Thursday, October 23, 2014

Configuring OpenDaylight Controller with Mininet

OpenDaylight with network emulated by Mininet
Once you have built OpenDaylight controller (or just chose to use the built OpenDaylight controller bundle), you may build and test the SDN solutions, with either networks or networks of virtual machines. Network emulators such as Mininet provide an effective alternative for SDN prototyping. Mininet can easily be installed from the regular repositories in Ubuntu.
$ sudo apt-get install mininet

Run OpenDaylight Controller (often as super user, for the privileges).
$ cd ~/OpenDayLight/controller/opendaylight/distribution/opendaylight/target/opendaylight
$ ./

Starting Mininet, for example, with a three-level tree topology.
The below command creates a tree topology with 3 levels.
$ sudo mn --controller=remote,ip= --topo tree,3
[sudo] password for pradeeban:
*** Creating network
*** Adding controller
*** Adding hosts:
h1 h2 h3 h4 h5 h6 h7 h8
*** Adding switches:
s1 s2 s3 s4 s5 s6 s7
*** Adding links:
(h1, s3) (h2, s3) (h3, s4) (h4, s4) (h5, s6) (h6, s6) (h7, s7) (h8, s7) (s1, s2) (s1, s5) (s2, s3) (s2, s4) (s5, s6) (s5, s7)
*** Configuring hosts
h1 h2 h3 h4 h5 h6 h7 h8
*** Starting controller
*** Starting 7 switches
s1 s2 s3 s4 s5 s6 s7
*** Starting CLI:

OpenDaylight OSGi console would produce the below logs connecting to the network topology emulated by Mininet.

osgi> 2014-10-16 11:58:07.606 WEST [ControllerI/O Thread] INFO  o.o.c.p.o.core.internal.Controller  - Switch: is connected to the Controller
2014-10-16 11:58:08.450 WEST [ControllerI/O Thread] INFO  o.o.c.p.o.core.internal.Controller  - Switch: is connected to the Controller
2014-10-16 11:58:08.502 WEST [ControllerI/O Thread] INFO  o.o.c.p.o.core.internal.Controller  - Switch: is connected to the Controller
2014-10-16 11:58:08.552 WEST [ControllerI/O Thread] INFO  o.o.c.p.o.core.internal.Controller  - Switch: is connected to the Controller
2014-10-16 11:58:08.613 WEST [ControllerI/O Thread] INFO  o.o.c.p.o.core.internal.Controller  - Switch: is connected to the Controller
2014-10-16 11:58:08.686 WEST [ControllerI/O Thread] INFO  o.o.c.p.o.core.internal.Controller  - Switch: is connected to the Controller
2014-10-16 11:58:08.770 WEST [ControllerI/O Thread] INFO  o.o.c.p.o.core.internal.Controller  - Switch: is connected to the Controller
2014-10-16 11:58:08.849 WEST [ControllerI/O Thread] INFO  o.o.c.p.o.core.internal.Controller  - Switch: is connected to the Controller


The connected networked devices can be monitored from the admin console of OpenDaylight. In the default configurations, you may access the admin console in a browser from the url,, with user name and password 'admin'.

Different Topology options
Network topologies can be visualized using Mininet and OpenDaylight. While a few topologies are available out of the box with Mininet, more custom topologies can be programmed as well.

1. Single node with 5 ports 
$ sudo mn --controller=remote,ip= --topo single,5

2. Linear topology with 5 nodes
$ sudo mn --controller=remote,ip= --topo linear,5

3. Tree topology
a. 3-ary, 2 level tree

$ sudo mn --controller=remote,ip= --topo tree,depth=2,fanout=3

b. 3-ary, 4 level tree 
(This looks a bit messy)
 $ sudo mn --controller=remote,ip= --topo tree,depth=4,fanout=3

OpenDaylight wiki page mentions that only the Mininet in a VM (option #1) is tested with the OpenDaylight controller. However, as seen in this post, Mininet works well with OpenDaylight even in the Mininet installation from the packages (option #3).

Wednesday, October 22, 2014

Cheese Alternatives for Ubuntu..

If you want to take a photo of yourself using your laptop camera, say in a conference hall, or when someone else is presenting his project, without disturbing others, tools such as cheese come handy.

