The need for cyber awareness

During my summer vacation last year, I joined the Ayudh youth camp in a small village in Brombachtal, near Frankfurt, Germany. It was a summer camp for young people with various workshops in areas ranging from sports, music, arts and science. I was very excited to be part of the anti-cyber bullying workshop. It is very important to be aware of various cyber threats to stay safe online and maintain privacy. This is even more important for children, who are always connected to the internet with lot of gadgets all the time without being aware of potential dangers.
As a part of the camp, we went to the Theodor Litt Schule, a middle school in the nearby town of Michelstadt. I joined the four day workshop for the school kids conducted by youngsters like me (20-30 age group). I must say that it was a great experience to be part of the Ayudh group. Lucia Rijker, former world champion in boxing was also part of the workshop. Lucia is called by the press as “The Most Dangerous Woman in the World”. It was indeed an awesome experience to spend time with her. She conducted sessions on “respect” stressing on the need for self respect as well as respect for others. Some of the discussions and informal sessions were so invaluable. Students opened up and shared private incidences from their lives. I got to know that the incidents happening on the cyber space leave deep imprints on the minds of children. Online identity is given more importance than necessary, having a huge impact on the self confidence of a child. There were multiple incidents where children use cyber space as a platform for bullying a friend/classmate by abusing with public posts/pictures/videos. There are even instances where the victim ended up suiciding unable to bear the shame, due to their videos/post becoming viral. Before we share or click like on a funny video of someone (could be even a stranger), we must think twice what we actually gain out of it. If the content makes fun of someone, we can decide to participate in harassing somone or not with a click. It is very important to realise this sense of responsibility for every action we do online. The workshop in total served as an enriching experience awakening respect for myself, fellow friends and others. We even made a small act (drama) to spread awareness against cyber bullying.


After the camp, I went to India, my home country. I got to know about an incident near my village. A 9th grade child committed suicide due to a fake relationship that he made online. I felt very sad about the incident. This tragic incident shows that there is an important need to make children aware about their activities online. I was very happy when I got a chance to go to Amrita Vidyalayam school, Kollam, Kerala and talk about the relevance of cyber security and privacy to about 150 school kids. In both the schools, in Frankfurt and Kollam, at different sides of the world, I noticed that it is a growing concern among teachers and parents about their kid’s safety online. It is alarming to know about more and more bad incidents on cyber bullying/cheating happening around the world. I will make use of every opportunity that I get to spread awareness regarding this issue. It is a collective responsbility of everyone to be aware of the pitfalls in cyber space. Being a student in computer security, I find the relavance of safety and security online as a strong motivation to continue in my field. Computer securty is a lot of fun as far as the technical studies are concerened. But it gives immense satisfaction to study computer security for me mainly because,  it also serves a strong social cause for serving the society today.

Why kids should learn computer science

I dedicate this post to all high school kids out there who like to know more about the science of computing.

Computer Science has transformed the way we live by influencing all major domains. What was science fiction yesterday, is science fact today, thanks to computer science. The boons of computing are all around us, from automatic translation of documents to driverless cars,  to smart phones that understand our speech and life patterns. Facebook or WhatsApp or Twitter has become an integral part of our social lives.  Travelling and exploring new places took a new dimension with Google maps in everyones pockets. Even health sector is deeply influenced by the new health apps. Education is yet another field. You can take courses offered by professors from world class universities like Stanford, MIT or Cambridge, sitting at your home. Think about movies. Do you remember how amazed you were to see Harry Potter with the magic wand, or Kung Fu panda showing his cool Kung Fu moves? How about seeing a drone flying in the sky, bringing you the Pizza that you ordered at your doorstep?

We live in a new digital era and we all benefit from computer science in one way or the other. There is a huge variety of areas that one could specialise once you study computer science. You could be a designer, playing around with layouts, colours, and user interactions. You could be a security engineer, where you find out how to attack a system and come up with strong defense techniques. You could be a game developer who makes all those cool games that you play  within your tablet.  You could be a software engineer who is interested in making algorithms for running robots, connecting large networks, faster data management etc.  Maybe you could be the one who finally builds the world’s first intelligent machine close to the human brain or even superior! These are just a few options out of hundreds of other cool things that you could do with computer science!

