Network Security Concept

Network security is an important part of any network. It protects data when transmitting from one computer to another. Some terms related to network security are explained below:

Virus

A virus is a computer program that is made to harm our computer data, files, and other programs. Viruses can spread computers to computer and they can replicate themselves.

Antivirus

Antivirus is a computer program that used to find viruses in computers. Antivirus can disinfect virus-infected files and if it is not able to disinfect then it deleted the file. It is a very important program for every computer to make computers and networks more secure.

Spam

Spam is a mail or message that is sent to users without their approval. It can be sent by any organization to thousands or millions of people for promoting a particular product or service. It also can be a mail scam to get other people's money.

Cookies

A cookie is a small text file that any browser store to keep track of a user's activity on a specific website. It also used to identify the user or customize webpages according to the user's interests.

Firewall

A firewall is a network security device that monitors incoming and outgoing network traffic. It establishes a barrier between our internal network and incoming traffic from external sources (such as the internet) to block malicious traffic like viruses and hackers. A firewall can be either hardware and software.

HTTPS

HTTPS stands for HyperText Transfer Protocol Secure. It is a secure version of HTTP. It is a protocol for securing the communication between two systems e.g. the browser and the webserver. In HTTPS, the communication protocol is encrypted using Transport Layer Security (TLS) or, Secure Sockets Layer (SSL). 

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SIM  (Subscriber Identity Module)

 A sim is a tinny computer cheap card that gives a cellular device its unique phone number.  It contains all the credentials which important to connect to any cellular network. Current SIMs typically have 16 to 64 kb of memory which used for storing personal phone numbers, text messages, and other data.

SMS  (Short Message Service)

SMS is the transmission of short text messages to and from a mobile phone, fax machine, and other devices. The message must be no longer than some fixed number of alphanumeric characters and contain no images or graphics.

MMS  (Multimedia Message Service)

It is a standard messaging service to send multimedia content to and from any mobile phone over Cellular network. This includes images, videos, and sound files.

E-mail  (Electronic mail)

It allows you to send and receive messages to and from anyone with an email address anywhere in the world. Email address is a unique address for every user, required to receive and send emails. Photos documents and other files can be attached to an email so that more information can be shared.

Voicemail

A Voicemail system is a Computer Based system that allows users and subscribers to exchange personal voice messages.

Video Conferencing

A technology that allows users in different locations to hold face to face meetings without having to move to a single location.

Chat

Online textual talk in real-time is called chatting. In chatting we type a message on our screen, which is immediately received by the recipient then the recipient can type a message in response to our message which is received by us instantly.

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Wi-Fi

Wi-Fi is a wireless networking technology that allows computers to connect with the internet without using direct lines or cable from our PC to the Internet. For working of wi-fi we need-

1. Internet Connection
2. Wireless Router
3. Computers having a wireless network card.

Wi-Fi Hotspot

Wi-Fi is a venue or place that provides Wi-Fi access. These locations can be School campus, Restaurant, Library, Railay station, etc where the public can use a laptop, Mobile phone, or another suitable device to access Wi-Fi.

WiMax

WiMax is a wireless digital communication system. WiMax can provide broadband wireless access up to 30 miles (50 KM) for fixed stations. WiMax requires a  tower called base station similar to a cell phone tower. WiMax is more secure, can cover more area, and can provide more internet speed than a Wi-Fi.

VOIP

VOIP stands for Voice over Internet Protocol. VOIP provides phone services over the internet. It is more reliable and cheaper than traditional phone services.

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1G mobile system

The 1G mobile system is introduced in the early 1980s. The 1G mobile system was based on analog cellular Technology. This network was mainly designed for voice calls no consideration of Data Services. The major drawback of the 1G system were its low capacity, poor voice links and no security.

2G mobile system

The 2G network was the first digital cellular system introduced in 1990. The 2G system was based on GSM Technology. 2G was offering improved sound quality, better security, SMS, Voicemail and fax services.

2.5G mobile system

 It is the enhanced version of 2G. It offers services like MMS, sending pictures through email.

