Ian P. Christian's Personal Blog Random witterings from pookey


How and why I cracked a password hash

I posted this originally 2 years ago, with references to the product and vendor. Unfortunately I got threatening legal letters, and almost lost my job! I've now stripped out the vendors references, and am putting it up simply because I think others will find my methodologies and write up interesting.

Some software I was working with stored its password using a custom written encoding method - and charge people for professional services who want to decode their passwords. Recently I wanted to migrate users from this system to an alternate one, so I had no choice but to reverse engineer the hash. I'm publishing this here to demonstrate why people shouldn't invent their own hash without fully understanding the consequences, and as an interesting example of crypto work.

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Installing VMWare’s ESXi guest tools on Ubuntu 11.10

There seems to be a lot of confusion in the IRC channel about how to install the guest tools on linux - with a lot of people recommending that you install the tools via the tools installer and the script. I really don't like to do things this way - as I believe things should be installed using the package manager, and creating .debs of the tools means you don't need to install a compiler on all of your guests.


Creating a custom form field type in symfony 2

I am finally starting to dive into symfony 2 properly. Yes - it's taken a while, work has taken me in different directions! I found myself needing to create a custom form field type pretty quickly, but couldn't find much in the way of documentation to do so, so I thought I'ld throw it up here; partly to help others, but mostly to get feedback to make sure I'm not approaching this from the wrong angle.


BeBook Live, an Android Tablet!

BeBook have announced the addition of a android tablet PC into their range of ebook readers. The new product is called the BeBook Live.

Here's a teaser video that BeBook have released, but check out the hands on review of the BeBook Live in the video lower down too.

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Customising the kickstart script for ESXi automated installs

After my last post, 'Installing VMware ESXi via PXE', I found that I needed to do a little customisation of the kickstart script on a per host basis. This post shows how I went about that, with a simple hack to aquire the MAC address and then customise the script based on that. This is a very simple example, but you could modify this easily for your needs. Notice I have two MACs per host below, this is because the machines could PXE over either of their 2 interfaces.


Installing VMWare ESXi via PXE

We're going down the route of virtualising our infrastructure at Timico, which means I'm having to get my hands dirty with VMWare. We've tried the Xen route, and not really got on with it - so it's time to move on to something a little more polished.

In this article, I'll outline how I plan on speeding up the provisioning of new tin to run as VM machines. The plan is to be able to plug in a new node whenever one is needed, and have it fully auto-provisioned from start to end. The first step in doing that is to automate the installation of vmware ESXi - which is done by PXE booting.

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Easier stalking with bitlbee and irssi

I wanted to find a way to make it easier to see when people came online with bitlbee and irssi. I already use a split screen with hilightwin.pl so that privmsgs and highlighted messages appear in a window at the top, so I wanted to find a way of using that

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Getting Real with GNS3 – connecting to physical networks

This short guide shows how you can connect emulated routers with physical routers using GNS3 and the Ethernet NIO. This is a cheap method for expanding your home networking lab, and it is amazingly simple. Whilst I'm using Windows, the same method will work with Linux too.


Configuring a Cisco 2509-RJ terminal server

I recently purchased myself a cisco 2509-RJ, which is similar to the 2509 / 2511, however rather than an octopus cable to connect to other devices, RJ45-RJ45 rollover cables are used. This article shows a full configuration example and details on the cables required. The configuration allows for reverse telneting into other devices.


IP Subnetting made easy

I've been asked to help people understand subetting a few times, so I thought I'd document it here to give me a place to point them to in future. Subnetting is explained in many places, with a large variety of methods. The key to working out valid subnets however is simply a matter of understanding the binary maths behind it. This guide explains a method to quickly do subnet maths, without any tricks. The guide will help you in calculating subnet boundaries and valid host address fast enough for use in a Cisco CCNA or ICND1 exam.