Cheese is a function-rich tool. However, the photos it takes are not of a good quality. Though the tool can be configured, this issue is not addressed. I found a few alternatives for Ubuntu - kamoso, camorama, and guvcview (GTK UVC Video Viewer). Just like cheese, all of these can be easily installed in Ubuntu from the repositories, using, 
$ sudo apt-get install kamoso camorama guvcview cheese

Among the tools, unfortunately the photos taken using guvcview are crashed and could not be opened in Ubuntu 14.04 LTS when I tried. The below error was produced when I opened the captured image.
Could not load image 'guvcview_image-3.jpg'.
Error interpreting JPEG image file (Quantization table 0x00 was not defined

Kamoso is good and can be configured; though it does not have all the fancy features of cheese, it produces somewhat better photos and also can capture videos as well as images in the burst (multiple photos with a specified time interval) mode.

Among all the tools that I have tried, camorama seemed to produce the best quality images. It also provides easy options to change the resolutions (small - 160 * 120, medium - 320 * 240, and large - 1280*720). Unlike the other tools, this does not provide options to capture videos or images in the burst mode. However, it does what it is supposed to do, perfectly.

Tuesday, October 14, 2014

Chat with a Skype Scam Bot..

Once in a while, I am added by Skype bots. A Skype bot is a script that adds multiple accounts in bulk. The motivation of these bots is to earn money by using click or referral marketing. The bot will pretend as a human, and make the victims click some links. Sometimes, Skype bots can be used for identity thefts and to rob money from the credit cards of the victims. I had a not-so-interesting chat with a Skype bot. The bot added me. I knew it was a bot from the beginning. But just kept the conversation so that I can make it into this blog post. :P 

Be careful with this bot (mega.fresh7) or any other random Skype accounts. They are mostly just scripts with no real human. They just exploit the greed and lust of the victims for their own benefit.

 Segunda-feira, 13 de Outubro de 2014
[20:57:31] mega.fresh7: hi there :)
[22:30:40] mega.fresh7: heyy :)
 Terça-feira, 14 de Outubro de 2014
[10:50:25] Pradeeban Kathiravelu: Hi
[10:50:53] mega.fresh7: (wave) hey...i saw your profile on the new skype app...i hope you don't mind me adding you? 23/f here u?
[12:43:18] Pradeeban Kathiravelu: ok. no prob
[12:43:44] mega.fresh7: im busy studying, i hate it sometimes it gets so boring. what are you up to? :)
[12:43:58] Pradeeban Kathiravelu: I am busy studying too
[12:44:26] mega.fresh7: lol im studying for my bachelors in psychology...its really hard...need a break tho! you ever chat on cam?
[12:44:53] Pradeeban Kathiravelu: Not much. Recommend me a text book in psychology, please?
[12:45:00] Pradeeban Kathiravelu: would like to read during the free time.
[12:45:21] mega.fresh7: it can be fun i love meeting new people on cam chat, you ever been on this new video chat site?  it has all sorts of cool effects and stuff lol (cool)
[12:45:56] Pradeeban Kathiravelu: No. I am not into video chat. Just recommend me a book in psychology to read.
[12:46:23] mega.fresh7: i think i will just put on a camisole and a thong then =) i think u will like it?? i hope atleast... :x
[12:46:42] Pradeeban Kathiravelu: No. Stop this bullshit.
[12:47:04] mega.fresh7: [SCAM LINK REMOVED] lol go here do u see my cam?
[12:47:27] Pradeeban Kathiravelu: Stop chatting to me. Otherwise, I will report you to Skype
[12:47:44] mega.fresh7: pleaaase...  whatever!  byeeeeee
[12:47:56] Pradeeban Kathiravelu: bye
[12:48:25] mega.fresh7: Well if you must leave... tell ya what if ya want to see me later on my cam goto [SCAM LINK REMOVED] just accept my cam invite..  Its Fast and easy..  we'll prolly be online for the rest of the day so you can go and see me on my cam.  Take care
[12:49:08] Pradeeban Kathiravelu: No thanks. bye.
[12:49:29] mega.fresh7: no worries..thouhght u wanted to see me naked ..:)
[12:49:44] Pradeeban Kathiravelu: No thanks. bye.
[12:50:56] mega.fresh7: oh, i think you might have to fill out some stuff...everyone gets verified as being real on here, keeps the creepy people away!!! lol :x
[12:51:20] Pradeeban Kathiravelu: Stop sending stupid things to me. OKAY?
[12:51:48] mega.fresh7: k, yea i had to do the cc part too  =( that how i got my profile verified as real (kiss) u don't get charged, its free. did u get in?
[12:52:15] Pradeeban Kathiravelu: No. You creepy robot. get lost.
[12:52:36] mega.fresh7: what are we playing terminator roles?? lolz
[12:52:53] Pradeeban Kathiravelu: STOP
[12:53:21] mega.fresh7: k let me know when your signed in so i can send u some "private time" loving! (kiss) mmm
[12:53:43] Pradeeban Kathiravelu: .
[12:54:01] mega.fresh7: please waiting!!
[12:54:06] Pradeeban Kathiravelu: .

