it presentation on networking

8/3/2019 It Presentation on Networking

1/54

NetworkingNetworkingSubmitted By :Submitted By :--

RohitRohit SinghSingh

AnujAnuj GeraGera

SagarSagar KauraKaura

BhumikaBhumika SachdevaSachdeva

KhushbooKhushboo KanodiaKanodia


2/54

What is a Network?What is a Network?

A network isA network is two or more computerstwo or more computers, or other, or otherelectronic devices,electronic devices,connectedconnected together so that they cantogether so that they canexchange dataexchange data..

For example a network allows computers toFor example a network allows computers to sharesharefilesfiles, users to, users to messagemessage each other, a whole room ofeach other, a whole room ofcomputers tocomputers to share a single printershare a single printer, etc., etc.

Network connections between computers are typicallyNetwork connections between computers are typicallycreated usingcreated usingcablescables (wires). However, connections can(wires). However, connections can

be created usingbe created usingradio signalsradio signals (wireless / wi(wireless / wi--fi),fi),telephone linestelephone lines (and modems) or even, for very long(and modems) or even, for very longdistances, viadistances, via satellitesatellite links.links.


3/54


4/54

Why Use Networks?Why Use Networks?

Using a computer connected to aUsing a computer connected to anetwork allows us tonetwork allows us to

EasilyEasilyshare filesshare files and dataand data

Share resourcesShare resources such as printerssuch as printersand Internet connectionsand Internet connections

CommunicateCommunicatewith other networkwith other networkusers (eusers (e--mail, instant messaging,mail, instant messaging,

videovideo--conferencing, etc.)conferencing, etc.)

Store data centrallyStore data centrally (using a file(using a fileserver) for ease of access and backserver) for ease of access and back--upup


5/54

In particular, if we use a computerIn particular, if we use a computer

connected to The Internet, weconnected to The Internet, wecancan

Make use ofMake use ofonon--line servicesline services suchsuchasas shoppingshopping (e(e--commerce) orcommerce) or

bankingbanking Get access to a huge range ofGet access to a huge range of

informationinformation for researchfor research

Access different forms ofAccess different forms of

entertainmententertainment (games, video, etc.)(games, video, etc.)

JoinJoin onon--line communitiesline communities (e.g.(e.g.MySpace,Facebook, etc.)MySpace,Facebook, etc.)


6/54

Why Not Use Networks?Why Not Use Networks?

Using a computer connected toUsing a computer connected toa network means thata network means that

The computer is vulnerable toThe computer is vulnerable to

hackershackers If theIf the network breaksnetwork breaks, many, many

tasks become very difficulttasks become very difficult

Your computer can more easilyYour computer can more easilybe attacked by abe attacked by avirusvirus


7/54

In particular, if we use a computer connected toIn particular, if we use a computer connected toThe InternetThe Internet

We have to be careful aboutWe have to be careful about revealing personalrevealing personal

informationinformation We have to be careful toWe have to be careful to avoid suspect websitesavoid suspect websites

that might containthat might contain malwaresmalwares

We have to be aware thatWe have to be aware that informationinformation found onfound on

The Internet isThe Internet is not always accurate or reliablenot always accurate or reliable


8/54

Computers in a NetworkComputers in a Network

Computers connected together to create aComputers connected together to create a

network fall into two categories:network fall into two categories: serversservers andandclientsclients (workstations).(workstations).

ClientsClients

Client computers, or workstations, are the normalClient computers, or workstations, are the normalcomputers that people sit at to get their work done.computers that people sit at to get their work done.


9/54

ServersServers

Servers are special, powerfulServers are special, powerfulcomputers that provide computers that provide servicesservices to tothethe clientclient computers on thecomputers on thenetwork.network.

