Networking With SAPT-0x02: Basic Networking Terms

8 min readOct 30, 2021

Hello guys👋👋 ,Prajit here from the BUG XS Team . Welcome back to my write-up series, “Networking With SAPT”, which will help all those who want to learn networking, and I will start from complete basics, so anyone who doesn’t know a thing about computer networks, can start learning from here That being said, let’s start our chapter 0x02: Basic Networking Terms

Internet: The internet is a collection of infinite numbers of connected computers that are spread across the world.

Protocol: Protocol is an established set of rules that determine how data is transmitted between different devices in the same network.

NIC: Network Interface Card (NIC) is a hardware component without which a computer cannot be connected over a network. It is a circuit board installed in a computer that provides a dedicated network connection to the computer. It is also called network interface controller, network adapter or LAN adapter.

MAC Address: A Media Access Control Address is a unique identifier assigned to a NIC to use as a network address in communications within network segment. It is a 12 digit hexadecimal number.

Server: A server is a computer program or device that provides functionality for other programs or devices called “clients”

Client: A client is a piece of computer hardware or software that accesses a service made available by a server.

Port: Port is a connection point or a virtual point where network connections start and end. Ports are software-based and managed by a computer’s operating system. Each port is associated with a specific process or service. Ports allow computers to easily differentiate between different kinds of traffic: emails go to a different port than webpages, for instance, even though both reach a computer over the same Internet connection. There are total 65535 ports.

Some common port number and their service

Visual Representation of Client-Server Interaction

Peer-Peer Network: Computers are connected together so that users can share resources and information. There is no central server present here and each of them works as both client and server.

The Network Core

This defines the connection of different network segments together and process to show how packets are transmitted across the network.

This is implemented through the use of switching techniques. There are mainly two types of switching techniques.

Circuit Switched Network: A dedicated channel has to be established before the call is made between users. The channel is reserved between the users till the connection is active. This is mainly used for real time services like voice communication etc. For one way communication one channel is allocated and for two way communication two channels are allocated.
Packet Switched Network: It is not required to establish the connection initially. It is already available to use by users. One drawback is that if traffic increases then it will lead to congestion in the network, hence this is mainly used for non-real time services.

Difference between circuit switching & packet switching

Transmission Media

A transmission media can be defined as any medium that is used to carry information from a source to destination.

There are mainly two types of transmission media :

Guided Media (Wired):

Guided media are those that provide a wired-channel from one device to another. There are three types of Guided Media.

Twisted Pair Cable: In this wires are separately insulated and then twisted together. It is widely used in different kinds of data and voice infrastructure. The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction. There are two types of twisted pair cable.

a. Unshielded Twisted Pair (UTP): This is ordinary telephone wires and are less expensive. It has weak immunity against noise and interfaces and is used in laboratory.

b. Shielded Twisted Pair (STP): This has an extra metallic shield on each pair and are relatively more expensive. They give better performance than UTP and used in exterior network.

2. Coaxial Cable: In this, outer conductor is braided shield, inner conductor is solid metal and is separated by a insulating material and whole cover by plastic. This is used in television , etc. as they have high bandwidth and excellent noise immunity.

3. Fiber Optic Cable: This is made of glass or plastic and transmits signals in form of light, as light travels in a straight line as long as it is moving through a single uniform substance. It is surrounded by a cladding of less dense glass or plastic. It has small size and weight as well as high data rate & lower attenuation. Here bandwidth loss is less hence it is used in high bandwidth network.

Visual Representation of Fiber Optic Cable

Unguided Media:

Unguided media transmit electromagnetic waves without using a physical conductor. This is often referred to as wireless communication. There are three types of unguided media.

Radio Wave: These work through omni-directional antennas and waves can penetrate through walls, also the sending and receiving antennas need not to be aligned. It is used for multicast communications, AM and FM radios and cordless phones use radio waves for transmission. Its frequency range is 3KHz to 1 GHz.

2. Microwave: These work through directional antennas, point to point communication and since these are higher frequency waves, they cannot efficiently penetrate walls. It is used for unicast communication such as cellular telephones, satellite networks. Its frequency range 1GHz to 300GHz.

3. Infrared Wave: These can be used for short-range communication in a closed area using line of sight propagation. It is relatively directional, cheap and easy to build , but they do not pass through solid objects. It is used on televisions, VCRs and stereos all use infrared communication.

Network Devices

Repeater: This will repeat the signals from one port to another. n important point to be noted about repeaters is that they do not amplify the signal. When the signal becomes weak, they copy the signal bit by bit and regenerate it at the original strength. It is a 2 port device.

Hub: This is basically a multiport repeater and is used to repeat the signal. A hub connects multiple wires coming from different branches, for example, the connector in star topology which connects different stations. Hubs cannot filter data, so data packets are sent to all connected devices.

Switch: This can be called as intelligent hubs. It can perform error checking before forwarding data, which makes it very efficient as it does not forward packets that have errors and forward good packets selectively to the correct port only. In other words, the switch divides the collision domain of hosts, but broadcast domain remains the same.

Bridge: This is used to learn MAC Address in a software. It is also used for interconnecting two LANs working on the same protocol. It has a single input and single output port, thus making it a 2 port device.

Routers: It is a switch like device that allows us to route from one network to another. It normally connect LANs and WANs together and have a dynamically updating routing table based on which they make decisions on routing the data packets. Router divide broadcast domains of hosts connected through it.

Firewall: Firewall along with some rules specify what traffic is allowed or denied for security. Our home router has a built in firewall.

Intrusion Detection System (IDS): It analyzes and monitor network traffic for signs that indicate attackers are using a known cyberthreat to infiltrate or steal data from your network. IDS systems compare the current network activity to a known threat database to detect several kinds of behaviors like security policy violations, malware, and port scanners.

Intrusion Prevention System (IPS): It lives in the same area of the network as a firewall, between the outside world and the internal network. IPS proactively deny network traffic based on a security profile if that packet represents a known security threat.

Now this is all about this chapter, hope you liked it, if you found this informative, do not forget to clap👏 and do let me know if you have any doubts✌️. In the 0x series we will be discussing all the basics of networking before deep diving into it, so next writeup will be of one more 0x series. Also feel free to give suggestions on write-up or how the flow of content is showing. I am aiming to write one each week, and if possible I would write more in a week. Do follow for future chapters updates.😁

Thanks For Reading 😊