New website created

A slight deviation from my normal weekly posts to announce that the most recent update to chewett.co.uk has been uploaded! I have added a couple of pages including: Contact me page – A simple page with the easiest way contacting me Legal Stuff – Includes the software licence for code snippets on my blog and website

Veracrypt Error device-mapper: reload ioctl Error Fixed

When trying to mount an encrypted drive using Veracrypt I encountered this error: chewett@bunker-master2:/mnt$ veracrypt /dev/sdc1 gen500 Enter password for /dev/sdc1: Enter PIM for /dev/sdc1: Enter keyfile [none]: Protect hidden volume (if any)? (y=Yes/n=No) [No]: Error: device-mapper: reload ioctl on veracrypt2_0 failed: No such file or directory I did some research and found out that

Overview of the Raspberry Pi Cluster

Now I have the power supply and built the stacking system I can show off the clusters initial state. Every Raspberry Pi in the cluster Here are the 7 initial Pi’s that are to become part of the cluster. Each have been given a codename to designate its position in the cluster. The Raspberry Pi designed “M” will be

Stacking Raspberry Pi’s

The stackable Raspberry Pi case purchased allows stacking Raspberry Pi B+ and Raspberry Pi 2/3 but I was planning to modify this to stack older Pi’s. Stacking the Raspberry Pi (256 MB) The original Raspberry Pi does not have any mounting points. This makes it quite hard to stack using my chosen stacking solution. Therefore for the time

Powering a Raspberry Pi Cluster

The Raspberry Pi doesn’t come with its own power supply so you need to decide how to power it. The recommendation from the Raspberry Pi website is that they have “found that purchasing a 2.5A power supply from a reputable retailer will provide you with ample power to run your Raspberry Pi”. After doing some research

Stacking multiple Raspberry Pi’s

For the Raspberry Pi cluster I wanted to make sure that they are neatly stored to keep them easy to reach. Why nicely storing them is important Each Raspberry Pi requires a power and network cable. When using a single raspberry pi the cables are not an issue but I am planning to use five as a baseline

Building a Raspberry Pi cluster

Today’s blog marks the official start of my Raspberry Pi cluster project. Here I will be documenting the process of assembling, building, and running a small cluster. This blog will include both code snippets,  hardware diagrams and the results of various projects using the cluster. Aims of the project The Raspberry Pi cluster will be looking into distributed

BIGINT Overflow Error Based SQL Injection

In MySQL 5.5+ you can abuse a new feature with BIGINT values. This involves a problem called integer rollover and your ability to run arbitrary SQL. The problem of integer rollover Integer rollover happens when a number is too big or small and is made bigger/smaller. In the case where the number is the highest

Why are PHP’s function names a mess?

I have always wondered this, its exceptionally hit and miss and there isnt any real standards. I recently found the reason on the internet Well, there were other factors in play there. htmlspecialchars was a very early function. Back when PHP had less than 100 functions and the function hashing mechanism was strlen(). In order to

Install Virtualbox guest additions on Fedora 21 XFCE

Installing via the normal route didn’t work and meant I couldn’t easily resize the screen. Doing the below allowed me to use the resize easily. Install rpmfusion on fedora run `sudo yum install akmod-VirtualBox VirtualBox-guest` run `cd /usr/src/akmods` run `sudo rpm -ivh VirtualBox-*.rpm` Once this was installed, rebooting will give you access to shared folders and fullscreen mode

Choose an open source licence

I was trying to find an open source licence that would fit my purpose for my Trend Analyser project. After some googling I found a wonderful website “Choose a Licence” This showed specifically what each main licence does and gave templates to use. It made it easier than reading through and trying to understand all

Selection/Click and drag doesnt work in Gmail – Opera

In opera normally click and drag or selection doesn’t work. This is because in opera Gmail serves up some CSS that breaks the display and stops you clicking and dragging text. To fix this, you can enable opera’s list of JavaScript changes, to make popular sites work. This is done by visiting: http://www.opera.com/docs/browserjs/

Add a user to a group in Linux

How to add a user to a group in Linux usermod -a -G Its a simple as that. So for me adding the user “chewett” to the user “vboxusers” i run the command usermod -a -G vboxusers chewett The -a flag means that the new group is appended, without it you will overwrite your current

Could not access network location \Hewlett-Packard\\

When trying to install MySQL Server it failed with the message “Could not access network location \Hewlett-Packard\\” After some searching it turns out this is a common issue where HP have inserted a registry entry with the install path of “\Hewlett-Packard\\” which isnt a valid location. This can be resolved by removing this entry. This

Location of GeoIP.dat for PHP

To find the location of GeoIP for PHP you can ssh into the server and use the “find” command. find / -iname GeoIP.dat Will return a list of file paths where the file with this name is found. In my case I found: /usr/share/GeoIP/GeoIP.dat /usr/local/share/GeoIP/GeoIP.dat /opt/geoip/share/GeoIP/GeoIP.dat In my case the bottom link was the one

Show trailing whitespace in Vim

Vim is a wonderful command line text editor with syntax highlighting and everything you could ask for provided you turn on the functionality. Recently i was shown that it was also show trailing whitespace with a quick addition to the .vimrc file. All you need to do is add the following: set list set listchars=tab:→\

Using Nvidia Optimus on Fedora

If your computer is recent and has an i3/i5/i7 intel core and a Nvidia graphics card it likely uses Optimus technology. This smart piece of software turns off the power-hungry Nvidia graphics card and runs most programs on the integrated intel graphics chip. In laptops this can save a lot of power. However this solution

Tile windows like Windows 7 on XFCE

Windows 7 has a really nice feature that lets you tile a window to the left or right of the screen, allowing easier placement. This is normally activated with the Windows-(left, right, up down) Arrow key combination. I had searched how to do this with XFCE for a while and today after upgrading to Fedora

XFCE Application Menu Icons Missing

After i installed Fedora 18 XFCE i found that it by default doesnt show the icons on the application menu. I normally navigate it by checking the images and not reading the words, so this inconvenienced me. On checking the properties I found that “Show icons in menu” was checked but it did not seem to

Raspberry Pi!

During Christmas I got a raspberry pi and I have been waiting to start playing around with it for ages. Finally I decided to order the remaining pieces for it such as the power cable and SD card. Since I didn’t have a HDMI TV around I decided to plug it into the router and

20 year old French hacker is arrested after stealing 500k euros and infecting 17k smartphones

A 20-year-old hacker has been recently arrested in Amiens, France after allegedly stealing 500k euros from unwitting victims. The hack worked by downloading and modifying android applications with a trojan which would call premium rate numbers in exchange for SMS codes  for playing online lotteries. Central Office for the Fight against Crime Linked to Information

Grace Hopper – Computer Science Legend

I’m relatively surprised that I hadn’t heard of her before a couple of weeks ago. While discussing small loop optimizations with some friends someone referenced her nanoseconds video (see below). This short video explains quite simply, the concept of a nanosecond. After seeing her talk about nanoseconds, I went to research her a bit further

A WordPress Site?

I eventually decided that i would start a blog that would document various things I do, if not for everyone, but myself. Numerous times over the past year I have felt I wanted to write long posts about certain topics that I meet, but haven’t had a medium to do so. The search for a