These services might include:These services might include: Providing a central, common fileProviding a central, common file

storage areastorage area

Sharing hardware such as printersSharing hardware such as printers

Controlling who can or cant haveControlling who can or cant have

access the networkaccess the network Sharing Internet connectionsSharing Internet connections


10/54

Servers are built to be very reliable. This meansServers are built to be very reliable. This means

that they are much more expensive that normalthat they are much more expensive that normalcomputers.computers.

In a small network one server might provide all ofIn a small network one server might provide all of

these services. In a larger network there might bethese services. In a larger network there might be

many servers sharing the work.many servers sharing the work.


11/54

Types of NetworkTypes of Network


12/54

Local Area Network(LAN)Local Area Network(LAN)

A Local Area Network is aA Local Area Network is anetwork confined to onenetwork confined to onebuilding or site. Often a LANbuilding or site. Often a LANis a private network belongingis a private network belonging

to an organization orto an organization orbusiness.business.

Because LANs areBecause LANs aregeographically small, theygeographically small, they

usually use cables or lowusually use cables or low--power radio (wireless) for thepower radio (wireless) for theconnections.connections.


13/54

Wireless Local Area Network(WLAN)Wireless Local Area Network(WLAN)

A wireless LAN (WLAN) is a LAN that usesA wireless LAN (WLAN) is a LAN that uses radioradiosignalssignals ((WiFiWiFi) to connect computers instead of cables.) to connect computers instead of cables.

At the centre of the WLAN is aAt the centre of the WLAN is awireless switch orwireless switch or

routerrouter -- a small box with one or two antennas stickinga small box with one or two antennas stickingout the backout the back -- used forused for sending and receiving datasending and receiving data totothe computers. (Most laptops have a wireless antennathe computers. (Most laptops have a wireless antennabuilt into the case.)built into the case.)

It is much moreIt is much more convenientconvenient to use wirelessto use wirelessconnections instead of running long wires all over aconnections instead of running long wires all over abuilding.building.


14/54

However,WLANs are more difficult to make secureHowever,WLANs are more difficult to make securesince other people can also try to connect to thesince other people can also try to connect to thewireless network. So, it is very important to have awireless network. So, it is very important to have agood, hardgood, hard--toto--guess password for the WLANguess password for theWLANconnections.connections.


15/54

Wide Area Network(WAN)Wide Area Network(WAN)

A Wide Area Network is aA Wide Area Network is anetwork that extends overnetwork that extends overaa large arealarge area..

A WAN is often createdA WAN is often createdbybyjoining several LANsjoining several LANstogether, such as when atogether, such as when a

business that has offices inbusiness that has offices indifferent countries linksdifferent countries linksthe office LANs together.the office LANs together.


16/54

BecauseWANs are often geographically spread overBecauseWANs are often geographically spread overlarge areas andlarge areas and linkslinks between computers are overbetween computers are over longlong

distancesdistances, they often use quite exotic connections, they often use quite exotic connectionstechnologies:technologies: optical fibreoptical fibre (glass) cables,(glass) cables,satellitesatellite radioradiolinks,links,microwavemicrowave radio links, etc.radio links, etc.


17/54

Bluetooth (Personal Area Network)Bluetooth (Personal Area Network)

Bluetooth is a wireless networking technology designedBluetooth is a wireless networking technology designedfor veryfor veryshortshort--rangerange connections (typically just a fewconnections (typically just a fewmeteres).meteres).

The idea of Bluetooth is to get rid of the need for all ofThe idea of Bluetooth is to get rid of the need for all ofthose cables (e.g. USB cables) that connect ourthose cables (e.g. USB cables) that connect ourcomputer to peripheral devices such as printers, mice,computer to peripheral devices such as printers, mice,keyboards, etc.keyboards, etc.

