Technology Insights

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

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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

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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 Errors

oclHashcat64.bin: /usr/lib64/libOpenCL.so: no version information available (required by ./oclHashcat64.bin)

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I have been working on a project using oclHashcat this afternoon and started to look into an error that has existed on a development server where we use oclHashcat for quite some time. After some digging around I am confident that regardless of the error existing there is not an issue but I wanted to post an article related to the error in case anyone else looked for a resolution to the error. Below is information on the libOpenCL.so error and my thoughts regarding the error.

Technology Insights

Overclock NVIDIA G210M & NVIDIA 9400G M GPU’s In A Dell Studio XPS 1340

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This weekend I was investigating the capabilities of the two NVIDIA graphics cards in my laptop and a password cracking application called oclHashcat. The oclHashcat application uses OpenCL, the Open Computing Language, to utilize the processing power of your graphics cards GPU’s to crack passwords. My laptop is a Dell Studio XPS 1340 which utilizes Hybrid SLI technology to offer a good amount of graphics power while using the least amount of battery life possible. The laptop accomplishes this by mostly using an NVIDIA graphics card, which is a NVIDIA 9400G M, that is installed on the motherboard and only calling the second graphics card, which is a NVIDIA G210M, when it needs to render something in say 3D or higher quality than the 9400G M is equipped to handle. One thing I happened upon during my research was an NVIDIA utility that will easily allow you to overclock your NVIDIA graphics cards which I describe in more detail below.

Information Security

OCLHashcat: Multi GPU Password Cracking on Linux using Open CL

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Recently some pretty major advances have come around in the world of GPU based hash cracking. Up untill now there was not much for Linux which would utilize multi GPUs to crack password hashs. This has been changed with the release of Oclhashcat. The release of oclhashcat signifies a signifigant jump in the speed on linux based GPU systems. There is also a cpu based version called hashcat but for this article I will be reviewing oclhashcat