When I was fourteen, I had deep interests in arts as well as science. I used to love music, paintings, logic, and programming. When the time came for applying to college, I was confused what to study. I believe I made the right choice by choosing  computer science. Learning computer science enables you to have an outlook at the world without boundaries between arts and science.  The attitude of a maker and an artist is what is needed in the field of computer science. We can not  easily predict the jobs that will be needed in the next decade. So we need to think of what kind of a mindset would prepare us for an exponentially changing world. In the future,  most of the jobs that require repetition will disappear as traditional jobs are getting redefined.

As we see, the world is changing at a rapid speed with the influence of technology and the huge amount of information flow. We need designers, artists, architects, civil servants, teachers who all have a grasp of computing principles and data analysis. Knowing computer science is not just a career option; it is a need, and an added advantage to your skill set, in any field you chose to go in future. It expands your thinking, and it helps you to become a problem solver who is dynamic enough to adapt to the changing world and who is ready to learn new skills and collaborate with each other.

Note: Some thoughts are inspired from a discussion with my friend @karmakomik.

Libpcap to read pcap file

Following is a simple C program that allows you to read a pcap file using the libpcap library. The pcap is generated using Wireshark.

I tried this code in Visual studio. Don’t forget to add WPCAP in Property->Preprocessor->Preprocessor Definitions  and also wpcap.lib in Properties->Linker->Input-> Additional dependencies.

#include <stdio.h>
#include <pcap.h>

#define LINE_LEN 16

/* 4 bytes IP address */
typedef struct ip_address {
u_char byte1;
u_char byte2;
u_char byte3;
u_char byte4;

/* IPv4 header */
typedef struct ip_header {
u_char    ver_ihl;        // Version (4 bits) + Internet header length (4 bits)
u_char    tos;            // Type of service
u_short tlen;            // Total length
u_short identification; // Identification
u_short flags_fo;        // Flags (3 bits) + Fragment offset (13 bits)
u_char    ttl;            // Time to live
u_char    proto;            // Protocol
u_short crc;            // Header checksum
ip_address    saddr;        // Source address
ip_address    daddr;        // Destination address
u_int    op_pad;            // Option + Padding

/* UDP header*/
typedef struct udp_header {
u_short sport;            // Source port
u_short dport;            // Destination port
u_short len;            // Datagram length
u_short crc;            // Checksum

void packet_handler(u_char *, const struct pcap_pkthdr *, const u_char *);

int main(int argc, char **argv)
pcap_t *fp;
char errbuf[PCAP_ERRBUF_SIZE];
char source[PCAP_BUF_SIZE];

if(argc != 2) {

printf("usage: %s filename", argv[0]);
return -1;


/* Create the source string according to the new WinPcap syntax */
if ( pcap_createsrcstr(    source,            // variable that will keep the source string
PCAP_SRC_FILE,    // we want to open a file
NULL,            // remote host
NULL,            // port on the remote host
argv[1],        // name of the file we want to open
errbuf            // error buffer
) != 0) {

fprintf(stderr,"\nError creating a source string\n");
return -1;

/* Open the capture file */
if ( (fp= pcap_open(source,            // name of the device
65536,            // portion of the packet to capture
// 65536 guarantees that the whole packet will be captured on all the link layers
PCAP_OPENFLAG_PROMISCUOUS,     // promiscuous mode
1000,                // read timeout
NULL,                // authentication on the remote machine
errbuf            // error buffer
) ) == NULL) {
fprintf(stderr,"\nUnable to open the file %s.\n", source);
return -1;

// read and dispatch packets until EOF is reached
pcap_loop(fp, 0, packet_handler, NULL);

return 0;

void packet_handler(u_char *temp1,
const struct pcap_pkthdr *header, const u_char *pkt_data) {
struct tm ltime;
char timestr[16];
ip_header *ih;
udp_header *uh;
u_int ip_len;
u_short sport, dport;
time_t local_tv_sec;


/* convert the timestamp to readable format */
local_tv_sec = header->ts.tv_sec;
localtime_s(&ltime, &local_tv_sec);
strftime(timestr, sizeof timestr, "%H:%M:%S", &ltime);

/* print timestamp and length of the packet */
printf("%s.%.6d len:%d ", timestr, header->ts.tv_usec, header->len);

/* retireve the position of the ip header */
ih = (ip_header *)(pkt_data +
14); //length of ethernet header

/* retireve the position of the udp header */
ip_len = (ih->ver_ihl & 0xf) * 4;
uh = (udp_header *)((u_char*)ih + ip_len);

sport = uh->sport;
dport = uh->dport;

/* print ip addresses and udp ports */
printf("%d.%d.%d.%d:%d -> %d.%d.%d.%d:%d\n",



Suricata, Snort, Bro

Are you looking for a tool to use as an intrusion detection system for your network? Did you come accross the tools Suricata, Snort and Bro ? Are you wondering which tool you might want to use?