Bluetooth devices contain small,Bluetooth devices contain small, lowlow--powerpower radioradiotransmitters and receivers. When devices are in range oftransmitters and receivers. When devices are in range ofother Bluetooth devices, they detect each other and canother Bluetooth devices, they detect each other and canbe 'be 'pairedpaired' (connected)' (connected)


18/54

Typical uses of Bluetooth:Typical uses of Bluetooth: Connecting aConnecting awireless keyboardwireless keyboard

to a computerto a computer

Connecting aConnecting awireless mousewireless mouse totoa computera computer

Using aUsing awireless headsetwireless headsetwith awith a

mobile phonemobile phone Printing wirelesslyPrinting wirelessly from afrom a

computer or PDAcomputer or PDA

Transferring dataTransferring data / music from/ music froma computer to an MPa computer to an MP33 playerplayer

Transferring photosTransferring photos from afrom aphone / camera to another devicephone / camera to another device

SynchronizingSynchronizing calendars on acalendars on aPDA and a computerPDA and a computer


19/54

Network TopologiesNetwork Topologies

The word topology means arrangement, soThe word topology means arrangement, so

when we talk about the topology of a network,when we talk about the topology of a network,

we mean how the different parts are arrangedwe mean how the different parts are arranged

and connected together.and connected together.There are three common network topologies...There are three common network topologies...

Bus NetworkBus Network

Ring NetworkRing Network Star NetworkStar Network


20/54

Bus NetworkBus Network

In this type of network, a long, central cable, the bus isIn this type of network, a long, central cable, the bus isused to connect all of the computers together. Eachused to connect all of the computers together. Eachcomputer has a short cable linking it to the bus.computer has a short cable linking it to the bus.

A bus networkA bus network IsIs cheap to installcheap to install (just one long cable)(just one long cable)

Can beCan be quite slowquite slowsince all computers share the same cablesince all computers share the same cablewhen communicatingwhen communicating

WillWill stopstopworking if there is aworking if there is a breakbreakin the central busin the central bus cablecable..


21/54


22/54

Ring NetworkRing Network

In this type of network each computer is connected toIn this type of network each computer is connected toa loop of cable, the ring. (If you took a bus networka loop of cable, the ring. (If you took a bus networkand connected the ends of the bus cable together, youand connected the ends of the bus cable together, you

would have a ring network.)would have a ring network.) A ring networkA ring network

CanCan copecopewith awith a breakbreakin the ring cable since all computersin the ring cable since all computersare still joined together (it is now a bus network)are still joined together (it is now a bus network)


23/54


24/54

Star NetworkStar Network

In this type of network every computer is connected to aIn this type of network every computer is connected to a centralcentraldevicedevice. The device. The devicepasses messagespasses messages between computers.between computers.

At the centre of a star network you might use aAt the centre of a star network you might use a hubhub (cheap, but(cheap, butslower) or aslower) or a switchswitch (more expensive, but faster).(more expensive, but faster).

A star networkA star network

IsIs quite expensivequite expensive to install (you have to buyto install (you have to buylots of cablelots of cable and theand thecentral devicecentral device))

IsIsvery fastvery fast since each computer has its own cable which it doesnt needsince each computer has its own cable which it doesnt needto shareto share

CanCan copecopewith awith a broken cablebroken cable (only one computer will be affected)(only one computer will be affected)

WillWill stopstopworking if the centralworking if the central device breaksdevice breaks Is the mostIs the most commoncommon network topologynetwork topology


25/54


26/54

Hybrid NetworkHybrid Network

A hybrid network is simply one thatA hybrid network is simply one that combinescombinestwo or moretwo or more of the aboveof the above basic topologiesbasic topologies..

E.g. A network that hasE.g. A network that has several star networksseveral star networks

linked togetherlinked together is a hybrid networkis a hybrid network


27/54


28/54

Networking Hardware


29/54

Network Interface Card (NIC)Network Interface Card (NIC)

Any computer that is to beAny computer that is to beconnected to a network,connected to a network,needs to have a networkneeds to have a networkinterface card (NIC).interface card (NIC).

