CCSA#2

Basics of Computer Network

Disclaimer:

Usage of these information/Data/Tools/Techniques for attacking targets without prior mutual consent is illegal. It's the end user's responsibility to obey all applicable local, state and federal laws. The Computer Joker/Instructor/Owner assume no liability and are not responsible for any misuse or damage caused by this program. Only use for educational purpose. The Computer Joker/Instructor do not support/promote hacking. For more details, head to our t&c page.

what is a network?

Network can be termed as “collection of two or more computers/systems connected with each other for communication and other purposes”.

Purpose of computer network

1. Communications

2. Data/File/Resource sharing

What is internet?

The Internet is a global network of billions of computers and other electronic devices.

With the Internet, it's possible to access almost any information, communicate with anyone else in the world, and do much more.

In general, internet can be referred as “Network of networks

what is networking?

Networking, also known as computer networking, is the practice of transporting and exchanging data between nodes over a shared medium in an information system.

Networking comprises not only the design, construction and use of a network, but also the management, maintenance and operation of the network infrastructure, software and policies.

some networking terms

Node › Any system, which is a part of the network is called “node” or “host”.

Bandwidth › Bandwidth is the maximum rate of data transfer across a given path.

Data rate › Data rate is the number of bits that are transferred/processed per unit of time.

Latency › Network latency is the time it takes for data or a request to go from the source to the destination.

Types of network based on the medium

Wired ›

Broadband, telephone lines & etc

Wireless ›

Bluetooth, wifi, infrared, satellite, cellular & etc

Types of network on basis of scale

LAN

Local Area network › In a library or a campus 

MAN › Metropolitan Area Network › Wider geographical area then LAN. Several buildings of a city.

WAN › Wide Area Network › Entire globe. Such as Internet

networking components

Switch

A switch is a device in a computer network that connects other devices together. Multiple data cables are plugged into a switch to enable communication between different networked devices.

Router

A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet.

networking protocols

Network protocols are sets of established rules that dictate how to format, transmit and receive data.

Protocol/Service - Port Number

FTP –File Transfer Protocol - 21

SSH –Secure Shell Protocol - 22

Telnet –Remote Login - 23

SMTP–Simple Mail Transfer Protocol - 25

DNS –DomainName System - 53

HTTP –Hypertext Transfer Protocol - 80

POP3 –Post OfficeProtocol - 110

HTTPS –HTTP Secure - 443

MySQL –MySQLDatabase Service - 3306

packet switching

Packet switching is the transfer of small pieces of data across various networks.

These data chunks or “packets” allow for faster, more efficient data transfer. 

Often, when a user sends a file across a network, it gets transferred in smaller data packets, not in one piece.

Networking model - OSI

Open System Interconnection Model

Layer - Function

Application Layer - User Interface

Presentation Layer -  Data presentation/ Formatting

Session Layer - Session handling ( Creation & maintain )

Transport Layer -  TCP ( Data management )

Network Layer - IP ( Routers )

Data Link Layer - Switches & MAC

Physical Layer - Signaling and cables

Client - server model

Client-Server model also known as Request-Response model where One machine host services and act as a server while other system can request services from the server over the network/internet.

What is IP address?

Full form of IP is Internet Protocol

IP address is a unique number assigned to all the systems/devices connected in the network/internet

For example › 216.58.203.14 ›

Two types of IP address:

1. Private (192.168.2.2) – Starts with 10, 172 & 192

2. Public (216.58.203.14)

How to find Private IP address of your system?

How to find Private IP address in Windows system.

Press windows key › Type “CMD” & enter – A black window will be opened

Type “ipconfig” and press enter

Go down and you will see you IP address in “IPv4 address

How to find public IP address of your system?

Go to “google.com” & search “what is my ip” and press enter/search, it will display your public IP address.

NAT –Network Address Resolution

Network address translation (NAT) is a method of remapping an IP addresses in one network space into a single IP address.

Self-learning topics

IPv4 –32 bits & max addresses can be 4 billions. That’s why they created IPv6

IPv6

Static & Dynamic IP –Manual assignment & Automatic-assignment

Sub-netting –Divide a network into subnetwork for privacy and protection

TCP/IP and UDP –Important protocols in network

Reference books:

(Free book) An introduction to Computer Networks by Peter L Dordal.

http://intronetworks.cs.luc.edu/current2/ComputerNetworks.pdf

Data communication and network by Forouzon.

https://www.amazon.in/DATA-COMMUNICATIONS-NETWORKING-Behrouz-Forouzan/dp/0070634149

That's all for this module!

Click below to get to the Next Module - Basics of Computer Network

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-ELLIOT<Mr. Robot>

Disclaimer:

Usage of these information/Data/Tools/Techniques for attacking targets without prior mutual consent is illegal. It's the end user's responsibility to obey all applicable local, state and federal laws. The Computer Joker/Instructor/Owner assume no liability and are not responsible for any misuse or damage caused by this program. Only use for educational purpose. The Computer Joker/owner/Instructor do not support/promote hacking. For more details, head to our t&c page.

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