It’s the Middleman – Proxy Firewall

How many of you have applied proxy for one of your friends during the attendance call in the class? If I assume, it’s a yes from everyone, you will have no difficulty in understanding this one. Proxy is someone who is acting on your behalf and acting as the middleman. We take a more detailed example in some time to clearly understand this.

A proxy firewall stands between a trusted and untrusted network and makes the connection, each way, on behalf of the source. When you as a user, will send a request to, say connect,, the request will go through the proxy firewall to check what request has been made. The proxy firewall will stop your connection, initiate a new connection on your behalf and wait for the incoming traffic. Surely, it finds that you have requested for a website which is quite known for leaking personal data, it stops the traffic and sends you a message that this website cannot be connected to. This is unlike the packet filtering firewall. Where a packet…

Which State are you in? I’m Stateful.

In continuation with our series on understanding the firewalls, the next type is the stateful firewall. This one remembers and keeps track of what packets went where until each particular connection is closed.

To understand this one, we need to take an example. If you watch a little bit of crime drama, you will find that in most cases the neighbor knows everything. He is spying day and night on you and others in the neighborhood. He knows that the man on the left side of the road deals in weed and goes out of the house in the night, the construction guy who takes long breaks inside the garage, the milkman who smiles and pours extra milk looking at the handsome guy that lives next door and so on.
Most of the well-known protocols have a sequence of connecting. For eg – If you consider the TCP protocol which is a connection-oriented protocol, it goes through three steps before a connection is established. This is commonly known as the 3-way handshake. If my system wants to communicate wi…

This One is all about Packets

In the earlier blog post on the basics of the firewall, we learned what exactly is a firewall and what does it do? It’s time to learn about the various types of firewalls and how do they function. I will dedicate one post each to the types of the firewall, thereafter jumping to the various kinds of firewall architecture.
Packet Filtering Firewall
The packet filtering firewall is the most basic of all the firewall types. Taking a cue from the earlier discussed analogy of postman, this type filters the information packets based on rudimentary parameters such as source and destination address, port numbers, traffic direction. A postman also looks at your letter and filters or segregates them on the basis of pin codes, destination address, etc.
Packet filtering is a firewall technology that makes access decisions based upon network-level protocol header values. The device that is carrying out packet filtering processes is configured with ACLs, which dictate the type of traffic that is al…

The Curious Case of Firewalls

If you are hearing about the term firewall for the first time, and consider it as a wall on fire, you are at the right place. Because that is the overall idea behind this!!!
Firewall is one of the most used terms in the field of information security. A lot of people think that deploying this wall of fire will solve all of their problems. Is that so? What is it that a firewall does? Does it come in all shapes and forms? What is actually a firewall? Can I use a virtual firewall?  And many more… All your queries will be solved in this multi-part series on the firewalls.
A firewall is used to restrict access to one network from another network. You can think of it as a fence which you implement to keep those pestering pedestrians at bay. The firewall can also help you segregate one network within the overall network from another network. It’s like a door which helps to separate various rooms. For example, if the security administrator wants to make sure employees cannot access the HR net…

Crime Prevention through Environmental Design (CPTED) Approach

Security design and access control are more than bars on windows, a security guard booth, a camera, or a wall. Crime prevention involves the systematic integration of design, technology, and operation for the protection of three critical assets-people, information, and property. Protection of these assets is a concern and should be considered throughout the design and construction process.
The most efficient, least expensive way to provide security is during the design process. Designers who are called on to address security and crime concerns must be able to determine security requirements, must know security technology, and must understand the architectural implications of security needs.
Consider the following picture of an office campus below. What do you observe? Note down what all do you think represents this campus.

