NETWORKING AND THE INTERNETHow computers talk to each other

and

How that allows you to post selfies and bully each other

WELCOME TO THE INTERNET

WE’LL BE YOUR GUIDE TODAY.

THE INTERNET

The internet is a massive global collection of networks that all talk to each other, forming a worldwide “web” of networks that share information with each other.

A network is the term used for a local collection of computers that share information with each other.

A network does not necessarily have to connect to the internet. For instance, you can connect a bunch of older computers in your house to share data with each other, without an internet connection.

NETWORKING

Before you can understand the internet you need to understand local area networks and TCP/IP protocol.

Local area networks, also know as LANs, are a computer network that interconnects computers within a limited area such as a home, school, computer laboratory, or office building, using network media. Network media means wired or wireless adapter

technology In order to tell one computer apart from another,

they each need their own address, given to them by the TCP/IP Protocol in the form of an IP address.

THE BREAKDOWN

So what is a local area network (LAN)? Any number of computers in a given area, all

linked together to share data, is a Local Area Network, also known as a LAN.

Your network at home probably has at least 1-2 computers and phone or a tablet on WiFi. They’re all connected to the router given to you by AT&T or Comcast, and that is a Local Area Network.

Those are a few computers and devices that share one entry point to the internet, through the router.

Next door, your neighbor has their own set of devices and their own router connecting them to the internet, meaning there is another, unique LAN next door.

EXAMPLES OF LANS AROUND YOU

This school is a prime example of a LAN. Every one of these computers all connect via a wired or wireless connection through a main router in a secret and very noisy closet, which connects us all to the internet.

EXAMPLES OF LANS AROUND YOU

The local library is its own LAN as well. It has multiple computers for use and its own connection to the internet.

Any store that offers free WiFi, such as Panera, Starbucks, etc. is offering a Wireless LAN connection for your wireless devices.

TCP/IP PROTOCOL AND IP ADDRESSES

TCP/IP (Transmission Control Protocol / Internet Protocol) is the basic communication language of the Internet.

TCP and IP are two different but very important parts of data transmission.

TCP (Transmission Control Protocol) TCP is the system that breaks the data into

chunks, called packets. Depending on the size of the file it may take many packets to send data from one computer to another.

But how does the data know where to go?

TCP/IP PROTOCOL AND IP ADDRESSES

Internet Protocol (IP) IP is the system of identifying and addressing

computers with unique numbers, called IP addresses.

Each computer gets an address called an IP address to distinguish itself from any other computer, so that the data always gets to the right place.

DATA TRANSMISSION DEMONSTRATION I need seven volunteer students to stand up right

now. One person will be the data packet, one person

plays the role of the router, the other five of you are now computers.

Grab a piece of paper if you are a playing as a computer. Write down one of these IP ADDRESSES: 192.168.1.100 192.168.1.101 192.168.1.102 192.168.1.103 192.168.1.104

Two computers CANNOT HAVE THE SAME IP ADDRESS!

DATA TRANSMISSION DEMONSTRATION

If you are the router, please write down the names of the students who are computers and who has which IP address.

In a modern LAN, all data passes through the router to get from one computer to another. The router knows who is who, so when data is trying to get through the network, it needs to ask the router where the destination is.

DATA TRANSMISSION

As the data packet, your job is to get from one IP address to the other. To do so, you must grab the information from my desk, ask the router where to go, and then deliver it. I will choose the first destination.

That computer may choose to send a different packet of information anywhere it chooses. Every time you’re looking to go somewhere, you must ask the router where to go again.

Recap: In a simple Local Area Network, all data transmits between computers through a router.

A router holds all the information about which computer has which IP Address so that data packets find its way to the right place.

Sounds easy, right?

OH GOD WHY IS IT NEVER EASY

You should know by now that is NEVER EASY. IP addresses are finite. That means there

can only be so many of them, and they can run out.

IP Addresses are made of four 8-bit numbers. 8 bits… I remember learning about bits… Each portion of an IP address has a

maximum value of 255 Remember, in binary, 8 bits of data is

128+64+32+16+8+4+2+1, which equals 255.

An IP address looks like this: 10.152.252.87

And since there are only four spaces going from 0-255, that means that 255x255x255x255 was the total number of available IP address. That equals 4.2 billion addresses.

OH NO, NOT THE MATHS. Some quick math:

4.2 billion IP(v4) addresses 7 billion humans Not everyone has internet access, maybe 4 billion

people have access reliably But not every human has only one computer… let’s think

smaller. There are 318 million Americans… Not all of them have internet either, but lets assume 200

million have internet access… Some of those Americans have a lot of internet

connected devices – PCs, laptops, phones, tablets… let’s say 5 per house…

200 million times 5 is 1 billion. Roughly. Give or take. Want to do the math again with China? They have 1.2

billion people. After we’re done with China we’ll still be only TWO COUNTRIES down and most of the IP addresses are pretty much gone. And India is large too.