3G mobile system

3G Technology adds multimedia facilities to the 2G phone by allowing video, audio and graphics applications. With the invention of 3G watching online videos and video conferencing become a reality. It has the capacity of higher data rates and it opens the door to many internet style applications. The 3G mobile system is also known as the universal mobile telecommunication system (UMTS).

4G mobile system

4G is an enhanced version of 3G it is based on packet switching. It is able to support faster transmission. It provides data rate up to 100 MBPS. It is wireless access technology.

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Wireless Communication

Wireless communication means the method of transferring information between computing devices without using any physical connection. For example- when we try to access any agency database server from our mobile phone without using any physical connection. Not all wireless technologies are mobile technology.  In wireless communication device is continuously connected to the base network.

Mobile Communication

Mobile is a device that is portable. Mobile communication is based on a cellular network. A cellular network is nothing but a radio network. A mobile device may be a PDA, smartphone, laptop, and any other device that allows the user to complete computing tasks without connection with any other wireless network. In this communication, the device is not continuously connected to the base or central network.

Mobile Communication Technologies

GSM: GSM stands for a global system for mobile communication which is one of the leading digital cellular systems. The GSM standard for Digital cell phones was established in Europe in the mid 9080s. It becomes the International standard in Europe, Australia, and much of Asia and Africa. Cell phones users can buy one phone that will work anywhere where the standard is supported. To connect to the specific service providers in different countries, GSM users simply switch SIM cards. They stores all the connections and identification numbers to access a particular wireless service provider.

CDMA: CDMA stands for code division multiple access. CDMA is designed by Qualcomm in the United States. It is used second and third generation of the wireless communication. It is a digital cellular technology that uses spread spectrum techniques. Because of spread spectrum  is it it maintains high security and noise reduction. In this techniques several transmitters can send information simultaneously over a single communication channel.

Types of Computer Network

A computer network means a group of networked computers. A network can be a small group of linked computers or can be a large group. Thus networks vary in size and complexity.  There can be four types of networks on the basis of geographical spread.

1. Personal area network (PAN)
2. Local area network (LAN)
3. Metropolitan area network (MAN)
4. Wide area network (WAN)

Personal area network (PAN)

A personal area network organized around an individual person, typically within a 10-metre range. For example- a person has a laptop, mobile phone, PDA and any portable printer all are connected with a single Wi-Fi network.

Local area network (LAN)

A local area network is a computer network that interconnects computer within a limited area such as Residency, School, laboratory, University campus, or office building.  The key purpose of a LAN  is to serve its user in resource sharing. The hardware, as well as software resources, are shared through LANs.

Metropolitan area network (MAN)

Metropolitan Area Network is the networks spread over a city.  For example -  cable TV Network that is spread over a city. It is just a bigger version of LAN and normally uses similar Technology. MAN is also the sharing of hardware and software resources along with its user.

Wide area network (WAN)

The network spread across the large geographical area like countries are known as wide area networks. A wide area network is a group of LANs that are spread across several locations and connected together to look like one big LAN.  Wide area network link offers computer to exchange information at laser costs and higher speeds. The internet is the largest WAN,  spanning the entire Earth.

Network Devices

For the efficient working of any network, many devices are required. Some of them are discussed below:

Modem (Modulator-Demodulator)

A modem is a Peripheral device that enables a computer to transmit data over telephone or cable lines. Because ordinary telephone lines cannot carry digital information, a modem changes digital data from our computer into analog data, a format that can be carried by telephone lines. Similarly, when modem receiving data then it changes analog data back into digital data.

HUB

A Hub is a hardware device used to connect several computers together. Basically, Hubs are multislot concentrators in which a number of computers can be plugged to grow the size of the network.

Hub can be either active and passive

1. Active Hub: Active hubs Electrically amplify the signal as it moves from one connected device to another.
2. Passive Hub: Passive hub allow the signals to pass from one computer to another without any change.

