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Communication and the internet (Network Security (Identifying…
Communication and the internet
Network
LAN/WAN
LAN
: a network of computers within same small geographical location. Managed independently
Examples:
schools, businesses, home
Advantages:
- you can share out put devices and documents etc. Fast, Cheap, Easy to set-up
Disadvantages
- limited to specific area
WAN
:connects separate LAN's over a large geographical area to form a network of networks. Managed by several different people
Examples:
The internet
Advantages:
- global, larger network available
Disadvantages
- costly, slow, not easy to set up
Topologies
Ring
Diagram
:
Advantages:
simple to transmit as travels in one direction, no collisions
Disadvantages:
Data must pass through each computer, if one machine is switched off there will be no data transmissions, if cable breaks there will be no data transmissions
Examples:
LAN's and WAN's
Definition:
Each node connects to exactly two others to form a continuous pathway
Star
Definition:
Each computer or client is connected individually to a central point or node which can be a file server, hub or switch
Diagram:
Advantages:
Data is only directed to the intended computer, traffic is kept to a minimum, if one fails the rest can still operate, easy to add new devices.
Disadvantages
If central point fails then so will entire network, requires lots of cable to connect all therefore expensive
Example:
commonly used in homes and offices
Bus
Definition:
Each device is connected by a t-piece to a main cable of link called the bus. At the end of the bus are terminators that stop signals reflecting back down the bus.
Advantages:
Easy to set up, cheap, easy to add to
Disadvantages:
Data collisions are common, if main cable fails then the whole network will too, if terminator is removed all network will fail
Examples:
computer motherboards.
Diagram:
Mesh
Definition:
Each computer or client is connected to ALL other computer in the network. Every computer sends its own signals but also relays data from others.
Advantages:
Data can be transmitted from different devices simultaneously, is one route fails there is alternate routes, can handle high volumes of traffic, adding more devices does not slow transmission
Disadvantages:
Overall cost is high, more cable is required, difficult to manage
Diagram:
Examples:
wireless networks
Protocols
Email
SMTP
-Simple Mail Transfer Protocol provides rules for sending email messages from client to server
POP3
- Post Office Protocol is used by a client to retrieve emails from a mail server. All emails are downloaded.
IMAP
- Internet Message Access Protocol. Unlike POP the messages the messages are read and stored on the server and don't have to be downloaded.
Network
TCP/IP
Transmission Control Protocol/Internet Protocol. It is a set or stack of protocols that allows a computer to communicate across a WAN
HTTP/HTTPS
- Hypertext Transfer Protocol provides rules to be followed by web browser and web server when requesting and supplying information. HTTPS is a secure version.
FTP
- File Transfer Protocol provides the rules for file transfer between computers. It is often used to transfer files that are too large for attachment to emails.
Wired vs Wireless
Wired
- devices are physically connected using either copper wire (transmits data as electric signals) or fibre optic cable (transmits data as pulses of light)
Advantages
: High bandwidth (10Gbps), high security as need to plug computer into socket, no interference
Disadvantages
: Difficult to install, expensive, poor mobility
Wireless
- Use radio waves to communicate.
Advantages:
easy to install, cheap, good mobility
Disadvantages
: low bandwidth (600Mbps), poor security as anyone within range can access, and it can be easy interfered with as signals can be affected by walls etc.
Network Data Speed
- speed that data can be transmitted through a communications medium.
Bits per second (Bps) = 1
Kilobits per second (Kbs) = 1000
Megabits per second (Mbps)= 1000000
Gigabits per second (Gbps)= 1000000000
Client Server/ Peer to Peer
Client- server
Two types of computer
:
File servers
- computer which control access and manage the network
Client workstations
- computers which allow users to run applications and to access the server and also network resources such as printers
Diagram:
Using the network:
Clients connect to the servers using their network addresses to access their services, programs and data stored on them. The servers then obtain the address of the client and send the requested data and services. Servers are responsible for network security by allocating login names and passwords to users.
Peer to Peer:
One type of computer:
All computers are connected to each other. They are all equal and can communicate with each other directly rather than going through a server
Using the network:
each client acts as the server as other clients an share programmes, data and printers etc. security is distributed as each user can grant the rights to others. Data is stored on each client rather than centrally and each user is responsible for backing up each client
Diagram:
Network Security
Cyber attacks
Social
Shoulder surfing
- finding out peoples personal login details by watching them enter them.
Phishing
- involves emails claiming or appearing legit trying to get personal details
What is it?
- an attempt by hackers to damage or destroy a computer network or system. They exploit humans using a network or technical weaknesses to: obtain data stored on the network, delete or modify data or make the system unusable
Technical
Unpatched Software
- the use of software with security flaws being exploited by hackers
USB devices
-employees could attach portable devices in order to download sensitive information or install dangerous software
Smart Devices
- the use of unprotected devices such a kettles and fridges being hacked
Eavesdropping
- the interception of digital communications
Importance
- business can protect customers data. Data stored may be private eg medical records. Protects peoples finances
Access controls
- used to set a network user's rights to the files and data stored. This ensures that confidential data is seen only by the requested users and files are not modified or deleted
Firewalls
- protects a network connected to a WAN. Provided by hardware or software and configured to prevent communications from entering the network or prevent programs and users from accessing the internet
Identifying vulnerabilities
Penetration Testing
- used to test a system for vulnerabilities. Testing assesses unauthorized access, security awareness and demonstrates effectiveness of security policies
Ethical Hacking
- a computer expert working systematically attempting find vulnerabilities with permission of the owner
Commercial analysis tool
- assess computers, systems, networks and applications for security weaknesses. Can only highlight weaknesses that have already been identified. They can be bought be hackers and used badly.
Review of policies
- Network policies are those that set out what users can and cant do, when backups will be made, where they will be kept, when software patches are applied and who applies them and what should be done if there is a problem.
Authentication and validation
- Authentication is the process of determining whether someone trying to log into the network is who they claim to be. All entries are then validated
Physical security
- access doors kept locked, biometric security recognition, swipe cards, burglar alarms, chains, locks, CCTV
Reasons for:
ensures only authorised users can access the network and its resources and only what is relevant to them. Prevents misuse. Prevents damage to hardware.
Internet and WWW
The Internet
- a global system of interconnected computer networks that serves billions of users worldwide
ISP
- internet service provide; needed by individual users to organise access.
Every computer has an
IP address
to communicate across the internet
World Wide Web
- a service that runs of the internet. Provides access to web pages which are connected together using hyper text links. Together they form websites which are hosted on computers throughout the internet
HTML
- Hypertext mark-up language which is a scripting language as it describes the format and layout of an object.