Here are some important points worth mentioning : Well-Paved footpaths.Proper guidance of people entering and leaving by giving them a designated path to walk upon.…

Building Blocks of a Blockchain - Part 2

I strongly suggest that you read the first part before reading this part as I can assure you that the old man still has a long story to tell.
Blockchain involves a lot of technical terms which we are going to learn about in the second part. Thinking of running away, don’t, as we are going to understand each and every term and the complete functioning of blockchain through real-life analogies. So grab yourself something to eat and start reading…
What the old man suggested in the story was an example of DISTRIBUTED LEDGER TECHNOLOGY (DLT)? A distributed ledger is a type of database that is shared, replicated, and synchronized among the members of a DECENTRALIZED network. The distributed ledger records the transactions, such as the exchange of assets or data, among the participants in the network.

Taking cues from the story, the book of promises which the brothers maintained is the ledger book. A ledger book is a record of transactions which is maintained to ensure that no one forgets h…

Understanding Blockchain – Part 1

In the first part, instead of bombarding you with technical jargons, I will tell you a story. This story will form the basis of understanding the technical jargons which will get introduced in Part 2 of this series.
There once lived an old man who had 10 sons. They all lived together. The old man was a clever man. He made each son choose a different profession so that they all could help out each other. One farmed while the other one hunted, the third one made pottery while the fourth one became a milkman. Hence, all decisions were taken by him. The family lived in this manner for quite some time. However, all the produce was brought to the old man for distribution among the brothers. You can say the old man was a central authority.
The old man thought that since he has to die one day, he must think of a solution that the brothers can apply to distribute the various items they produced. He knew that the centralized authority which he has commanded over the years will not remain after h…

Digital Signature

We learned about the basics of cryptography in the first post. We then learned about the types of cryptography – symmetric and asymmetric (private and public key cryptography). Then we mixed both of them to get the hybrid aspect. As if this was not enough, intelligent minds mixed hashing into cryptography to produce digital signatures.
It’s time to learn about this new potion – Digital Signature. Before we delve into detail, we must understand what is hashing. Hashing is a method to ensure that the integrity of the message has not been compromised with. A one-way hash function is used for creating a hash that takes a variable-length string (a message) and produces a fixed-length value called a hash value. This hash value will only change if a change has occurred in the message. If there is no change, then the hash value will not change if you apply the one-way hash function 1 time or a 1000 times. Let’s take an example to understand this. 
Message: This blog really helps me to unders…

Hybrid Cryptography

We just love to mix things up. Well, yeah and why not? When we get the best of both the worlds, we can mix anything up. Even when it is so complex in itself like cryptography. In the last article, we learned about symmetric and asymmetric cryptography. It’s time to mix them both and explain you the hybrid concept.
We need to go back and recapitulate some points before we can move forward and appreciate the hybrid concept. In the symmetric cryptography, we understood that it is quite fast, however, the challenge was sharing the key between a large number of people. Everyone is required to keep the shared key as secret, and, if this gets compromised, the distribution of the key needs to be repeated again.  What if we could find a way to quickly transfer this key amongst multiple people without the dangers of compromising it? Asymmetric key offers secure key distribution but uses a lot of resources when multiple people are involved. It’s also quite slow and mathematically intensive.

Symmetric and Asymmetric Cryptography

Having learned about cryptography in the previous article, it is now time to learn about the types of cryptography. You are right, nothing is complete till we understand its types and subtypes and so on. Remember, your best friends, Alice and Bob!!! They are going to help us understand the types of cryptography.
Before we go into the details, we ought to recapitulate a few terms. 
1. Plain text – Data in a readable or understandable format. 2. Ciphertext – Random and unreadable text  3. Encryption – Process of converting plain text into cipher text. 4. Key – Sequence of random bits 5. Algorithm – Rules by which encryption and decryption will take place.
It is really important to clearly understand these terms, else, the journey ahead will be difficult. So lets us begin.
Cryptography algorithms are either symmetric algorithms, which use symmetric keys (also called secret keys), or asymmetric algorithms, which use asymmetric keys (also called public and private keys). I know, this can …