Category Archives: Science

Last presentation in this semester


Last Wednesday was my last presentation for this semester. Our group did a project on testing four websites, Domain, RealEstate, CarsGuide, CarSales, CareerOne and Seek, using Metamorphic Testing.

We performed the test by generating a number of test cases, executing the test cases, and analyzing the result. Finally we compare the performance of each pair of the website.

We utilize Python, Selenium and BeautifulSoup module to execute the test cases and parse the HTML page to get the result of each test case.


Here’s the link of our slide:


CeBIT Australia 2017

CeBIT merupakan kegiatan pameran dan konferensi yang diadakan setiap tahun. Kegiatan ini menghadirkan pelaku bisnis di bidang IT dan dilaksanakan selama tiga hari. Seperti tahun sebelumnya, kegiatan CeBIT Australia tahun ini diadakan di Sydney International Conference Center dan International Exhibition Center, Darling Harbour, Sydney. Adapun tahun sebelumnya kami tidak dapat hadir karena jadwal kuliah pada saat itu masih penuh. Namun, tahun ini, Alhamdulillah bisa menyempatkan hadir di hari terakhir.  Setelah menempuh perjalanan sekitar dua jam dari Wollongong, saya tiba di tempat kegiatan sekitar pukul 9 pagi.

Dalam kegiatan ini, kami mengikuti StartUp conference, menampilkan pembicara yang berpengalaman membangun start-up. Banyak hal yang sangat bermanfaat untuk saya, terutama tips bagaimana memulai dan menjalankan sebuah start-up.

Tidak hanya perusahaan asal Australia, pameran dan konferensi juga dikuti oleh perusahaan dari luar negeri, termasuk Jerman, Taiwan, Filipina, Srilanka, dan tentunya Indonesia, sebagai tetangga Australia.

Yang sangat menarik bagi saya adalah mengunjungi sejumlah stand start-up. Banyak diantara mereka yang baru berdiri memulai bisnis digital-nya beberapa bulan yang lalu. Dari situ kita bisa belajar bagaimana membangun sebuah bisnis digital yang dapat menjadi disruptive technology. Hal lain yang menghibur saya adalah berkesempatan mencoba teknologi Virtual Reality (VR) di salah satu stand.

Internet surveillance and the privacy wars on Sunday Extra: Background Briefing

An interview with Cory Doctorow presented by Jonathan Green was broadcast on ABC Radio National on 29 November 2015. Doctorow stated that the internet is increasingly being used as a tool of surveillance by government security agencies, law enforcement and those with a profit motive. The data gathering activity that is done by the government is considered as not beneficial for citizens. Therefore, people ought to reject this program in order to protect their privacy.

Privacy is not about sharing nothing, but about knowing who is sharing what.  In the past, it was difficult to eavesdrop on other people’s conversations. However, when the telephone was introduced, it became easier to hear what other people were saying. There are many technology corporations which run their businesses by selling data, tapping technology, software, servers, and computing power to government agencies. Meanwhile, the NSA is developing surveillance techniques using drone technology. This fact indicates that in the future, the internet may be an uncomfortable place for democracy. The government intelligence agencies are shifting their activity from human intelligence to signal intelligence which targets video, phone, email and other kinds of electronic communication. It is also revealed that the NSA surveillance program monitors one of every 10,000 people. They use their technology not for targeted people but randomly. They do not necessarily need to know their targets, they just gather all the information they can for anything they need.

A simple thing that can help protect people from this surveillance activity is using cryptography. People can use many available encryption tools that help them to scramble information thoroughly. Government agencies need high technological understanding and a lot of time and space to break the encryption. As a result, people can have better protection for their privacy on the internet.



Internet Surveillance And The Privacy Wars On Sunday Extra: Background Briefing 2015, podcast, 29 November, ABC Radio, viewed 27 January 2016, <


Using reCaptcha v2 (No Captcha) on Laravel

Google has launched the new way to verify that your web visitors are not robots. As we know, it’s known as reCaptcha, but on the latest version it’s called No Captcha. Why? Because you don’t have to type anything but only a click on a check box.

Now, I want to show you how to add this captcha to a web application using Laravel framework.

To be straightforward, add this line to your composer.json in section “require”

        "greggilbert/recaptcha": "dev-master"

then run this command

php composer.json update

Next, Add Greggilbert\Recaptcha\RecaptchaServiceProvider to the service provider list in app/config/app.php

Run php artisan config:publish greggilbert/recaptcha

In app/config/packages/greggilbert/recaptcha/config.php, enter your reCAPTCHA public and private keys. You should create a new key pair in order to use No Captcha. (fill the public key with site key).


Add the following line into app/lang/[lang]/validation.php

"recaptcha" => 'The :attribute field is not correct.',

Open vendor/zizaco/confide/src/views/signup.blade.php

then add this line just after password confirmation div closing tag

{{ Form::captcha() }}

For validation, add these code to app/controllers/user/UserController.php

$rules = array(
 'g-recaptcha-response' => 'required|recaptcha',
 $validator = Validator::make(Input::all(),$rules);
// process the login
 if ($validator->fails()) {
 return Redirect::to('user/create')

Now, time for testing. Open your sign-up page and you will see the new look reCaptcha.



Optimizing Zimbra Servers CPU Wait Time

CPU stat illustration

CPU stat illustration

Yesterday, I was complained about our mail server’s performance.

At first, I checked the disk space and everything’s OK. From server statistics, I found that the processed messages (sending and receiving) was about a hundred per minute.

Then I checked the load of the server using top command, and the result showed that the CPU wa percentage was quite high, about 30 to 60 %.

Based on some references on the internet, it mainly was caused by amavisd service which is doing read and write operation  from and to disk. It’s better to change the location of amavisd temporary folder (/opt/zimbra/data/amavisd/tmp) to RAM disk.


Then I did these steps:

  1. zmcontrol stop as zimbra user
  2. Add the following line to /etc/fstab:

/dev/shm /opt/zimbra/data/amavisd/tmp tmpfs defaults,size=200m,mode=700,uid=2003,gid=2000 0 0



/dev/shm : the RAM disk device

/opt/zimbra/data/amavisd/tmp : the mount point (amavisd temporary folder)

size=200m : folder size

mode=700 : only zimbra user can do read, write, and execute

uid=2003,gid=2000 : UID and GID of amavis (usually same to zimbra user)


After restarting the server and starting the zimbra services (zmcontrol start) I found that the CPU wait time  now is about 5 to 20% and the performance seems better and faster 🙂


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