SO, WHAT WAS THE POINT?

Clearly, not every device has a true IP address.

In a Local Area Network, the router has the only real IP Address connecting it to the internet, and it loans out local (fake) IP addresses to distinguish computers from each other within its own Local Area Network.

What does LAN stand for? How do you tell one computer apart from

another on a network? What does TCP stand for? What does IP stand for? What device in your home has all the

addresses of your computers so data knows where to go?

What do you call a chunk of data broken up using TCP?

What is the maximum value of an 8-bit number?

THE ANALOGY

You could try to make sense of this like how the mail is delivered. Your house only has one address. It’s 123 Fake

Street, Davie FL. Within this house, however, there are five

people living inside. All the mail goes to 123 Fake Street, but depending on whose name is on the envelope, depends on who opens the mail.

Your house address is the router’s IP. Your mail is a data packet. Your house is the LAN. Your name on the envelope (packet) is a local

(fake) IP address. The mailman is like the internet. Only slow and

sweaty.

THE ANALOGY FLIPPED You could try to make sense of this like how the mail

delivered. Your router only has one address. It’s 128.2.2.205 Within this router, however, there are five devices

connected. All the packets goes to 128.2.2.205, but depending on whose name is on the packet, depends on who gets the data.

Your router’s IP is your home address. The data packet is like mail coming to your house. Your house is the LAN. Your computer’s name is in the packet like your

name might be on an envelope. The internet is like a high-speed digital mailman,

only with faster legs and is full of cats.

IP ADDRESSES RESERVED

When establishing a way to solve this problem of running out of IP Addresses, several numbers were blocked out from being used so that routers could use them to assign their fake IP addresses.

192.168.1.1 192.168.0.1 192.168.1.100 These are just a few of the IPs reserved for a

router. So while the router takes an IP address like 128.2.2.205, the computers managed by it take addresses like 192.168.1.20, 192.168.1.21, etc…

DATA TRANSMISSION DEMONSTRATION

I need thirteen volunteer students to stand up again right now. 2 groups of 6, and 1 by themselves.

Each group of six consists of a router and five PCs.

Group A is a network of five computers in San Jose, and your IP address for your router is 2.58.64.205. Write that down!

Group B is a network of five computers in Weston, and your IP address for your router is 10.254.208.102. Write that down!

Group A IP addresses: 192.168.1.141 192.168.1.143 192.168.1.157 192.168.1.202 192.168.1.19

Group B IP addresses: 192.168.0.12 192.168.0.254 192.168.0.208 192.168.0.96 192.168.0.14

OH BOY HERE COMES THE FUN In order to get the data packet out of Group A and to

the correct computer in Group B, we’re going to need to modify the previous demonstration.

A computer in Group A needs to call a computer in Group B via Skype.

Group A: Computer 192.168.1.143 Your Skype Username is LovelyTwerk68.

Group B: Computer 192.168.0.208 Your Skype Username is DapperDerierre419.

The packet must take the request from LovelyTwerk68 and talk to DapperDerierre419 to establish a connection between the two.

TO DO THIS

The packet must carry data not only of where it came from, In this case, 2.58.64.205/143 initiated the

request But it must also holler to the Skype servers

for where DapperDerriere419 is and get that LAN’s IP address.

Then it must ask the router which local IP is DapperDerriere.

It must deliver the request and with the original information in hand of where it came from, and find its way back to establish the connection.

Remember: You are data. You are only as smart as you are allowed to be. You can’t take shortcuts unless you’re told to. So you have to talk to someone in each step to move back and forth.

Once you understand this concept, you can understand the internet as a whole and we can start going deeper into how the internet works.

THE HISTORY OF THE INTERNET

The internet started as a research project funded by the US Government in 1969. This was called ARPANET.

ARPANET grew slowly in the beginning, as the first routers, called Interface Message Processors, cost $500,000 in today’s dollars.

By 1973, ARPANET had expanded internationally to include not just key locations in the US, but also locations in England and Norway.

This was not an internet you were familiar with. This was an internet that consisted of remote access to databases. Mostly just text interfaces.

THE INTERNET GROWS. THE CATS ARE COMING.

By 1971, email had been invented, as well as FTP, File Transfer Protocol.

