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.