Switch

A switch is a device that is used to break a network into different sub-networks or the LAN  segment, this prevents traffic overloading on the network. in simple terms,  a network switch is a small hardware device that joins multiple computers together within one Local area network. Network switches appear nearly identical to a network hub, but a switch generally contains more intelligence than a hub. We can say that a switch is an intelligent hub and is obviously more expensive than a hub.

Gateway 

Gateway is a device that connects dissimilar networks. It is capable of joining together two networks that use different base protocols. It establishes an intelligent connection between local networks and external networks with completely different structures.

Ethernet Card

Ethernet is a LAN architecture developed by Xerox Corporation. Ethernet uses a Bus or star topology and can support Data transfer rates of up to 10 Mbps. In computer for use of ethernet have to install a special type of card called Ethernet card.

Ethernet card is a kind of network adaptor and is also known as a network interface card (NIC). It supports high-speed network connections via cables. Newer internet cards are installed usually by the manufacturer inside the computers.

RJ-45 Connector

 RJ-45 stands for registered Jack 45. RJ-45 is an 8 wire connector that is used to connect computers on a local area network (LAN) especially Ethernet

Bridge

A bridge is a network device that can connect two local networks with the same standard but a different type of cable. Bridges are capable to know which computers are on which side of the bridge, so they only allow those messages that going to cross the bridge.

Router

A router is a network device that works like a bridge but can handle different protocols. In short, A router is a network device that can connect two networks with different protocols.

Repeater

When a signal travels along a cable, it tends to lose strength. A repeater is a device that regenerates a network's signal and rebroadcasts it.

Wi-Fi Card

Wi-Fi is also known as WNIC (Wireless Network Interface Card). This is an essential component for the use of wi-fi. Without a wi-fi card, any computer can not be able to access wi-fi.

Satellites are an essential part of the telecommunication system worldwide today. They can carry a large amount of data. satellite communication is a special use of microwave transmission systems. A Satellite is placed above the earth where its orbital speed exactly matches the Earth's rotation speed.  Hence it always stays over the same point with respect to the Earth.  In satellite communication, the earth station consists of a satellite dish that functions as an antenna and communication equipment to transmit and receive data from satellite overhead.

Advantages of Satellite Transmission

1. The area coverage through satellite transmission is quite large.

2. This is particularly useful for sparsely populated areas.

Disadvantages of Satellite Transmission

1. Placing the satellite into its Orbit involves a very high cost.
2. Transmission is affected by weather conditions like rain, thunderstorm, etc.

We are quite familiar with Radios and their working. Each radio signal uses a different frequency and this differentiates it from others. The transmitter takes some message, encodes it, and then transmit it with the radio wave. The receiver on the other end receives the radio waves and decodes it. Both the transmitter and receiver use antennas to radiate and capture the radio signal. Radio transmission is widely used by delivery services, policemen, security personals, etc.

Advantages of Radio Wave

1. It is easy to communicate through radio waves in difficult terrains since there is no need for any type of cable.
2. It can travel long distances in all directions. Also they can easily pass through obstacles like buildings so it can be used anywhere.

 Disadvantages of Radio Wave

1. Data Transmission is not secure.
2. The radio wave is susceptible to weather effects like rains, thunderstorms, etc.

Infrared is a type of unguided or wired transmission media. This is the frequency of light that is not visible to the human eye. Infrared light is widely used for short-range communication. The remote control is used in TV, VCR, Stereos, and other devices all use infrared communication.

Advantages of Infrared

1. It having short-range communication hence it is a secure mode of transmission.
2. It is quite an inexpensive transmission medium.

Disadvantages of Infrared

1. It can be only used in short-range transmission.
2. Infrared wave transmission cannot pass through obstruction like walls, buildings, etc.

Coaxial Cable

Coaxial cable is the most commonly used transmission media for LANs.  It consists of solid wire cores surrounded by one or more foil or wire shields, each separated by some kind of plastic insulator. The inner core carries the signal and the shield provides the ground. It has high electrical properties and is suitable for high-speed communication it is widely used for television signals and also in building security systems.

