Teenager repellant technology turned to their advantage

Like it is said, every tool can be used either for the good or for the bad.  Because of a medical condition called presbycusis, an age-related loss of hearing.  People above age 20 loses their sensitivity to high frequencies 18 to 20Khz.  This means that only teenagers would be able to hear sounds / noises in such frequency band. 

Based on this technology, security company, compoundsecurity, has developed a device to prevent / repel teenagers from anti-social gathering infront of stores.  This device emits an ultrasonic sound / noise only audible to teenagers.  Here is the video (in french) of the device in action.

Ironically, the same medical condition, used in a different context, is turning to the advantage of the teenagers.  Some teenagers in UK has recorded this ultrasonic sound on to their handphone so that they can receive calls and sms during class without their teacher knowing about it.

This is a clear example of how, technology, used differently can be to one’s advantage as well as one’s disadvantage.
Reference: textually.org, ringtone

Useful command in windows command shell

Here is a list of commands that might be useful in a windows environment:

• color (changes the color of the command shell) e.g. color bf
• date (displays or set system date) e.g. date /T 
• time (displays of set the system time) e.g. time /T
• echo (echoes the variable) e.g. echo %PATH%
• set (displays / sets an environment variable) e.g. set path, set /P PATH=c:\ 
• start (starts another shell) e.g. start
• assoc (displays / associates a file extension to a file type) e.g. assoc .pl
  
• ftype (displays / associates a file type to a program for execution) e.g. ftype perl
• subst (associates a folder to a drive letter) e.g. subst z: myfolfer

The more usual commands such as more, cd, rd, rem, move etc. are not mentioned above so as to keep the list consise.

Network commands
Some common networking commands that can be issued:

• ipconfig (displays the configuration of your ethernet ports)
• ping (test connectivity)
• tracert (trace the hops taken from your host to a destination host)
• pathping (a combination of ping and tracert)
• netstat (displays active tcp connections and ports on which the computer is listening)
• nslookup (lookup an fqdn into an ip)

I hope some of these will come in handy to anyone out there
References: command windows

Why companies release software with bugs

Came accross this article at Gurardian.co.uk, written by Eric Sink, founder of SourceGear.
For every bug fixed, there are new bugs being introduced into the software.  Every change is a risky change.  The bug that is being introduced might be worse than the bug being fixed or it might be not as bad as the previous bug.  So how do one know which bug needs to be fixed and when?
Eric suggest to consider the following factor:

• How bad is its impact? (Severity)

• How often does it happen? (Frequency)

• How much effort is required to fix it? (Cost)

• What is the risk of fixing it? (Risk)

An example cited from the article is when many potential customers asked to support Oracle besides SQL Server.

• Severity: Losing potential customers
• Frequency: None
• Cost: Very high since the original code was tailor-made for SQL Server
• Risk: Changing big portions of the code will surely introduce a lot of bugs.

So, sometimes, software just had to be delivered with some known but acceptable bugs.
Note: Although the example given is not about a bug but rather a feature of the system, but we get the point.
Reference: Guardian, Original article: Code Economist

Browsing Reconstruction

We are all weary about people who invades our privacy, mostly when it comes to our browsing habits. Most people using IE just clears the cookies, temporary internet files and the browsing history under Tools -> Internet Options. But does that really clears off everything. Answer is NO. It does not.

Welcome to Index.dat
IE maintains index.dat files for your temporary internet files, cookies and browser history. The location are as below:

• \Documents and Settings\\Local Settings\Temporary Internet Files\Content.IE5\
• \Documents and Settings\\Cookies\
• \Document and Settings\\Local Settings\History\History.IE5\

Index.dat is a binary (non-human readable) file. These files indexes your temp inet files and cookies to the urls you visited. The format is proprietary to Msoft, but there are some tools out there that can help you parse it and put it in human readable form. The best open source tool in the market is pasco which is developed by Keith Jones, author of Real Digital Forensics.  In this blog, we will take a closer look at format of index.dat and how to use the successor of pasco, Web Historian.

Index.dat: Header
The header consists of the following:

• First 27 bytes: Client UrlCache MMF Ver 5.2
• 28th byte: 0×00 (NULL terminated string)
• 29-32th byte is the file size ( you need to convert it to little endian)
• 32-36th byte is the offset for the HASH table (more on that later)
• directory listing of all the directories containing the temp inet files. Offset 0×50. 12 bytes in size

As an example, look at the picture below:

The first 28 bytes is the null terminated string Client UrlCache MMF Ver 5.2
The next four bytes is the hex string 00C0 0100, which when converted to little endian gives 0001 C000 equivalent to 114688 bytes.
The next four is the offset to the hash table which is 0050 000 which gives 0×5000

