paper 1 computing

problem with encryption

if they don’t encrypt and use safety measures personal data is leaked , if they encrypt - messages sent by dangerous individuals may be protected

types of online crime

obtaining personal info for identity theft or fraud, blackmail, cyber attacks, selling illegal stuff, sharing copyrighted material

data protection act 2018 principles

collect data lawfully and process fairly, only use for reasons specified , data must be relevant and not excessive, data has to be accurate and up to date, data mustn’t be stored for longer than necessary , data must be stored and processed securely

computer misuse act principles

no unauthorised access, no unauthorised modification, no unauthorised access for further illegal activities

copy right, design and patents act

prohibits copying , downloading and distributing copyrighted material

software licence

how a user can use a software

open source license

users can view and modify the source code

open source advantages

cheap, remove unwanted features, customisable

open source disadvantages

prone to errors , security risk - malicious code , need technical skills to maintain the code, difficult to recieve support as development is distributed

proprietary licence

code is restricted, users can’t modify or edit it

propriety advantages

well tested and secure, help and support, company can be held accountable if performance isn’t to standard

propriety disadvantages

users can’t modify code for their benefit, expensive, must rely on company for updates

o.s

software that helps to manage the resources of a computer system and provide the interface between the user and computer hardware

5 main tasks of OS

memory management, peripheral management, user management, file management, user interface

device driver

program that provides an interface for the OS to interact and communicate with an external force

user management

add , manage or delete accounts

file management

move, rename and delete files

GUI features

windows, icons, menu, pointer

CLI

text based, requires typing commands

Menu driven interface

displays data in a series of menus

utility software

dedicated softwares for the maintenance and organisation of a computer system

utility software types

anti-malware, data compression, encryption

fragmentation

when a file splits into different parts and is stored in different storage parts

defragmentation

collects together empty spaces so similar files can be moved together

GUI advantages

easy to use for beginners, allows multitasking

GUI disadvantages

uses more storage , RAM and processing power than other interfaces

CLI advantages

uses low processing power and little hardware resources

CLI disadvantages

have to learn commands, difficult to use

MDI advantages

low processing power, easy to use

MDI disadvantages

difficult and slow if poorly designed, too many menus can be annoying

malware

harmful program that seeks to damage or gain unauthorised access to your computer

virus

malware that replicates itself and spreads from system to system by attaching itself to infected files

worm

malware that replicates itself and spreads from system by finding software weaknesses

trojan

harmful program that pretends to be legitimate

spyware

secretly records info on someones computer to pass to the attacker

keylogger

secretly logs key presses

ransomware

locks files or holds private files for ransom

SQL injection

when a malicious SQL query is entered Into data input box on a website to gain unauthorised access

fire wall

manages incoming and outgoing network traffic to check if it should be given access to the network

user access levels

only allowing certain users to access and edit files

DDos

repeatedly sending requests to overload a server

brute force

computer software tests every combination from start to finish

social engineering

tricking others into revealing their personal data

data interception

data packets on a network are Intercepted by 3rd party

methods of prevention

anti-malware, penetration, firewall, secure passwords, encryption, physical security

encryption

scrambling data so attackers can’t understand it. converts plaintext into ciphertext using an encryption key.

physical security examples

biometrics, cctv, alarms, keycards, locks , security staff

network

more than one computer system connected together for communication and sharing of resources

LAN

computers are situated geographically close together, infrastructure is usually owned and managed by network owner

WAN

computers are situated geographically distant to each other, infrastructure usually owned by service provider

client server

network model where client sends request and server sends response

advantages of client server

easy to scale, easy to back up data and update software, hardware/software can be shared

disadvantages of client server

need to pay for IT technician, if server fails the whole network is down

p2p network

all computers are equal. a computer can send requests and responses

advantage of p2p

optimal for sharing files, not dependent on server

disadvantage of p2p

backups have to be performed individually on each computer, adding more devices slows the performance

what do data packets do

split large files into small pieces. send them to destination where they are reassembled

data packet order

header, payload, trailer

what does the header have

source and destination address, protocol , packet number

payload

the data

trailer

checksum - calculation to check for data errors or corruption in transmission

bandwidth

maximum amount of data that can be sent across a network at once

cloud storage

series of servers on the internet that you can upload files to via the internet

internet

global network of interconnected networks

advantages of star topology

easy to add new systems, security, speed

disadvantages of star topology

dependent on switch , extra hardware - expensive

full mesh advantages

multiple routes for data transfer, can withstand large traffic

full mesh disadvantages

redundant cabling, hard to set up, expensive

w.a.p

provides a link between wireless and wired networks

router

transfers data packets between networks

switch

connects devices on a LAN. sends data to exact computer using MAC address

NIC

hardware required to connect to a network. has a MAC address used to send data across a LAN

3 types of transmission media

ethernet cable , fibre optic, coaxial

DNS server process

type in domain name, query sent to local DNS server for corresponding IP address, finds the IP and sends it to the web browser, browser receives IP and displays website

what happens if the DNS server can’t find the IP

asks a larger DNS server

protocol

set of rules that allow devices to communicate

Transmission Control Protocol

allows data packets to be sent and received between computers. splits data into packets and reassembles them at destination

Internet Protocol

routes and addresses packets, gives devices an IP address

Hypertext transfer protocol

transfers web pages over the internet so users can view it on a web browser

HTTPs

encrypted and more secure versions of HTTP

File Transfer Protocol

transfers files across a network

Simple Mail transfer protocol

send email to a mail server and between mail servers

what do POP and IMAP do

recieve and store emails from a mail server

POP

deletes an email from sever once it has been downloaded to a device

IMAP

syncs the message with a mail server so it can be used on different devices

MAC address

unique hexadecimal number on a NIC. Can’t be changed. Used to identify devices in a LAN

IP address

address given to devices connected to a network. used to route packets in a WAN, can be changed

IPv4

32 bit address

IPv6

128 bit address in hex

4 layers

application, transport, network, data link

application

allows usage of the network - HTTP,HTTPS,SMTP,FTP

transport layer

TCP protocol

network layer

IP protocol

data link

ethernet/wifi sets out format of data packets and handles transmission errors

primary storage

fast memory which the cpu can access directly

what does primary storage consist of

RAM, ROM, cache

volatile storage

temporary storage, when computer turns off data is lost

non-volatile storage

long term storage, doesn’t get lost when computer turns off

RAM

randomly access memory - stores programs that are currently running

ROM

read only memory - non-volatile memory that stores the OS