It wasn’t until 1982 that the military could see ARPANET’s growth was going to become too much for their resources to manage. Instead of being one network with hundreds of nodes, they decided that regions should be smaller “Networks of Networks” that can communicate with each other.

To make this happen, TCP/IP was standardized and implemented January 1, 1983. This is the birth of the modern internet.

Today, the internet is made of 40,000 smaller networks using TCP/IP in one big “web”.

In 1994, President Clinton’s administration made the internet available to the general public in a move called privatization.

Commercial companies, such as Sprint and AT&T, took over managing the major pipelines of the internet, called backbones.

Backbones are physical lines of internet cabling running across the country, made of fiber optic cable, connecting all the major networks across the country for efficient data transmission.

THIS IS JUST THE MAJOR NETWORKS IN THE USA

What is the maximum value of an 8-bit number? What device in your home has all the addresses of your

computers so data knows where to go? What does IP stand for? What day was TCP/IP standardized, giving birth to the

modern internet? What do you call a chunk of data broken up using TCP? What was the name of the internet before it was the

called the internet? How do you tell one computer apart from another on a

network? What does TCP stand for? What does LAN stand for? What do you call a physical line of fiber optic cable

connecting major networks?

INTERESTING SIDE NOTE

Data packets are still just binary data, and binary data is electricity.

Electricity always take the shortest path from where-ever it is, to the ground.

In data transmission, data packets are similarly routed to always take the shortest path.

Routers measure the distance between paths with a term called ping.

Ping is the time in milliseconds for a packet to get to a destination and back. The lower the time, the faster the route. Routers remember that and collectively build the fastest route to get data anywhere.

SO, HOW DO WE GET ON THE INTERNET?

The internet is all around you now. It’s wired through the walls and broadcasting through your head right now as high-frequency radio waves.

But in order to get on to the internet, you need an ISP, or Internet Service Provider.

An Internet Service Provider is a company that offers you the service of connecting to the internet. Where we’re from, you’re familiar with:

AT&T uVerse/Wireless Comcast xFinity/WiFi Verizon Wireless, Tmobile, MetroPCS, Alcatel, Sprint for

phones AOL Dialup (God help you)

There are all examples of ISPs.

HOW DO WE GET TO AN ACTUAL WEBSITE?

All websites are made of code called HTML. HTML stands for HyperText Markup

Language. HTML is the standard language to make a

website that any web browser can read. A browser is a program that allows you to

decode HTML into a web page. Examples of browsers are:

Microsoft Internet Explorer Mozilla Firefox Google Chrome Apple Safari Opera

DID YOU KNOW…?

When you choose to go to a website, you are not actually going to, say, www.google.com

All websites on the internet are defined by their IP Addresses.

Nobody expects you to remember that Google is 64.233.160.0

To cater to the human ability to work with words better than numbers on average, they invented the Domain Name System (DNS)

DNS SERVERS

A DNS Server Address is programmed into your internet settings by your Internet Service Provider.

Instead of going to 64.233.160.0 for Google, the browser allows you to type www.google.com. It then asks the DNS server what the IP address is for it, and connects you to it.

This all happens in less than a second!

ANATOMY OF A WEB ADDRESS

A website address is known as a URL, or Universal Resource Locator.

Any address, such as http://www.msn.com ftp://danbuck.freeonlinestorage.com www.google.com

The above are all URLs, which is the term used for what you basically call a link.

http://www.video.google.com

1. google.com is called the domain name2. .com by itself is called the top-level domain.3. “video” is called a subdomain.4. http:// is the protocol used to connect.

1. HTTP stands for HyperText Transfer Protocol2. HTTP is the standard protocol to transfer a website.

5. video.google.com is called the hostname.

LAST BUT NOT LEAST

Clients and Servers In any data transmission scenario, one is usually

the client and the other is the server. A client us usually a computer that initiates a request

by sending out a packet for a connection. A server is a computer that is sitting by, minding its

own business and waiting for a client to ask for their services.

EXAMPLES

In the instance where you are connecting to a website, you are the client. You are initiating a connection to a website, and generating a packet to seek out the website for a connection.

The website is the server, waiting by the phone desperately waiting for you to call them, forever alone. Once it sees you want in, it answers the phone and establishes a connection to its website, allowing you to use it.

ANOTHER EXAMPLE

In the demo where you had Skype connections, the Skype program is the client, logging in to the Skype server to tell the service you are online. The client periodically checks in to remind the service it’s still online.

Once someone else wants to call you, they become the client by seeking you out, and technically you become the server by responding to the call. The Skype service only functions to allow users to find each other, and once they do, the connection is from client to client, with one computer acting as the server. This, however, does not prevent the government from asking Skype to listen in on your calls.