Chapter 4 (P72-75)Mohammed F & Aya

Peer-to-Peer Networks• Peer-to-peer network are usually common in

homes and small businesses and are not necessarily expensive.

• On a peer-to-peer network each computer shares their own files where other computers can access them with the correct permissions.

• An example would be that it has a similarity to Facebook although, the information saved onto the computers has no privacy and anybody can access it from any other computer.

• However, this method of sharing information can be illegal due to spreading copyrighted material, though they have many legitimate uses.

Firewalls• A Firewall is hardware or software that determines which data is allowed to

enter and leave the network. Firewalls are built into the computers / laptops or it can be built into network routers, firewalls can be installed on desktops those are referred as personal firewall.

• Firewalls are meant to help secure a computer by preventing any access from external unauthorised users, and to control which users and programs are allowed to connect to external network such as the internet. Firewalls can be arranged to allow or block traffic using a number of methods which are:

• IP addresses: Gives a unique number to each user on the computer. IP addresses of specific computers can be allowed or denied access.

• Domain names: access to particular web sites, such as social networks, can be blocked by specifying their name.

• Protocols & ports: There are different types of protocol’s such as HTTP, SMTP, POP3 and FTP these can be blocked or allowed. Either protocol or port can be blocked.

• Application program- Individual programs can be granted or denied network access.

Proxy Servers• They act as a middle step between two

computers. All communication between the two passes through the proxy, which allows it to perform a number of tasks including caching, filtering and logging data. Proxy servers are a common way to implement firewall functionality and record logs of users’ web activity.

• Caching: It is used to speed up activities such as web browsing. Proxy servers keep a copy of commonly requested material, such as web page, in a storage are called a cache.

Local Area Networks (LAN)• Provides networking capabilities to a group of

computers within close proximity.• Common places: Offices, Schools, Hospitals &

EVEN @ home.• Mostly LAN’s are connected together through

Ethernet cables to hubs & routers(expensive equipment).

• Advantages include, local email communication, easy file sharing & sharing of ISP.

• Disadvantages include, privacy of data shared over the network is under threat as it is going through the open before being received by the recipient. Virus threat as computers are not stand alone (if connected to the internet).

Components of a typical LAN

1. Servers: Many types of servers, most common is the file server providing the ability to save files on the network and can be accessed by any computer connected.

2. All Computers connected physically using an Ethernet cable to either a central server or a router/hub.

Wireless LAN (WLAN)• LAN format however access is granted through

wireless means, mostly wireless fidelity (Wi-Fi).• Almost all WLAN’s require authentication details

to be entered before access can be granted, mostly in the form of username & password.

• Not only wirelessly capable computers, but smartphones, PDA’s and tablets can also access the WLAN providing that the authentication is genuine.

• WLAN’s may also be provided for the public to access the internet at places called hotspots, i.e. coffee shops.

Personal Area Networks (PAN)• A computer network organized by connecting two

devices together, commonly using wireless means. For example connecting your phone to your computer using Bluetooth to browse the content stored is creating a PAN.

• PAN is most commonly used to transfer data/media between two devices, which is why the distance required to connect is very minimal.

• Most common example: Synchronising your Apple device with iTunes using both Wi-Fi or USB connections.

Metropolitan Area Networks (MAN) & Wide Area Networks (WAN)• MAN: A network covering a very large

area/campus, much like our very school. MAN is a series of LAN’s connected together which provides a time efficient solution of sharing information over great distances.

• Further LARGE connections are known as WAN’s, often used by business & banks across cities. For such large networks, the central hub/bridge is often a satellite which uses high frequency radio waves & microwaves to transmit the shared information from one branch to the other. Therefore it explains the antennae's on top of the office branches.

Storage Area Networks (SAN)• A network established to provide a non local place

to save your data. It appears as though it is a connected hard disk however is located & accessed remotely.

• Most commonly used in office LAN’s however using Apple’s Time Capsule, it is now available at home as well.Video Link

Virtual Private Networks (VPN)• WAN’s often communicate between each other

and the exchange of data needs to separately encrypted and sent in order to keep the data secure.

• VPN is a form of a secure tunnel which protects the flowing data from prying eyes. An example of using a VPN on personal basis includes protecting your web history whilst using a public network.

• Examples of VPN’s include Hotspot Shield & Spotflux.

Virtual LAN (VLAN)• Similar concept to VPN’s, geographically

separated computers or LAN’s are connected together rather than individual computers.

• It provides a better form or communication for businesses & companies located all across the country, or indeed, the globe.

ITGS Article• Time Capsule Issue VPN’s used to protect

browsing data at Starbucks