Networks and the effects of using them
What is a network?
A network is two or more computers, or other electronic devices, connected together so that they can exchange data.
Different types of network computers.
There are 2 types of network computers:
Servers are special, powerful computers that provide ‘services’ to the client computers on the network.
Different types of Network
LAN (Local Area Network)
WLAN (Wireless Local Area Network)
A wireless LAN (WLAN) is a LAN that uses radio signals (WiFi) to connect computers instead of cables.
WAN (Wide Area Network
A Wide Area Network is a network that extends over a large area.
Bluetooth (WPAN) Wireless Personal Network
Bluetooth is a wireless networking technology designed for very short-range connections (typically just a few metres).
Typical uses of Bluetooth:
Connecting a wireless keyboard to a computer
Connecting a wireless mouse to a computer
Using a wireless headset with a mobile phone
Printing wirelessly from a computer.
Transferring data / music from a computer to an MP3 player
Transferring photos from a phone / camera to another device
Because Bluetooth networking only works over very short distances, and with devices belonging to one user, this type of network is sometimes called a 'Personal Area Network'
What is a router?
A router is used to enable data to be sent (routed) between different types of network. For example a between a
LAN (Local Area Network)
WAN. (Wide Area Network)
Is is the most common use as they are used to connect to the internet.
They connect through cables or wireless.
What does a router do?
What is an IP address?
An IP address, or simply an "IP," is a unique address that identifies a device on the Internet or a local network.
It allows a system to be recognized by other systems connected via the Internet protocol.
How does the router store these IP address?
Routers store IP addresses in a routing table
A packet of data can pass through many networks to get to its final destination
Network Interface Card (NIC)
Any computer that is to be connected to a network, needs to have a network interface card (NIC).
A hub is a device that connects a number of computers together to make a LAN.
A switch, like a hub, is a device that connects a number of computers together to make a LAN.
The typical use of a switch is at the centre of a star network (or as part of a hybrid network) - the switch has cables plugged into it from each computer.
A switch is a more ‘intelligent’ device than a hub: if it receives a message, it checks who it is addressed to, and only sends it to that specific computer. Because of this, networks that use switches are more secure than those that use hubs, but also a little more expensive.
How do switches work?
Each network device has a MAC address (Media Access Control). This is used to identify the device on the network.
Data sent to the switch contains both the sending MAC address and the receiving address.
The switch will check the address and only send to the correct device.
Because the switch only sends to the correct address it reduces the amount of network traffic and increases the network speed.
A bridge is a network device that typically links together two different parts of a LAN.
Whereas a router is usually used to link a LAN to a WAN (such as the Internet), a bridge links independent parts of a LAN so that they act as a single LAN.
Before the days of broadband Internet connections, most computers connected to the Internet via telephone lines (dial-up connections).
Analogue to Digital Convertor (ADC)
Digital to Analogue Convertor (DAC)
The DAC in the modem is required so that the digital computer can send data down the analogue telephone line (it converts digital data into noises which is exactly what the telephone line is designed to carry.)
The ADC in the modem is required so that the analogue signals (noises) that arrive via the telephone line can be converted back into digital data.
So, simply put, a modem is required because computers are digital devices and the telephone system is analogue. The modem converts from digital to analogue and from analogue to digital.
What is the Internet?
The Internet, sometimes called simply "the Net," is a worldwide system of computer networks -- a network of networks in which users at any one computer can, if they have permission, get information from any other computer
The Internet provides the network connections that links computers together.
There are many ways that we can use these connections:
View web pages on the WWW (World-Wide Web)
Sending and receiving e-mail messages
Sharing files Communicating using voice (VOIP) and video (video-conferencing)
Playing multi-player games
Listening to streamed music or watching streamed video
What is an Intranet?
An intranet is the name given to a private network that provides similar services to The Internet: e-mail, messaging, web pages, etc.
However, these services are only for the users of the intranet – they are private, not public (unlike Internet services which are generally public).
Businesses and other organisations often have intranets for use by their employees.
Typical uses of an intranet would be:
Viewing internal web pages (e.g. company calendars, etc.)
Internal e-mail and instant-messaging between workers
Sharing of internal documents
Compare Internet & Intranet
What is a firewall?
Connecting to the internet
There are 4 main devices commonly used to connect to the internet. See below the advantages and disadvantages of each.
Download and complete this activity sheet and then upload to your Weebly
Wi-Fi is the name of a popular wireless networking technology that uses radio waves to provide wireless high-speed Internet and network connections.
Bluetooth is a short-range wireless communication technology that allows devices such as mobile phones, computers, and peripherals to transmit data or voice wirelessly over a short distance. The purpose of Bluetooth is to replace the cables that normally connect devices, while still keeping the communications between them secure.
Compare Wifi and Bluetooth
How to setup and configure a small network
If you were asked to build a small, Internet-connected network from scratch, what would you need to do?
You would need to buy some hardware:
One or more switches / hubs - to link devices together
Network cables to connect devices to the switch, etc.
A separate wireless access point (or this could be part of the switch) - to allow wireless devices (e.g. laptops or smart-phones) to join the network
A router to connect your LAN to the Internet (WAN)
A firewall to protect your network from hackers
Possibly a bridge if you already have a section of network and you want your new network to connect to it
Server(s) to manage network functions such as network security, network file storage, shared resources (such as printers)
You would need to organise some other things:
Set up an account with an Internet Service Provider (ISP)
Get an Internet connection installed from the ISP to your location
Configure various bits of hardware and software so that everything worked with the network
Network security is the process of taking physical and software preventative measures to protect the underlying networking infrastructure from unauthorized access, misuse, malfunction, modification, destruction, or improper disclosure, thereby creating a secure platform for computers, users, and programs to perform their permitted critical functions within a secure environment.
As soon as your computer is connected to a network, you have to start thinking about security – security of your files, information, etc.
A network allows a person who does to have physical access to your computer (they are not sitting in front of it) to gain access all the same. If your computer is connected to a network, other people can connect to your computer.
A person who gains unauthorised access to a computer system is often called a hacker.
Hacking techniques used.
The easiest way for a hacker to gain access to your network/private data is to get your password or user details and simply login as though they were authorized. They can get your details by using tricks that make you give them your details. Examples of these are:
Phishing is a cyber attack that uses disguised email as a weapon.
How to stay safe from Phishing
Pharming is yet another way hackers attempt to manipulate users on the Internet.
Protect yourself from Pharming
Securing data online
A digital certificate, also known as a public key certificate, is used to cryptographically link ownership of a public key with the entity that owns it.