Recently we have been doing a lot of testing of oclHashcat on CentOS Linux servers. The oclHashcat application takes advantage of the GPU’s, or Graphical Processing Units, of Nvidia graphics cards or ATI graphics cards. Anyhow one of the servers we have been testing with has four Nvidia 295 GTX’s and at times was receiving an error stating the kernel was disabling the IRQ. Below we describe the error in more detail along with a kernel parameter that was added to resolve the error. Even though we experienced this issue with oclHashcat specifically the error could happen with other applications and/or Linux Operating Systems so the resolution could be the same.
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.
I have been using Hashcat and oclHashcat a lot in recent weeks but have been limited to primarily using it on Linux servers so I decided to give it a shot on a couple Windows machines. Below I describe how I got oclHashcat operational on Windows 7 Ultimate 32-Bit on a desktop computer with a NVIDIA 9600GT GPU as well as operational on a Windows 7 Ultimate 64-Bit laptop with NVIDIA 9400G M GPU and a NVIDIA G210M GPU. Below is information on what needs to be done to get oclHashcat working on Windows 7.
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
If you have been following my progress over the last few days you will know that after a complete rebuild of the tools server and a change of the operating system, I have been working hard to get all our temp monitoring back online. The server previously ran Gentoo Linux, which although is still my favorite distro, is just not suited for a production server environment. So we decided to go with Cent OS which is a very well built distro aimed at running on production servers. My only complaint is that its kernel and some of its packages are a little bit out of date. On the bright side, this has given us a few challenges to work through and more importantly some good articles to share. So after getting my GPU temps going and graphing I turned my attention to the cpu. We are currently running a Intel i7 965 Extreme edition which I just put in last night. In the following article I will show how I eventually got lm_sensors and the coretemp module to work on Cent OS 5.4