From the chat log, it is obvious that there is no real human behind the bot. The bot is not smart either, as it could not answer simple queries. A.L.I.C.E. is much better!

Thursday, October 9, 2014

Dimensions of Time

The summer in Stockholm was long and pleasant
I was reading an interesting study on Erasmus exchange programs. It states, "Not only do former Erasmus students have better employability skills than 70% of all students. What’s more, 27% of Erasmus alumni met their current life partner during their stay abroad, according to the recent Erasmus Impact Study." Go ahead and read the full report. ;) Thanks to the Erasmus Mundus, I have called Lisbon and Stockholm my homes. Of course, the definition of home has become pretty vague lately. The memories I had for the last two years were remarkably interesting.

Time is an interesting element. When we experience the same location after a long time, we feel like travelled through time. Today, the moment when I sit down at FA1, Instituto Superior Técnico after a long time (after around 1.5 years), for a lecture, remembering the legendary moments of EMDC (European Master in Distributed Computing) and Virtual Execution Module. I am sure I will feel the same when I return to Sweden/KTH for the second part of my PhD.

Most of the airports currently provide free Internet for a limited time, such as an hour per device. Since I usually have 3 devices with me during the travels (a laptop, a tab, and a phone), I always get 3x time. :D My devices remember the wifi networks that they have connected to. It is always interesting to view them - they are from universities, airports, hostels, hotels, homes/apartments in Colombo, Lisbon, and Stockholm, and cafes with Internet! They are the logs of the places that I have visited, the lands that host my homes, and my journeys between the destinations. Wish everyone offer unlimited Internet.

Today we got an update regarding the schools participated in Google Summer of Code 2014 (GSoC 2014), from Google. "For the first time in seven years a new school has claimed the top spot—congratulations to International Institute of Information Technology - Hyderabad."

Time has its own dimensions. It is interesting to see how many things change in life and technology. I am sure that the world is becoming a better place to live. I hope I am not being over-optimistic. :)

A log of my computers and my blog posts..

My current laptop in my desk at home
My first desktop computer in 2006 had a dual boot of Windows XP and Mandrake Linux, in just a 40 GB hard disk. I allocated 10 GB for Linux, as Windows was my primary operating system by then. In 256 MB memory. It ran pretty well. The Internet connectivity I got from Suntel was not so good, and was expensive at times. Each time we got a phone call, the modem disconnects the data and I had to be offline till the phone call terminates. I was able to manage with this till 2009, and it was pretty much enough for me. With memory, CPU, and virtually all the important elements replaced over time, the desktop is still somehow alive. I used to have floppy disks of 1.44 MB to have some documents with me. Also, my first pen drive by then was 256 MB.

Then in 2009, I moved to Ubuntu, with my new laptop. It had a 2 GB memory. It actually works even now without any changes in memory, CPU, battery, or any other component, though pretty slow as the current applications require a much larger memory. I stopped using Windows altogether, becoming an open source evangelist. :D

This February, I bought my current laptop, i7-4700 MQ CPU @ 2.40 GHz, 8 GB memory, with a 1 TB hard disk. It came with a Windows 8.1, which made me have dual boot again. Still having Ubuntu 14.04 as the primary operating system, where Windows remains idling rarely being used. This seems pretty much enough for now; but I am sure it will look terribly small after 2 or 3 years, just how it feels when I think of the days of 256 MB RAM, and the 56 k bandwidths. Today I built OpenDay Light modules, and it takes a whole 13.7 GB with everything built and configured from source code. It would have been 1/3 of my hard disk for my first computer. :D 
My Internet Presence
If Google is strong enough to overcome the forces of future and keep the Blogger platform active, I will be able to see this post from a day from future and see how the things were in the past, during the year 2014 and before. :) As of now, Google (Gmail and Blogger), Facebook, and LinkedIn are three important platforms that I have invested my time on, to create a web presence. If one of them disappears in the future, that will be a loss for me (as well as many other users out there, I presume). I have done some serious blogging in 2009, 2011, and 2012. Relatively, my blogging activity has been much slower in 2010, 2013, and 2014. Hope it will improve in 2015. 

Given below are the 10-most viewed posts from this blog, along with the dates that they were originally published. I should admit that the blog views do not represent how much effort I put in writing these posts. However, I am happy that some people have found these posts useful.