Coaxial Cable

Types of Coaxial Cable

1. Thicknet
2. Thinnet

Thicknet

Its cable segment can be up to 500 meters.

Thinnet

This is thinner than Thicknet. Its cable segment can be up to 185 meters.

Advantages of Coaxial Cable

1. Data transmission characteristics are better than twisted pair cable.

1.  It can be used for broadband communication.

2.  It can be used for a shared cable network.

3.  It offers a high bandwidth of up to 400 Mbps.

Disadvantages of Coaxial Cable

1. It is expensive compared to twisted pair cables.

2.  It is not compatible with twisted pair cable.

Twisted pair cable is one of the most common forms of wiring in networks, Especially in LANs and it consists of two insulated wires arranged in a regular spiral pattern (Double helix). It is generally used for telephone communications in offices and also in modern Ethernet networks. For telephonic communication a Voice Grade Medium (VGM) cable is used but for LAN applications a higher quality cable known as Data Grade Medium (DGM) is used.

Types of Twisted Pair Cable

There are two types of twisted pair cable:

1. Shielded Twisted pair cable (STP)
2. Unshielded Twisted pair cable (UTP)

Shielded Twisted Pair (STP) Cable

Unshielded Twisted Pair (UTP) Cable

Advantages of Twisted Pair Cable

1. It is simple.
2. It is physically flexible.
3. It is easy to install and maintain.
4. It can be easily Connected and has a low weight.
5. It is very inexpensive.

Disadvantages of Twisted Pair Cable

1. It can be easily pick up noise signals.
2. Being thin in size, it is likely to break easily.
3. It is unsuitable for broadband applications.

Transmission Media

Transmission media is a medium that carries a signal from one computer to another. It is also known as a communication channel. transmission media can be of two types:

1.  Guided Transmission Media (Wired Transmission Media)
2.  Unguided Transmission Media (Wireless Transmission Media)

Guided Transmission Media

This media physically connects the two or more computers. The data signal physically gets transferred from the source computer to the destination computer through the wired transmission medium.

Some of the Guided media are as follows: 

• Twisted pair cable
• Coaxial cable
• Optical Fiber

Unguided Transmission Media

Unguided or wireless transmission media transfer electromagnetic waves without using a physical conductor the signal is broadcasted through air or water.

Some of the Unguided media are as follows: 

• Infrared
• Radio Wave
• Microwave
• Satellite Link

Node, Server, and NIC

Node/Workstation

Node (workstation): A computer becomes a node when it attached to a network. If there are no notes there would be no network.

Server: a computer that facilitates the sharing of data, software, and hardware resources on the network is known as the server. A network can have more than one server. Each server has a unique name by which it is identified by all the nodes on the network.

Server

A server can be of two types:

1. Dedicated Server
2. Non-Dedicated Server

1) Dedicated Server: In Big networks, one computer is reserved for the server's job it helps all nodes to access data, software, and hardware resources. Since it does not double up as a workstation but only manages the network. So, it is known as dedicated server and such types of networks are called Master-Slave networks.

2) Non-Dedicated Server: In small networks, a workstation can double up as a server. These servers are known as Non-Dedicated Servers. Such types of networks are known as peer-to-peer networks.

Network Interface Unit (NIU)

 A Network Interface Unit (NIU) is a device that is attached to each of the nodes and the server which helps to establish communication between the server and node. Without this computers will not be able to perform the operation on network. The NIU basically acts as an interpreter and is also known as Terminal Access Point (TAP) or Network Interface Card (NIC). The manufacturer assign a unique physical address to each NIC and this physical address is known as the MAC address.

Switching Techniques means techniques from which data are transmitted across networks. The Three Types of switching techniques are employed to provide communication between two computers on a network are:

1. Circuit Switching 
2. Message Switching
3. Packet Switching

1) Circuit Switching 

circuit switching is a technique that directly connects the sender and the receiver in an unbroken path. With this type of technique, once a connection is established a dedicated path exists between both ends until the connection is terminated. For example, telephone switching equipment establishes a path that connects the caller's telephone to the receiver's telephone by making a physical connection. The important property of this switching technique is to an end-to-end path between computers Before any data can be sent.

