Network security

Networking fundamentals (for network security professionals)

September 17, 2020 by Nitesh Malviya


To understand Network Security, it’s imperative that we understand networking fundamentals and networking basics. In this post, we will be learning about networking basics and fundamentals to get started with Network Security. 

We cannot cover whole networking in a single post so we will be focusing only on core networking concepts needed for network security.

What is Computer Networks

Computer Network is the network of computers connected with each other either wired or wirelessly to share and exchange information and resources with each other. These connected computers share and exchange data with each other using some common communication protocol.

Hardware Devices

In a computer network, numerous hardware devices are involved. Majorly following hardware devices are required to set up a computer network:

  1. Network cables
  2. Router
  3. Hub
  4. Switch
  5. Network Interface Card (NIC)
  6. Distributors
  7. Universal Serial Bus – USB

Network Topology

Following Network Topology is widely used in Networking – 

  1. Bus network
  2. Star Network
  3. Mesh network
  4. Ring network
  5. Tree network
  6. Fully connected network

OSI Model

OSI stands for Open System Interconnection. It is a reference model which specifies how a communication should happen between two computers. 

It has 7 layers namely – Physical, Data, Network, Transport, Session, Presentation and Application layer for establishing communication and sharing and exchanging  data between two computers.

IP Address

An IP address is also called a logical address. To identify devices on the internet, each device is assigned a numerical label called IP address. This IP address is unique 

for each device and two devices cannot have the same IP address. It is using these IP addresses, devices identify each other and share and exchange data for communication.

An IP address can be IPv4 or IPv6. An IPv4 address is 32 bit in length while an IPv6 address is 128 bit in length. Also, an IP address can be public or private depending upon the network configuration and settings.

MAC address

It is also known as a Physical Address. The Mac Address is associated with its network interface card (NIC) and is assigned to NIC at the time of manufacturing. The length of the Mac Address is 6 bytes or 48 bits.

Port Number

A port number is basically a unique identifier to identify a particular service running on any system. Example – port 80 is used to run HTTP service. A port number is 16 bit in length therefore we have 2^16 ports available to use. Thus the number of ports available is 65535.


  1. Well known ports – 0 – 1023
  2. Registered ports – 1024 – 49151
  3. Ephemeral ports – 49152 – 65535

Domain Name Server

Also known as DNS. Domain name server is used to translate URLs to their corresponding IP address. Thus, a user does not have to remember the IP address of any website.


It stands for Address Resolution Protocol. It is used to convert an IP address to its physical address. ARP works at Data Link Layer to identify the Mac address of the machine.


It stands for Reverse Address Resolution Protocol. It converts MAC address to an IP address and works exactly opposite as of ARP Protocol.


Though all the networking concepts cannot be covered in a single post, this post covers major concepts required to get started with Network Security.



Posted: September 17, 2020
Nitesh Malviya
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Nitesh Malviya is a Security Consultant. He has prior experience in Web Appsec, Mobile Appsec and VAPT. At present he works on IoT, Radio and Cloud Security and open to explore various domains of CyberSecurity. He can be reached on his personal blog - and Linkedin -