CodeHS: The Internet

Entertainment

-YouTube -online gaming -memes

Complications

-access to copyrighted material -anonymity -censorship

anonymity

-big question of how identifiable Internet users should be -equality on the internet -cyber bullying

The Internet...

-connects devices and networks all over the world -helps people collaborate to solve problems -helps people communicate

Digital Millennium Copyright Act (DCMA)

-copyright law -made piracy illegal on the Internet

The hierarchy helps the system scale

-easy to add a new layer -easy to ass a dingle element to a layer - each layer is only in charge of a small amount of information -searching one layer is much faster than searching every possible domain

Methods to send information

-electricity -light -radio

Internet address

-every device has its own unique address -data has a to and from address -the addressed follow a standard, agreed upon format

router

-forwards a request from one computer in a network to another -connects computers in a network by acting as the middle man

cyberwarfare:

-hacking into gov. computer systems

cybercrime:

-identity theft -stealing money - stealing private info -controlling private computers

The Internet

-is a massive network of routers -a network connecting individual networks

Online learning

-leaning is becoming more and more blended -online courses offer a wide array of subjects -benefits to educators and students

How to combat the divide?

-lite sites -mobile and wireless computing -networks and infrastructure provided by both gov. and companies

Open Source movement

-movement to make all info and products free for all -collaborative creation of products

access to copyrighted material

-peer to peer networks allow people to share content that isn't theirs

DNS Spoofing

-pretending to be a DNS server -feed computer the wrong IP address -your browser goes to a false website

cybersecurity

-protocols for encrypting/ decryption info - security software - following best practices

censorship

-should google display search results that have explicit or illegal content? -should a government be able to filter what content its citizens see on the Internet

DDoS (Distributed Denial of Service attack)

-spam a website so much so fast that is crashes and sometimes spits out valuable info as it crashes

IPv6

128 bit version of the protocol -each address is made up of 128 bits -made up of 8, 4 digit hexadecimal values 2^128

How to find possible addresses

2^x x= the number of bits the address is

IPv4

32 bit version of the protocol -been around since the 80s 2^32

IP Example: 93.184.216.34

93 = network 184= sub network 216=sub sub network 34= device

What is the Internet?

A philosophy of making information and knowledge open and accessible to ALL A network of networks Built on open, agreed upon protocols A way for all humans and all machines to communicate with each other

Impact of the Internet

Collaboration Communication (dissemination of information) Crowdsourcing Anonymity Censorship

What does the Internet enable?

Community supported causes (match4lara) Collaborative problem solving at a massive scale (foldit) Distributed computing (folding@home) E-commerce

Communication

Email Video calls Social media

HTTP: request

GET: /homepage.html HTTP/1.1 Host: www.example.com Content-Type: text/html Content-Language: en

HTTP: request and response

HTTP/1.1 200 OK Server: LiteSpeed Content-Type: text/html Content-Language: en

Who decides these protocols?

Internet Engineering Task Force -an open community of engineers, designers, vendors, and researchers, concerned with the evolution and smooth functioning of the Internet

Fiber Optic Cable (light)

Pro: long distance Cons: Very expensive -covers most of the distance on the Internet? -used by Internet providers Bright light: 1 Dim Light 0:

Ethernet cables (electricity)

Pros: cheap Cons: only covers medium distances High voltage: 1 Low "": 0

DNS hierarchy

ROOT (where is me) TLD (where is codehs.me) Second level domain (where is karel.codehs.me) Subdomain (the page)

Requesting a web source

Step 1: Check memory/cache (sees if you have already visited the website) Step 2: Ask a root server Step 3: Ask a TLD server Step 4: Ask a hosting server Step 5: Save in cache Step 6: Send the request

Viewing a Web Page

Step 1: The URL Step 2: Create an HTTP request Step 3: Use DNS to get the IP address Step 4: TCP/IP breaks the request into packets Step 5: packets are routed to the proper IP address Step 6: The original request is pieced together from the packets Step 7: Server creates an HTTP response Step 8: TCP breaks us the response into packets Step 9: the response packets are routed back to the computer Step 10: the original response is pieced together from the packets Step 11: The page is rendered

How do they work

TCP/IP, DNS, Routing, all work together to send packets over the Internet and HTTP makes sure the information inside the packets can be understood

TLD

Top level domain server -com, gov, edu, org, me, de

network

a group of 2+ computer systems liked together

protocol

a widely agreed upon set of rules that standardize communication between machines

how do computers find each other?

addressing

Cyber security problems

all info on the Internet is sent over shared wires - credit cards, passwords, emails, bank accounts can all be read by a cyber criminal

How is the bandwidth of a network measured?

bitrate. higher bitrate means higher bandwidth

bandwidth

capacity of data transfer in as system measured by bitrate low: 1 bps high: 5 mbps

How to combat

cryptography (open standards for encryption) SSL/TLS (secure sockets layer/transport layer security) https:// (secure bc the info is scrambled and can't be easily read) antivirus software (detect and delete malicious software) -use strong passwords -don't repeat websites between websites - install security upadates -think twice before clicking a link or installing program -don't click links in emails from people you don't know - don't visit websites when your browser tells you not to - don't download files when your browser warns you not to

Distributed computing

donate computing power rather than personal puzzle solving time

cost

how close is the IP address? is this router trustworthy? is the connection fast?

redundancy

multiple paths exist between two points - makes the system fault tolerant if one router breaks added routers = better performance

Digital divide

online access varies in different countries and socioeconomic groups -hoe does this affect those groups? - access to info - ability to communicate -power

E-commerce

online shopping - buy directly from retailers - easily purchase from other people who don't have a physical store - able to find the best product at the lowest price Crowdfunding - allows people to raise money to fund projects

Access to Information

open databases of scientific publications wikileaks -free and subscription based - scientific papers are no longer for students only - transparency of information -potential danger in classified secrets being public

Transmission control protocol

protocol that allows for sending multiple packets between two computers. TCP checks that all packets arrived and that they can be put back together in the proper order -adds a number to each packet so what order they were sent is recorded (can be put back together if they're sent out of order, missing packets cna be requested) -metadata for TCP includes(to address, from address, message size, order number)

Internet Protocol (IP)

protocol that defines the layout of an Internet address -it's hierarchical (in order of importance) -scalable (easy to add more networks and devices) -expressible as a 32 bit number

HTTP (hypertext transfer protocol)

protocol that standardizes the language for talking to web servers and receiving web resources -defines how computers request and receive hypertext information

public key encryption

public key encrypts and private key decrypts

Citizen science

science that harnesses the solving capacity of thousands of people on the Internet to solve complex problems

what is the birtrate of a system?

the amount of data (in bits) that can be sent in a fixed amount of time

routing

the process of sending data between two computers on the internet. The data is sent through routers that determine the route

what is the latency of a system?

the time it takes fora single bit to get from sender to receiver

latency

the time it takes fora single bit to get from sender to receiver low latency = fast connection fiber optic cable has a low latenct

Domain Name System (DNS)

translates names to IP addresses -registers domains and turns domains into an IP address

packets

units of data sent over a network -all data is broken down into packets -packets labeled with metadata (from address and to address) -when they arrive they're pieced together -layout of a packet is defined by a protocol All packets must have: -To IP address -From address -actual data being sent

Sending bits

uses time so when the bit doesn't change, it still records it 10001 with no time is 101 10001 with time is 10001

CAs

verify the public keys of the websites you use -twitter gives you a public key in order to communicate securely -A CA will verify that the public key does in fact belong to twitter

Radio waves

wifi routers and cell towers Pros: wireless Cons: short distance High frequency: 1 Low "": 0