tech unit 2

Analog to Digital Converter

A device that converts analog signal to a digital quantity(infinite set of possible values to a countable set of possible values)

ASCII (American Standard Code for Information Interchange)

a world-wide code for the numbers used by computers to represent all the upper and lowercase Latin letters, numbers, and punctuations (there are 128 standards of this code which can be represented by a 7 digit binary number

Bandwidth

The amount of data that can be transmitted over a network in a given amount of time.

Botnet

a group of compromised computers or mobile devices connected to a network

they are used for DDOS, click fraud, spam distribution, storing illegal files, & malware distribution (they keep a very low profile, so people will not notice their device is part of this network)

Catfishing

Creating a fake identity or account on a social networking service to trick people into sharing their personal information or into believing they're talking to a real person behind a legitimate account, profile, or page

DHCP (Dynamic Host Configuration Protocol)

A network service that provides automatic

assignment of IP addresses and other TCP /IP configuration information.

DNS (Domain Name System)

this translates people-friendly names to IP addresses, it is an extremely reliable distributed database used billions of times every day

Domain Name

the part of a network address that identifies it as belonging to a particular domain, it consists of the hostname, second level domain, and top level domain

Hostname

the part of a domain name that is a specific computer in the domain

Second Level Domain

the part of a domain name that is managed by a registrar

Top Level Domain

the part of the domain that hints at who owns it

(ex: .com/.org/.net/.edu/.gov./.uk/.us)

Denial of Service Attack (DDoS)

a cyber attack in which an attacker sends a flood of data packets to the target computer, with the aim of overloading its resources

Drive-by Download

Program which automatically downloads when a user visits a web page (not even clicking on any attachments), it uses a browser's security holes to install malware (usually without user's knowledge or consent, the owner of the website may not even know their website has this)

Firewall

a part of a computer system or network that watches TCP & IP traffic, it allows acceptable packets and tosses packets that seem suspicious, if this is disabled then you have no protection from the outside world

Hop Count

The number of routers the data packet must pass through to reach the destination network

HTTP (Hypertext Transfer Protocol)

the protocol that uses the services of TCP, it uses Port 80 and was designed for communication between web browsers and web servers, it can also be used to transfer hypermedia documents

HTML (Hypertext Markup Language)

the written code that creates Web pages and links; a language all computers can read

IP (Internet Protocol)

This is the main communications protocol, works with TCP to address and deliver data packets across multiple nodes/networks, it is unreliable

(designed by Vint Cerf & Bob Khan ~ used by ARPANET)

IP Address (Internet Protocol Address)

A unique number that identifies a computer/device connected to the Internet, it is sometimes fixed (usually for servers) and sometimes changes every time the computer connects to the internet, it is a four byte number (x.x.x.x), each "x" represents a number between 0-225

ISP (Internet Service Provider)

A company that provides customers access to the Internet, (some main ones are Verizon, AT&T, Xfinity, T-Mobile)

Identity Theft

when someone uses another person's personal information to make a profit or do something illegal

LAN (Local Area Network)

2 or more computers that are physically close to each other that communicate without having to go out over the internet, each one of these networks has a MAC

(WiFi is an example of this)

MAC

the unique number that each LAN (Local Area Network) has that represents its physical address

Network Latency

the amount of time it takes for a packet of data to get across a network from one point to another

Packet

a block of data (1s & 0s) that are sent across a network with a specific format (contain a header & payload)

Packet Header

the part of a packet that contains the destination address, source address, the checksum (makes sure packet isn't corrupted), & the length (number of bytes of user data)

Packet Payload

the part of a packet which contains the actual user data

Packet Switching

a mode of data transmission in which a message is broken into a number of packets that are sent independently, over whatever route is optimal for each, and reassembled at the destination, there is no central point of control , and if a packet is lost only the lost packets are resent

developed by Paul Bran & Donald Davies in 1960

Palette

the set of colors chosen to be used in a picture

Image File Construction

1. include palette of colors used

2. give height & width of pixels

3. give pixel data (1 byte per pixel)

*or*

1. give height & width of pixels

2. give pixel data [R,B,G values] (3 byte per pixel)

Pixel

the fundamental unit of a digital image, it is a tiny square that has its own R, G, & B values (requires either 1 byte or 3 bytes depending on image file construction)

Phishing

An attack that sends an email or displays a Web announcement that falsely claims to be from a legitimate business in an attempt to trick the user into giving out their private information

Spear Phishing

a phishing attack that is personalized and targets a specific person (usually a highly-researched individual) to try and get them to disclose their username/password/install malware

Port

a number that is assigned to a specific TCP/UDP connection

Socket

this is needed to connect to a specific program on a specific computer, it contains an IP Adress & a Port

Protocol

a rule which guides how an activity should be performed

Data Communication Protocols

rules that allow computers/devices to exchange information with one another, any devices that follow these same rules can communicate with one another, these rules are layered (use the services of one another)

RFC (Request for Comments)

documents that define/standardized Internet protocols and those in various development stages.