Most modern computersMost modern computershave these devices built intohave these devices built intothe motherboard, but inthe motherboard, but insome computers you havesome computers you have

to add an extra expansionto add an extra expansioncard (small circuitboard)card (small circuitboard)


30/54

NetworkCableNetworkCable

To connect together differentTo connect together differentdevices to make up a network,devices to make up a network,you need cables.you need cables.

CablesCables are still used in mostare still used in most

networks, rather than usingnetworks, rather than usingonly wireless, because they canonly wireless, because they cancarry much morecarry much more data perdata persecondsecond, and are more, and are more securesecure(less open to hacking).(less open to hacking).


31/54

HubHub

A hub is a device thatA hub is a device that connectsconnects a number ofa number ofcomputers together to make acomputers together to make a LANLAN..

The typical use of a hub is at theThe typical use of a hub is at the centre of a starcentre of a starnetworknetwork(or as part of a hybrid network)(or as part of a hybrid network) -- the hub hasthe hub hascables plugged into it from each computer.cables plugged into it from each computer.

A hub is a dumb device: if it receives a message, itA hub is a dumb device: if it receives a message, itsends it to every computer on the network. This meanssends it to every computer on the network. This means

that hubthat hub--based networks are not very securebased networks are not very secure -- everyoneeveryonecan listen in to communications.can listen in to communications.


32/54


33/54

SwitchSwitch

A switch, like a hub, is a device thatA switch, like a hub, is a device that connectsconnects aanumber of computers together to make anumber of computers together to make a LANLAN..

The typical use of a switch is at theThe typical use of a switch is at the centre of a starcentre of a starnetworknetwork(or as part of a hybrid network)(or as part of a hybrid network) -- the switchthe switchhas cables plugged into it from each computer.has cables plugged into it from each computer.

A switch is a more A switch is a more intelligentintelligent device than a hub: if it device than a hub: if itreceives a message, it checks who it isreceives a message, it checks who it is addressedaddressed to,to,

and only sends it to thatand only sends it to that specific computerspecific computer. Because. Becauseof this, networks that use switches areof this, networks that use switches are more securemore securethan those that use hubs, but also a little morethan those that use hubs, but also a little moreexpensiveexpensive..


34/54


35/54

RouterRouter

A router is a network device thatA router is a network device that connectsconnects togethertogethertwo or more networkstwo or more networks..

A common use of a router is toA common use of a router is to joinjoin a home ora home orbusiness network(business network(LANLAN) to the) to the InternetInternet (WAN).(WAN).

The router will typically have the Internet cable pluggedThe router will typically have the Internet cable pluggedinto it, as well as a cable, or cables to computers on theinto it, as well as a cable, or cables to computers on theLAN.LAN.

Alternatively, the LAN connection might be wirelessAlternatively, the LAN connection might be wireless

(WiFi), making the device a wireless router. (A wireless(WiFi), making the device a wireless router. (A wirelessrouter is actually a router and wireless switchrouter is actually a router and wireless switchcombined)combined)


36/54


37/54

Proxy ServerProxy Server

A proxy server is a computer setup toA proxy server is a computer setup to share ashare aresourceresource, usually an, usually an Internet connectionInternet connection..

Other computers can request a web page via the proxyOther computers can request a web page via the proxyserver. The proxy server will then get the page using itsserver. The proxy server will then get the page using itsInternet connection, and pass it back to the computerInternet connection, and pass it back to the computerwho asked for it.who asked for it.

Proxy servers are often used instead of router sinceProxy servers are often used instead of router since

additional softwareadditional software can be easily installed on thecan be easily installed on thecomputer such as anticomputer such as anti--virus, web filtering etc.virus, web filtering etc.


38/54


39/54

BridgeBridge

A bridge is a network device that typically links togetherA bridge is a network device that typically links togethertwo different parts of a LAN.two different parts of a LAN.