All the three tools are proven effective with their own exclusive features. Understanding the specific features of each of them and their differences will help you in deciding which tool would suite your need the best.

The article ‘Open Source IDS High Performance Shootout’ by SANS helped me giving a detailed picture about a comparitive study between the three. I would like to summarise the key points for you.


To give an overall picture, Snort and Suricata come under the category of a Signature based IDS while Bro could be called a behaviour based one. In Snort and Suricata, you need to specify rules based on already known knowledge about malwares. A sample rule set would like this:

alert tcp $EXTERNAL_NET any -> $HOME_NET 139
content:"|eb2f 5feb 4a5e 89fb 893e 89f2|"
msg:"EXPLOIT x86 linux samba overflow"

Suricata also mention about a very similar rule set.

Fig reference here.

Bro has a very different approach compared to the idea of rules. Bro works with scripts. A sample Bro script looke like:

@load protocols/ssl/expiring-certs

const watched_servers: set[addr] = {,
} &redef;

# Site::local_nets usually isn't something you need to modify if
# BroControl automatically sets it up from networks.cfg.  It's
# shown here for completeness.
redef Site::local_nets += {,

hook Notice::policy(n: Notice::Info)
	if ( n$note != SSL::Certificate_Expired )

	if ( n$id$resp_h !in watched_servers )

	add n$actions[Notice::ACTION_EMAIL];

For someone with a typical linux scripting mindset, the bro scripts looks very appealing. Bro provides a totally new scripting language that makes it a highly flexible platform compared to Snort and Suricata. But from the perspective of a beginner, it might be as well hard to master the Bro scripting compared to understanding the Snort and Suricata rulesets.


Snort is highly efficient in the scenario of moderate traffic with a single core processor. Based on architecture, snort uses 10% of CPU for parsing, 10-20% for normalisation and 70-80% of CPU for payload inspection and detection. In a test perfromed by SANS, Snort gave a perfomance of 500Mbps with 1 CPU core for 1000 signatures. For 4000 signatures, it required 2.4 CPU at a rate of 400 Mbps. It was found that a single instance of Snort is more efficient than Suricata with 50% less memory utilisation. Recent versions of Snort support PF-RING and PCAP acceleration providing support for higher traffic.

Suricata is more focused on large scale networks. In a way, it could be considered as an extension of Snort for large networks. In a scenario with a 45 CPU hosting 12 cores per CPU and 125 GB of RAM, the network throughput was 20 Gbps. Suricata had a very less packet drop of 7% while it was 53% in Snort. Suricata provides support for PF-Ring, AF packet, PCAP acceleration and NFLOG. It also works better with multi-threading. In snort the normalisation is performed for every instance while for Suricata and Bro, the normalisation is performed only once before multithreading. Suricata also support GPU cuda acceleration for pattern matching. There are also about 4000 file types build for file extraction and logging also providing MD5 matching.

Bro, as mentioned above is script driven IDS. Bro has support for clustering for high throughput environments. Bro provides a ‘worker’ based architecture to utilise multiple processors. Bro’s developers recommend allocating one core for every 80 Mbps of traffic that is being analysed. It also have features allowing to interact with other systems in the enterprise, send email messages, page on-call staff, or automatically terminate existing connections. Bro also works based on file hash extraction and matching with the use of publicaly available hash registers. It is important to notice that the processing per core is significantly low compared to Snort or Suricata. But Bro has built in capacity to spread the load across multiple machines via Bro cluster thereby proving greater scalability. But there have some research showing that the overhead of distributed processing slows down the performance. Thus the performance acceleration is applicable onlz till a certain saturation point.

