Showing posts with label Linux. Show all posts
Showing posts with label Linux. Show all posts

Monday, June 22, 2009

How to create a secure, memorable PIN number

Usually people will use their existing numbers, such as telephone number, house number, birth date or social security number as their PIN number for banking. These numbers are easy to remember, nevertheless easy to be broken.

This article will give an idea on how to create a secure, but memorable PIN number.

How to create the PIN number

The technique is so simple. You need to create your own simple algorithm to generate the PIN number, based on the number that you already memorized. In case you forget the PIN number, it can always be generate easily using the algorithm.

An example of algorithm

Let say you want to generate a PIN that consists of six digits.

  1. First create the secret number. Think of a 3 digits number that you won’t forget. For example, if you are born in 1965, you can use 965 as the secret number.

  2. Use your algorithm to create the PIN number.
    Example: Add the secret number in step 1 with the number one, and multiply it back to itself.
    965 * (965 +  1) = 932190

  3. Therefore, your PIN number is 932190.

Different PIN number for different bank

Using this technique, you will have a PIN number that cannot easily be guessed by others. But, what if you want different PIN number for different bank?

You can also create different PIN number for different bank, using the same algorithm and secret number.

Just associate bank1 with 1, bank2 with 2, and bank3 with 3. Then, you can replace the number one in your algorithm with two for bank2 and three for bank3.


This article shows on how to create PIN numbers from one secret number and an algorithm. Using this technique you will only need to remember the secret number, the algorithm and the bank association number.

Friday, May 29, 2009

Wednesday, April 29, 2009

Command lines to install or remove packages in Ubuntu

To install a package

sudo apt-get install the-package-name

To remove a package

sudo apt-get remove the-package-name

Remove automatically installed packages that are no longer required inUbuntu

Installing and removing packages in Ubuntu will leave unneeded packages.

To remove those packages, use this command:
sudo apt-get autoremove

Tuesday, April 28, 2009

Using keyboard shortcut to switch between workspace in Ubuntu

You can switch or move active application between workspace using these keyboard shortcuts:

  1. Ctrl + Alt + left/right arrow will switch to the next or previous workspace.

  2. Windows Key + E will show all the workspace. Use left or right arrow to move between workspace.

  3. Shift + Ctrl + Alt + left/right arrow will move the active application to the next adjacent workspace.

Monday, April 27, 2009

Enable Ubuntu public_html user directory for Apache

The steps to make http://localhost/~username works in Ubuntu.

  1. Create public_html directory in home directory
    mkdir ~/public_html
  2. Enable the user directory
    cd /etc/apache2/mods-enabled
    sudo ln -s ../mods-available/userdir.conf userdir.conf
    sudo ln -s ../mods-available/userdir.load userdir.load
  3. Restart Apache
    sudo /etc/init.d/apache2 restart

Set Ubuntu Time Zone

To set Ubuntu time zone,
  1. Click on System > Administration > Time & Date.
  2. Click on Unlock. Enter the password.
  3. Click on Time zone. Use the map or Selection to select your country.
  4. Click Close when your are done.

Sunday, April 26, 2009

Customize Firefox print margins, header and footer

To customize the margin, header or footer of Firefox print, click on File > Page Setup. Then click on the "Margins & Header/Footer" tab.

Choose "--blank--" to remove any item. To add your own text, choose "Custom". A box will pop up waiting for the you to add your own text.

Click on OK when you are done.

Firefox tab keyboard shortcut

Ctrl+T: opens a new tab
Ctrl+1: Switch to the first tab
Ctrl+2: Switch to the second tab
Ctrl+3: Switch to the third tab
Ctrl+4: Switch to the fourth tab
Ctrl+5: Switch to the fifth tab
Ctrl+6: Switch to the sixth tab
Ctrl+7: Switch to the seventh tab
Ctrl+8: Switch to the eighth tab
Ctrl+9: Switch to the LAST tab
Ctrl+=: Zoom in
Ctrl+-: Zoom out
Ctrl+0: Reset the zoom to normal

Wednesday, April 22, 2009

How to install IDLE in Linux

IDLE is the default editor for Python. However, despite the fact that Python is installed by default in most Linux system, the user should install IDLE manually. These are the commands for installing IDLE.


sudo apt-get install idle

Fedora/Red Hat

yum install python-tools

Friday, April 3, 2009

Batch shrink multiple images by drag and drop with Shrink O'Matic

Shrink O'Matic is a freeware Adobe AIR application for resizing images of JPGs, GIFs and PNGs types. It has a simple gui and very easy to use. However, you need to have Adobe AIR installed to run.

Click here to install.

Thursday, April 2, 2009

Adobe Reader 9 for Linux

Adobe Reader (Acroread) 9.3-1 for Linux. Note that version 9.0 was skipped.

Download links:

AdbeRdr9.3-1_i386linux_enu.deb (60.5Mb)

Last update: Wednesday, January 13, 2010

Friday, March 20, 2009

Quick list of unix shell commands

Some Unix or Linux shell commands.