Whereas a router is usually used to link a LAN to aWhereas a router is usually used to link a LAN to a

WAN (such as the Internet), a bridge links independentWAN (such as the Internet), a bridge links independentparts of a LAN so that they act as a single LAN.parts of a LAN so that they act as a single LAN.


40/54

FirewallFirewall

A firewall is aA firewall is a devicedevice, or a, or apiece ofpiece ofsoftwaresoftware that isthat isplaced between yourplaced between yourcomputer and the rest of thecomputer and the rest of thenetwork(where the hackersnetwork(where the hackers

are!)are!) If you wish toIf you wish toprotectprotect youryour

whole LAN fromwhole LAN from hackershackersout on the Internet, youout on the Internet, youwould place a firewallwould place a firewallbetween the LAN and thebetween the LAN and theInternet connectionInternet connection..


41/54

A firewallA firewall blocks unauthorized connectionsblocks unauthorized connections being made tobeing made toyour computer or LAN. Normal data is allowed through theyour computer or LAN. Normal data is allowed through thefirewall (e.g. efirewall (e.g. e--mails or web pages) but all other data is blockedmails or web pages) but all other data is blocked..


42/54

ModemModem

Before the days ofBefore the days ofbroadband Internetbroadband Internetconnections, most computersconnections, most computersconnected to the Internet viaconnected to the Internet viatelephone linestelephone lines ((dialdial--upup

connections).connections). The problem with usingThe problem with using

telephone lines is that theytelephone lines is that theyare designed to carryare designed to carryvoicesvoices,,which arewhich are analogueanalogue signals.signals.

They areThey are notnot designed fordesigned fordigital datadigital data..


43/54

The solution was to use a special device to join theThe solution was to use a special device to join thedigital computer to the analogue telephone line. Thisdigital computer to the analogue telephone line. This

device is known as a modem.device is known as a modem. A modem contains a DAC and an ADC.A modem contains a DAC and an ADC.

The DAC in the modem is required so that the digitalThe DAC in the modem is required so that the digitalcomputer can send data down the analogue telephonecomputer can send data down the analogue telephoneline (it converts digital data intoline (it converts digital data into noisesnoiseswhich is exactlywhich is exactlywhat the telephone line is designed to carry.)what the telephone line is designed to carry.)

The ADC in the modem is required so that the analogueThe ADC in the modem is required so that the analogue

signals (noises) that arrive via the telephone line can besignals (noises) that arrive via the telephone line can beconverted back into digital data.converted back into digital data.


44/54

So, simply put, a modem is required because computersSo, simply put, a modem is required because computersare digital devices and the telephone system is analogue.are digital devices and the telephone system is analogue.The modem converts from digital to analogue and fromThe modem converts from digital to analogue and from

analogue to digital.analogue to digital.


45/54

The InternetThe Internet

The Internet is a worldThe Internet is a world--widewidenetwork that has grown andnetwork that has grown andevolved from an experimentalevolved from an experimentalnetwork(ARPANet) created bynetwork(ARPANet) created by

the US military back in thethe US military back in the19601960s. Over the years, as mores. Over the years, as moreand more computers andand more computers andnetworks have connected to thisnetworks have connected to thisnetwork, it has grown into thenetwork, it has grown into the

Internet that we know today.Internet that we know today.


46/54

nn The Internet connects millions of people, andThe Internet connects millions of people, and

thousands of businesses, governments, schools,thousands of businesses, governments, schools,universities and other organizations.universities and other organizations.


47/54

What Can We Use the Internet For?What Can We Use the Internet For?