2) Message Switching

In this technique, the source computer sends data for the message to the switching office first, which stores the data in its buffer. It then Looks for a free link to another switching office and then sends the data to this office. This process is continued until the data are delivered to the destination computers. This type of network is called a store and forward network.

3) Packet Switching

in the packet switching method, the message is broken into small parts, called packets. Each packet is tagged with appropriate source and destination addresses. Data packets can be stored in the main memory instead of the disc there for access delay and costs are minimized also the transmission speeds between nodes are optimized.

Networking Basics syllabus for 12th class (Science and Commerce) - JAC, CBSE, and State Boards 

Introduction: Network, Application of Network, Disadvantage of networking.

Evolution of Networking: ARPANET, Internet, Interspace, switching techniques
(Circuit, Message, and Packet switching), NIC.

Server: Node, Server, Types of server- Dedicated, Non-dedicated.

Data Communication terminologies: Concept of Channel, Bandwidth (Hz,
KHz, and MHz) and Data transfer rate (bps, Kbps, Mbps, Gbps, Tbps), Baud.

Transmission media: Guided, Unguided, Twisted pair cable, coaxial cable,
optical fiber, infrared, radio link, microwave link, and satellite link.

Network devices: Modem, Hub, RJ45 connector, Ethernet Card, Router, Switch,
Gateway, Repeater, Wi-Fi card.

Network Topologies and types: Point to Point Link, Bus, Star, Tree, Mesh,
Ring, Graph, PAN, LAN, WAN, MAN.

Network Protocol: HTTP, TCP/IP, File Transfer Protocol (FTP), PPP, SMTP,
Remote Login (Telnet), and Internet Wireless/Mobile Communication protocol such
as GSM, CDMA, GPRS, and WLL.

Mobile Telecommunication Technologies: 1G, 2G, 3G and 4G, VOIP, WiFi, and WiMax;
SIM, SMS, MMS, E-mail, Voicemail, Video conferencing, Chat.

Network Security Concepts: Viruses, Antiviruses, Spams, Use of Cookies,
Protection using Firewall, https;
India IT Act, Cyber Law, Cyber Crimes, IPR issues, hacking.

Introduction to Web services: WWW, HTML, XML;
Domain Names, URL, Website, Web browser, Web Servers, Web Hosting; 

  

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Evolution of networking

The evolution of networking has started way back in 1969 by the development of ARPANET, which was the first to the development of the Internet.

ARPANET

In 1969, the world's first network was developed and networking was started with the development of ARPANET. The US Department of Defense sponsored a project named ARPANET (Advanced Research Projects Agency Network) whose goal was to connect computers at different universities and US Defence. Soon the engineers, Scientists, Students, and Researchers who were also able to play long-distance games and socialize with people who share their interests.

In the mid-1980s another federal agency, the national science foundation created a new high capacity network called NSFnet (National Science Foundation Network) which was more capable than ARPANET. NSFnet allowed only the academic research on its network and not any private business on it. So, many private companies built their own networks, which were later interconnected along with ARPANET and NSFnet to form the Internet.

ARPANET was shut down in 1990 and NSFnet was shut down in 1995.

Internet

The Internet is a worldwide network of computer networks that developed from the first network ARPANET. The internet is made up of many small networks each run by different companies. and interconnected at the peering point (Point where two networks connect or exchange data). It is an interconnection of large and small networks around the globe. The Internet allows users to communicate with another user which is connected to another network. 

The internet is a supernetwork it allows all the computers to exchange information with each other. Internet uses a common set of rules to communicate which are called Protocols and the internet uses a set of protocols called TCP/IP (Transmission Control Protocol / Internet Protocol). 

Interspace

Interspace is a client/server software program that allows multiple users to communicate online with real-time audio, video, and text chat in dynamic 3D environments.

an interspace is an advanced form of the internet where users communicate in multiple ways from multiple sources.

Introduction of Computer Network.