Cancel a command

Ctrl+U, Ctrl+X, or @

Change the working directory to /usr

cd /usr

Change the working directory back to your home directory


Copy a file

cp oldfile newfile

Copy a file to another directory

cp oldfile dirname

Copy a bunch of files (e.g. filename1, filename2, ...) to another directory

cp filename* dirname

Copy all the files in this directory and in all its subdirectories

cp -r * newdir

Erase a file

rm filename

Rename a file

mv oldname newname

Move a file to another directory

mv oldfile dirname

List filenames


List filenames with sizes and dates

ls -l

List hidden files too

ls -al

List files and pause when screen is full

ls | more

Look at a text file

cat filename

Look at a long text file

more filename

Make a new link (name) for a file

ln oldname newname

Make new links (names) for files in a directory

ln dirname/* newdir

Combine two files

cat file1 file2 > newfile

Compare two files

diff file1 file2

Look at the manual page for the ls command

man ls

Change your password


Sunday, March 8, 2009

Solid but easy to memorized password

Composing a solid password is easy. A combination of alphanumeric and symbols, creates one. However, this kind of password is not human friendly. It is usually hard to memorize. Moreover, since a good practice is to have different password for different purposes, it will became more trouble for human.

To create an easy to memorize password, you can use the acronyms of your favourite phrase of music, poetry, quote, or simple sentences. For example, 'Make everything as simple as possible, but not simpler.' by Albert Einstein could be abreviated as 'measap,bns.'. Or, you can use a combination of small and capital letters such as 'mEaSaP,bNS.'

Now, you have a strong, but, easy to memorize password. However, what about the rule that you should not use the same password for everything. Fortunately, there is a simple trick to use. For example, 'measapbns' is the base password. To use it in Facebook, you can for example precede the base password with 'FB'. So, your password for Facebook would be 'FBmeasapbns' or 'FB-measapbns'.

The technique presented in this article is just a guide, for you to create your own technique in creating a solid but, easy to memorize password. Maybe you can come out with a simpler but better technique, such as replacing some letters with numbers, such as i with 1, or o with 0.

Good luck.

Saturday, March 7, 2009

Uncompress files online

WobZIP is an online service for uncompressing compressed file online, from a url without first download the compressed file to your computer. The compressed files will be scanned using an anti-virus scanner, and any infected files will be removed. WobZip works with .rar, .7z, .tar, iso and many other compressed file types.


WobZIP interface

Saturday, February 21, 2009

How to send email with large attachment

Figure 1: filesfrom screenshot

Email services will usually restrict the size of email (the attachment plus the email content itself) send or receive. For example, Gmail only permit up to 20 megabytes (MB) in size.

An alternative to send large file, is to host it elsewhere, and send the link to the recepient, to download. Some free file hoster are SaveFile, MediaFire, and RapidShare. What we need to do are first, upload the file to the free file hosting service. Second, grab the file link, and third, email the link to the recepient.

However, we can actually reduce the number of steps to just one, using the free service from filesfrom. Just enter the sender and recepient email addresses, choose file to upload, and click send, in the provided form, as shown in Figure 1.

Sunday, January 11, 2009

4 free icon sites

There are thousands of amazing icons that you can download from the Internet. These are some of the free sites.
  1. CoolArchive

    Host over 4000 icons in 125 categories. All the icons are available in both .ico (for your computer) and .gif (for your web page) formats.

  2. All Free Original Clip Art

    Over 30,000 Free Clip art Images, such as animated gifs, icons, backgrounds, bullets, clip art, and pictures.

  3. IconPlus

    A freeware icon site dedicated to creating cool comic book, sci-fi, tv, movie, and other pop culture icons.

  4. IconArchive

    Contains over 22,200 icons in 800 sets from 198 icon authors.

Friday, December 19, 2008

Ubuntu: Make Pidgin run at startup

We can have Pidgin to run at startup in Ubuntu using the Sessions Preferences tool.

Click System > Preferences > Sessions.

Under the "Startup Programs" tab, click Add.

Type Pidgin in the Name text box, and pidgin in the Command text box.

From now on, Pidgin will start automatically.

Monday, November 17, 2008

Backup, sync and secure folders with Toucan

Toucan is a small freeware that allows us to synchronize, backup and secure your data. The GUI is so simple and divided into seven tabs, allowing us to easily find the function that we need.

 There are four synchronization mode for Toucan: copy, update, mirror (copy/update) and equalize.

As for the backup function, Toucan supports complete, update and differential type. The backup file can be in the format of zip or the smaller size 7-zip.

The third feature of Toucan, secure data, use AES-256 encryption via ccrypt. AES is one of the most popular algorithm used in symmetric key cryptography. AES is fast and also require less memory.

As a conclusion, Toucan is not only a good and simple tool for backup and synchronization tasks, but can also encrypt important files and folders.

If you have any other suggestions, please don't hesitate to leave a comment.

  1. Toucan:
  2. AES:
  3. ccrypt:
  4. 7-zip:

Wednesday, September 10, 2008

Sending big files

Ever wonder how to send big files to your friend?

Try You can send any size of file, without any software install. Of course, you will need the web browser.

Your friend could start downloading the file as you are uploading.

Pipebytes claims that this service is time saving and secure. The transfer will started as soon as your friend starts the download process, since Pipebytes does not store the file. Pipebytes will only act as a data transfer pipe, that allows users to directly transfer files between peers.

However, in case of interrupted transfer, resume is not supported. One solution is break the file into small chunks, before sending using Pipebytes.

Another problem is, that you can only send file to one person at a time.

About the "secure" term, I think if we are on a corporate network (even home network), the system administrator (parents) could potentially intercept the data. As

In spite of all that, Pipebytes provides a free, real time, ad supported service, for users to transfer big files to one friend, without saving the file in the server, initially.

Happy transferring.