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 Insights

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

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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

Crack Juniper Router Passwords, Juniper Password Hash Details

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Recently I needed to find out information about a Juniper router password which is stored as a hash in the router configuration. The tricky part is while the password hash is technically a MD5 hash it is modified to make it unique and make it harder to crack. Luckily there is a way to crack the hash using JTR (John The Ripper) though it will require that you also have the username associated to the password as the username is used as part of the salt for the hash. Below there is first information on how to crack Juniper hashes which are the same as Netscreen hashes followed by more information about the hash itself.