The comes the directory names: N2L6K2BN, 0PE341MV, CD1JKLMN, S9MJSH6B

Index.dat: Hash table
to be continued…

References: Whitepaper from Keith jones,

Kixtart – a newbie perspective

Recently i discovered that where i’m working, the administrators runs a software and hardware asset management script every time i log in to my system.  Upon logon, i could see a folder being created under C:\sam containing a few files:

• SAMHW.exe
• Kixtart.exe
• samv3.kix
• and other dll files

After some investigation i managed to find out that

1. SAMHW.exe is a hardware asset management tool.  It will scan your PC for new or suspicious hardware
2. Kixtart is an executable that is run upon logon but before the desktop is launched.  This means that it is the first thing that runs on your PC whenever you log on to your domain.  You cannot stop it from running else you will be log out of your system due to the BREAK command.
3. samv3.kix is the a software auditing script that is run by Kixtart.exe

What the script usually does is to scan your registry for new / suspicious / pirated softwares, and log those in a file stored in a shared / networked directory name after your machine id / user name / computer name.

How to stop it from running? You can’t.  By design kixtart cannot be stopped from running the moment you log on to your domain. 

So what can you do?

1. Delete the folder c:\sam
2. Before bootup, remove all network connections from your laptop
3. Bootup up and log in as per normal
4. If you need to access domain folders etc, you should still be able to access since your IP address will reflect that you are eligible to access
5. Remove network connections before you log off.

Reference: www.kixtart.org, ars technica forum

How to surf securely in a wifi hotspot

We all know that our wifi packets can be easily sniffed by people, thereby making our surfing not private. So how do we surf in privacy without much hassle in a wifi hotspot. Easy. First you need:

1. A server where openssh is running
2. putty
3. Firefox

Step 1: Configure putty for an ssh session to your server
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Step 2: Configure a secure tunnel
a. Click tunnels
b. Under “Add new forwarded port” type 7070 (or any port number)
c. Click Add Button
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Step 3: Connect to your remote host
Just double click your connection profile

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Step 4: Confifure firefox to use your proxy

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Step 5: Ensure that your DNS request also goes through your proxy
In firefox open the about:config page
Change network.proxy.socks_remote_dns to true

On a linux host you could to the following: ssh -qTfnN -D 7070 remotehost instead of using putty. Thanks to thinkhole for this great article

Fixing Window’s XP with eight commands

I have come accross a great article which describes how to fix boot problems with windows XP. I am sure many of us have gotten into problems such as Windows NT could not start because the below file is missing or corrupt:X:\WINNT\System32\Ntoskrnl.exeWell, no more re-installing Windows XP. Just follow the steps below:
1. Insert your start-up windows XP cd
2. Select 2 to go to your recovery console (usually the prompt will be C:\WINDOWS)
3. Type

• cd .. ( go to prev directory – C:\)
• attrib -H c:\boot.ini (Remove the hidden attribute)
• attrib -S c:\boot.ini (Remove the system attribute)
• attrib -R c:\boot.ini (Remove the read-only attribute)
• del boot.ini (delete the file)
• BOOTCFG /Rebuild (This is the magic command – searches/fix/replace/repair any faulty system files)
• CHKDSK /R /F
• FIXBOOT (write to mbr)

6. Note that you need to use the /FASTDETECT as the OS Load Options. And if your pc runs on a Intel XD or AMD NX you need to use /NOEXECUTE=OPTIN in conjunction with /FASTDETECT

7. Congratulations.

Repairing windows made easy.
Thanks to Thrax for his original article

OLPC (One Laptop per Child) – The vision of Negroponte

When i first heard about his vision of closing the gap of information age between third world countries and developed ones by the OLPC project, i shrugg it off as a vain attempt. One year later, the first step towards his vision was made: The $100 laptop by MIT is out. Negroponte will be rememebered in history for his vision, in the same league as Richard Stallman, founders of Project Guttenberg etc. Check out the pictures of the US$100 laptop Check out the video of Negroponte's vision

Simulation Techniques & Modelling

Study Materials

1. Introduction to Discrete Event Simulation

2. Random Number Generators

3. Input Data Analysis

4. Verification & Validation

5. Output Analysis

6. Parallel and Distributed Systems

7. Distributed Virtual Environments

8. High Level Architecture – Data Distribution Management

9. High Level Architecture – Time Management

Projects

1. Telecommunication Exchange between two cities

2. Telecomm Channel usuage along a highway

3. Crisis Management

Links

1. Discrete Event Simulation

2. DES at IMIT

Welcome!

Welcome to Do no 3vil, home to my thoughts. Here be expected to find blogs in areas of computer science, technology, chrisitianity, psychology, philosophy and many more. These are my hobbies, my work, and my thoughts