accurate, and useful output of information regarding number of combinations that will be generated from the combinations length plus the character set/wordlists input and how much disk space those the list will take up on the hard drive. Anyhow a couple interesting things I realized tonight using crunch that I wanted to share.