Other :: Cybersecurity :: Networking ::
The Internet is basically insecure. Why? you ask?.. first of all, the internet was not originally built to be what it is today. The analogy usually given to us kids is.." It’s like someone decided to expand a shoe box into a skyscraper." So, the internet originally developed when computers were huge and so expensive to own that only universities, big businesses, and a few governments had them. Originally, it was to let these massive supercomputers talk to each other & soon as two computers could send information back and forth, we had a network. The network gradually grew, until personal computers emerged in the 1980s, and then it exploded. Soon people were not just talking to each other, but also exchanging money, playing games, reading news, shopping, and doing everything we associate with the internet today!
Network Layers: While networking is often discussed in terms of topology in a horizontal way, between hosts, its implementation is layered in a vertical fashion throughout a computer or network.

What this means is that there are multiple technologies and protocols that are built on top of each other in order for communication to function more easily. Each successive, higher layer abstracts the raw data a little bit more, and makes it simpler to use for applications and users. It also allows you to leverage lower layers in new ways without having to invest the time and energy to develop the protocols and applications that handle those types of traffic.

The language that we use to talk about each of the layering scheme varies significantly depending on which model you use. Regardless of the model used to discuss the layers, the path of data is the same. As data is sent out of one machine, it begins at the top of the stack and filters downwards. At the lowest level, actual transmission to another machine takes place. At this point, the data travels back up through the layers of the other computer.  Each layer has the ability to add its own "wrapper" around the data that it receives from the adjacent layer, which will help the layers that come after decide what to do with the data when it is passed off.

Before we begin discussing networking with any depth, we must define some common terms.
A Packet:
Packet is, generally speaking, the most basic unit that is transfered over a network. When communicating over a network, packets are the envelopes that carry your data (in pieces) from one end point to the other.

A protocol?
Protocol is a set of rules which govern how system communicate with each other. Then we need to know what a Protocol suite is.A protocol suite is simply a collection of protocols that are designed to work together.
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TCP/IP Model:

The TCP/IP model, more commonly known as the Internet protocol suite, is another layering model that is simpler and has been widely adopted. It defines the four separate layers, some of which overlap with the OSI model:
  • Application: In this model, the application layer is responsible for creating and transmitting user data between applications. The applications can be on remote systems, and should appear to operate as if locally to the end user.
The communication is said to take place between peers.
  • Transport: The transport layer is responsible for communication between processes. This level of networking utilizes ports to address different services. It can build up unreliable or reliable connections depending on the type of protocol used.
  • Internet: The internet layer is used to transport data from node to node in a network. This layer is aware of the endpoints of the connections, but does not worry about the actual connection needed to get from one place to another. IP addresses are defined in this layer as a way of reaching remote systems in an addressable manner.
  • Link: The link layer implements the actual topology of the local network that allows the internet layer to present an addressable interface. It establishes connections between neighboring nodes to send data.
As you can see, the TCP/IP model, is a bit more abstract and fluid. This made it easier to implement and allowed it to become the dominant way that networking layers are categorized.

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