The Internet provides the network connections thatThe Internet provides the network connections thatlinks computers together. There are many ways that welinks computers together. There are many ways that wecan use these connections:can use these connections:

ViewViewweb pagesweb pages on the WWW(Worldon the WWW(World--WideWeb)WideWeb) Sending and receivingSending and receivingee--mailmail messagesmessages

Sharing filesSharing files

Communicating usingCommunicating usingvoicevoice (VOIP) and(VOIP) andvideovideo (video(video--

conferencing)conferencing) PlayingPlayingmultimulti--player gamesplayer games

Listening toListening to streamed musicstreamed music or watchingor watchingstreamed videostreamed video


48/54

IntranetsIntranets

An intranet is the name givenAn intranet is the name givento ato aprivate networkprivate networkthatthatprovidesprovides similar servicessimilar services totoThe Internet: eThe Internet: e--mail,mail,messaging, web pages, etc.messaging, web pages, etc.

However, these services areHowever, these services areonly for the users of theonly for the users of theintranetintranet they arethey areprivateprivate, not, notpublic (unlike Internet servicespublic (unlike Internet services

which are generally public).which are generally public).


49/54

BusinessesBusinesses and other organizations often haveand other organizations often have

intranets for use by theirintranets for use by their employeesemployees..

Typical uses of an intranet would be:Typical uses of an intranet would be:

ViewingViewinginternal web pagesinternal web pages (e.g. company(e.g. companycalendars, etc.)calendars, etc.)

Internal eInternal e--mailmail andand instantinstant--messagingmessaging betweenbetweenworkersworkers

Sharing of internal documentsSharing of internal documents


50/54

Setting Up a Small NetworkSetting Up a Small Network

If you were asked to build a small, InternetIf you were asked to build a small, Internet--connected networkconnected networkfrom scratch, what would you need to do?from scratch, what would you need to do?

You would need to buy some hardware:You would need to buy some hardware: One or moreOne or more switchesswitches // hubshubs -- to link devices togetherto link devices together

NetworkNetworkcablescables to connect devices to the switch, etc.to connect devices to the switch, etc.

A separateA separatewireless access pointwireless access point (or this could be part of the switch)(or this could be part of the switch) --to allow wireless devices (e.g. laptops or smartto allow wireless devices (e.g. laptops or smart--phones) to join thephones) to join thenetworknetwork

AA routerrouter to connect your LAN to the Internet (WAN)to connect your LAN to the Internet (WAN)

AA firewallfirewall to protect your network from hackersto protect your network from hackers

Possibly aPossibly a bridgebridge if you already have a section of network and you wantif you already have a section of network and you wantyour new network to connect to ityour new network to connect to it

Server(s)Server(s) to manage network functions such as networkto manage network functions such as networksecuritysecurity,,network filenetwork file storagestorage, shared, shared resourcesresources (such as printers)(such as printers)


51/54

You would need to organize some other things:You would need to organize some other things:

Set up anSet up an account with an Internet Serviceaccount with an Internet ServiceProvider (ISP)Provider (ISP)

Get anGet an Internet connectionInternet connection installed from the ISPinstalled from the ISPto your locationto your location

ConfigureConfigurevarious bits ofvarious bits ofhardwarehardware andand softwaresoftwareso that everything worked with the networkso that everything worked with the network


52/54


53/54

Network & Data SecurityNetwork & Data Security

As soon as your computer is connected toAs soon as your computer is connected toa network, you have to start thinkinga network, you have to start thinkingaboutabout securitysecurity security of your files,security of your files,information, etc.information, etc.

A network allows a person who does toA network allows a person who does to

have physical access to your computerhave physical access to your computer(they are not sitting in front of it) to(they are not sitting in front of it) to gaingainaccessaccess all the same. If your computer isall the same. If your computer isconnected to a network, other people canconnected to a network, other people canconnect to your computer.connect to your computer.

A person who gains unauthorised accessA person who gains unauthorised accessto a computer system is often called ato a computer system is often called ahackerhacker..


54/54

Preventing Unauthorized AccessPreventing Unauthorized Access

There are a number of security measures thatThere are a number of security measures thatyou can take to prevent hackers accessing youryou can take to prevent hackers accessing your

computer and all of the data stored on it:computer and all of the data stored on it:

Physical SecurityPhysical Security

it presentation on networking

Documents