 Snort is the perfect solution for a moderate traffic scenario, about 400 Mbps. There are also acceleration support like PFRing in the newer versions aimed at solving the high throughput scenarios. But for high thoughput systems with 10Gbps or more, Suricata is better due to its extensive support for large scalability. ISPs using 20Gbps could use Suricata effectively. Bro could be considered as a high throughput research environment due to its great flexibility. Its powerful scripting features is definitly a greater advantage compared to the rule sets in Snort or Suricata.

Reference :




[4] Sample snort signatures:

How to upgrade to Python 2.7 in Solaris 11

Following are simple steps to upgrade from default version (python 2.6.8) to python 2.7 in Solaris 11. Many of the python frameworks are build on top of python 2.7. Hence this might be a good fix to  solve many problems.

Download and install python 2.7 to your system using the following commands.

$ pkgadd -d
$ /opt/csw/bin/pkgutil -U
$ /opt/csw/bin/pkgutil -y -i python27 
$ /usr/sbin/pkgchk -L CSWpython27 # list files

The new version of python gets installed in the directory  /opt/csw/bin. Inorder to make the default version to the latest one, create a symbolic link as root to the new binary file:

$ ln -sf /usr/bin/python2.6 /usr/local/bin/python

Linear feedback shift register

Modern ciphers are classified mainly as stream ciphers and block ciphers. LFSR is a simple method to generate a stream cipher. 

Stream ciphers are generated by adding each bit of plaintext with long generated bits called the keystream. Keystream is made out of a small secret called the seed, which is developed into a very long sequence of bits. 

Stream ciphers are generally based on states, an update function that navigates from one state to another and an output. 

You can read more about LFSR here

Following is the implementation of LFSR in magma with the given specification:

INPUT: 	(P,L,t)  	
         - P is the connection polynomial for the LFSR
			- L is a list for the initial state 
(note that Degree(P) eq #L) 
			- t the length of the keystream that we get 
from the initial state

         - Ks is a List of length t which contains the keystream
			- S is a list of length t+1 which contains 
the states of the LFSR
			  (so S is a list of lists)

function RightLFSR(P, L, t)
	C:= Coefficients(P);


	for i in [1..t] do
		V[i]:=L[#L]; // The output value is
                             //the last bit of each stream excluding
                             //the last register value.
		//Shift the register to the right
		for j in [1..#L1]do
			if j+1 in [1..#L] then
				L[j+1] := L1[j];
			end if;
		end for;
		//XOR the values based on the polynomial
		for j in [1..#L] do
			S[j]:=L1[j]*C[j+1]; // The previous state of
                         // the register before
                          //shifting is taken to find the first bit.
		end for;
	end for;
return V;
end function;

RightLFSR(x^5 + x + 1,[GF(2)!1,0,0,1,0],8);
//Calling the function above

The divine manifestation

Mind works so strange.
For the past one year, I had told this
To myself, for plenty of times!
Haven’t you also felt the same?
At least once in your life?

I build palaces of dreams with imaginations..
I live in that world..
It makes me feel so real.
I find it hard to believe that the images that
I see in front of me are images..
They are not real.
The rails, the grass, the buildings,
the people, the cars, the dogs,
the birds, the mountains, the clouds,
They are all images, of my imagination.

I got an idea to feel myself in others.
Not very sure how that works.
But I just got a glimpse of it!
I found myself manifesting in different forms.
I found my body trembling out of pain.
All beings manifested from me.
May be that is also a part of my minds imagination.

That was just for a fraction of a second.
And then back to my dream of believing
That I am a tiny creature with an ugly body
with a huge mind full of garbage,
with a beautiful brain, so polished and new
the one which is the least used..

Aaah.. no.. don’t fool me again..
I am not this! I am that..
Seems like Maharshi’s dialogue when he left home..
But please don’t misunderstand..
That was just a desire..
Not the truth!
One day, I would reach that heights..
So high.. that the differences diminishes..
Like the view from an aeroplane..
I would see them all merging into one.
I would see them merging into me!

Until then, I need to play around
with the part of myself
that is cheating me showing a fake world.
I need to remember to wake up
Not to fall deep and deep into
the fallacies of imagination..
But to awake, I need a call
from the Divine mother..
Who needs to take me in her hands,
and fly to those heights,
that would diminish the differences..