When two or more computers linked together for the purpose of sharing (sending/receiving) data and information, known as Computer Network.

Computer Network

Network Goals and Applications

• Resource Sharing: The hardware devices like printers and scanners can be shared over a Network. This reduces costs by reducing the number of hardware items.
• Storage Sharing: On a network, the user can access the data of another machine and can store data on another machine.
• Reliability: A file can have copies on two or three different computers. So, if one is not available other copies can be used.
• Access to a remote database: User can access the Host computer at his PC and send the request. For example - users can make flight reservations, book hotels, and so on anywhere in the world with instant confirmation.
• Communication Facilities: Network provides us facilities to communicate with others via Emails, Chats, Video conferencing, and so on.

Disadvantages of Networking

• Complex: Systems are more complex to run.
• Server fails: If all data are held centrally in a server. It may create problems if the central server fails.
• Expensive to install: Cables, Network devices, NIC, and Softwares required for installation of the network. And these are quite expensive.

We all know what Network is and what it can do. But the problem is how can we link computers to make a network? What structure should we follow to making a network? The solution to all these problems is Topology. Today in this blog we will know about Topology.

Network Topology

Before going deep in Topology we should know about Point-to-Point Link first.

point to point link-point to point link has two ends transmitter and receiver. the main characteristic of point to point link is that each transmitter transmits data to exactly one receiver and each receiver receives data from exactly one transmitter. In other words, we can say that it is two computer's link in which each computer can send or receive data directly from each other without any interruption of other computers.

Point to Point Link

The pattern in which computers/Nodes linked with a network known as Topology. Topology can be of 6 types-

• Bus Topology
• Star Topology
• Mesh Topology
• Ring Topology
• Tree Topology
• Graph Topology

You can also watch this video to know about Topology.

Let's explain all of this one by one 

Bus Topology:  Bus Topology is also known as Linear Topology. In this type of Topology each node attaches directly to a common cable which is known as the 'Backbone Network' when any computer wants to send data, all computers on the network receive the information but only one accepts the information. In this Topology, cable termination is required cable cannot be left unterminated.

Bus Topology

Advantages:

• Reliable, easy to use, and easy to install.
• Additional nodes can easily connect to the existing network at any point.

Disadvantages:

• Fault detection and isolation is difficult.
• In any case, the failure of the Backbone Network can affect all devices in the network. 

Star Topology: A Star Topology consists of devices connected by Point to Point link to a central Hub or Server. 1t

is easy to control and traffic flow is simple. Dala travels from the sender to the central hub and then to the receiver.

Advantages:

• Single connection failure does not affect the entire network.
• Fault detection is easier
• It is easy to add a new node without disturbing the entire network.

Disadvantages:

• If central Hub fails, the whole network fails.
• Needed a large number of cables so, it increases installation charges.

Mesh Topology: In this Topology each node in network creating Point to Point link with all nodes.

Advantages:

• Single connection failure does not affect the entire network.
• Fault detection is easier
• Every computer has multiple ways to transfer or receive data.

Disadvantages:

• Difficult to add a new node.
• Needed a large number of cables so, it increases installation charges.

Ring Topology: In this Topology, each node directly connected to two or only two neighbor computers. Data travels node to node only in one direction around the circle. That's why this Topology is also known as Circular Topology.

Advantages:

• Reliable, easy to use, and easy to install.
• Additional nodes can easily connect to the existing network at any point.
• Less expensive

Disadvantages:

• Fault detection and isolation is difficult.
• The failure of any node of the network can affect all devices in the network. 

Tree Topology: This topology makes a tree in its structure that's why it is known as Tree Topology. This is a combination of Bus and Star topology. Many hubs directly connected to the Bus and computers directly connected to the hubs.

Advantages:

• Error detection and correction is easy.
• Additional nodes can be added easily.

Disadvantages:

• When many segments added, Maintenance becomes difficult.
• The failure of the backbone network can affect all devices in the network. 

Graph Topology: This Topology is a mixture of all topologies. In this topology, every node has many ways to send data to the other computers.