Proxy Server (a.k.a. Proxy)

the "middleman" that handles requests leaving a network & can block you from accessing certain sites, this hides your network from the outside world, programs must talk to this-which then talks to the outside world

(without this you would not be able to access anything besides your local network)

Quantization

the process of mapping continuous infinite values to a smaller set of countable values, it approximates real-world values and transforms them into digital values

Quantization Error

the difference between the actual signal level and the integer value chosen to represent it

Ransomware

a type of malicious software designed to block access to a computer system until money is paid to the hacker

Router

device that forwards packets between computers (determines which way to send packets), it is built to handle a lot of data traffic, has connections to lots of networks, and can connect a LAN to the internet, it is essentially the "gateway"

more of these \= more reliable internet

Scareware

a type of malware designed to trick victims into giving up personal information to purchase or download useless and potentially dangerous software

Social Engineering

techniques that hackers use to trick a person into disclosing confidential information

ex: sense of urgency, create panic/fear for the victim

Sequence Number

A chronological number that TCP attaches to each packet so the destination host can, place packets into the correct order

Spam

digital junk mail that is sent in bulk to a variety of people, it is unrequested, disruptive, and can even contain malware that could infect your computer with a virus/spyware

Spyware

malware that someone can install on your computer/devices to track your every move, allowing them to see your personal information

TCP (Transmission Control Protocol)

a protocol that is reliable, converts messages into stream of packets, and reassembles packets into the message at the destination, it works very closely with IP (designed by Vint Cerf & Bob Khan ~ used by ARPANET)

Trojan Horse (a.k.a. Trojan)

malicious computer programs that trick users into willingly running it

(users don't know they are running the malicious program)

Unicode

A character code that enables most of the languages of the world to be symbolized with a special character identification (emojis are an example of the output of this code)

URL (Uniform Resource Locator)

A location or address identifying where documents can be found on the Internet, this is also known as a web address

Virus

malware that spread between computers & causes damage to data/software on that computer, it can be installed by downloading the malware (either intentionally or unintentionally), it NEEDS a host program

WAN (Wide Area Network)

a network that spans long geographical distances, it is a collection of LAN (local area networks) or other networks that communicate with eachother

Worm

a type of malware that spreads copies of inself from computer to computer, it does NOT need a host program/a human to download it, it is a type of Trojan

Zombie

a program that secretly takes over another computer for the purpose of launching attacks on other computers, it keeps a low profile on a computer so a user won't notice there computer is not in their control (this is the name of each computer that is in a botnet)

Internet

a global system of interconnect computer networks that use the internet protocol suit

(it is a network of networks)

Internet Protocol Suite

the internet uses this to link devices together, it consists of TCP & IP

World Wide Web (www)

an interconnected system of public webpages that is accessible through the internet

(it is an application built on top of the Internet, NOT the same as the Internet)

Format of an IPv4 Address

this is a 4 byte number (32 bits total) (x.x.x.x), each "x" represents a number from 0-225

the first "x" represents the country

the second "x" represnts the region

the third "x" represents the network

the fourth "x" represents the computer

IPv4

the dominant protocol for routing traffic on the Internet, specifying "to" and "from" addresses using a dotted decimal such as "122.45.255.0", it is the current version the internet is using

IPv6

the protocol that provides a large number of new addresses to route Internet traffic, using "from" and "to" addresses written as colon-hexadecimal notations, such as "fe80::42:acff:feaa:1bf0".

Zombies & Botnets

malware that is used for Denial of Service Attacks, click fraud, spam distribution, storing illegal files, bitcoin mining, & malware distribution

Client/Server Computing

a type of computing where clients (the computer) do NOT talk to each other directly, instead each client talks to the server which may send a message to another client based upon the first user's actions

Client Responsibilities

in Client/Server Computing it is the reponsibilities of this to handle the user interface, translate the user's request into desired protocol, send the request to the server, wait for the server's response, translate the response into "human readable" results, present the results to the user

Server Responsibilities

n Client/Server Computing it is the reponsibilities of this to listen for a client's request, process the request, return the results back to the client, maintain usefull/up-to-date info.

Cookies

small pieces of information that a web-site can send to your browser to identify you (the user), these are part of HTTP protocol, they frequently have a "user ID" number

Uses of Cookies

- remember user preferences (user data)

\[credit card info, login details]

- count distinct visitors (who each view on a page was from)

- store info in web shopping carts

On Personal Device's Browser

cookies are stored here so websites do NOT have to store user data

Visting a Website (the first time)

when this occurs the website sends cookies to your browser

Visting a Website (Again)

when this occurs your browser sends cookies back to the website that left your cookies on the browser

Google Search

this consists of three parts (the crawl, the index, & the query processor) which allows users to google to receive information

The Crawl

this part of the Google Search Engine consists of google constantly searching web pages and following links on web pages to other pages (this never stops and occurs ALL the time)

The Index

this part of the Google Search Engine is the building of the database of information that is found on web pages during the crawl