Recap of last class

History of the Internet– DARPA– ARPANet– Key Players

Other non-sense– File sharing (Napster)– Personal information security

(Experian)

Today’s Agenda

WWW Infastructure– URL details – Server details– How things work

Homework

Read pages 15-33 in IT. Finish lab

– All questions answered on paper

– Be prepared to show me your webpage and all the required components.

Questions

What does DARPA stand for? What does ARPA stand for? What is TCP/IP? Who invented it? Name 5 different types of content available on

the WWW

Questions

Approximately how many hosts currently make up the internet

– 2 million– 50 million– 300 million– 3 billion

What exactly is an internet host? Is a packet router part of the Internet or part of

the World Wide Web (choose one).

What is a web server?

Web server is an example of a host. Its just a computer with an

1. Internet connection with

2. Software that delivers

3. Content (files such as html, jpg, etc.) over

4. The World Wide Web using

5. HTTP

What exactly is HTTP?

Hypertext Transfer Protocol– an application-level protocol over TCP (Transfer

Control Protocol) – for distributed, collaborative hypermedia information

systems

How does the protocol work?

1. User’s computer establishes a TCP connection with a server

Server is specified in the URL Server listens for connection requests at a given port Port is just a “communication channel”

2. If no host is given in the URL, connect to the local host.

3. If no port is given in the URL, connect to port 80 (the default port).

How does the protocol work?

4. User’s computer sends an HTTP requestExample: GET index.html

5. User’s computer receives the requested document from the server

6. Close the TCP connection

What exactly is a URL?

Universal (Uniform) Resource Locator Its essentially a street address for content on

the WWW Its not a street address for a computer on the

Internet.– Computers have IP addresses

A URL is an address of a file, a service or even a person

URL’s

Each one of you has a URL Does anyone know theirs? Hint: Did you every receive email?

What exactly is a URL?

http://<host>/<path>?<query> ftp://<user>:<pass>@<host>:<port>/<cwd1>/<name> mailto:<account@site> Example: http://www.cs.siena.edu/home/index.html

Which protocol to use?

www is the name of the web server (ares)

cs.siena.eduis the network

location of www

home is a directory on the

web server

index.html is the name of a file in

the home directory

Translating URL’s

http://www.cs.siena.edu/home/index.html

First, you need to know what protocol to use to get the file

edu tells us the general domain/classification.siena directs us to a campus DNS servercs directs us to a sub networkwww is a computer on that sub-network

This is the actual directory path on the file server

Web Servers

Want to see the files on our web server?

There are about 600 files (mostly html and jpg)

I created them all 400-500 man hours Had I been hired as a

consultant I would have charged at least $75,000

Would have been a bargain for a company

Web Servers

Any computer can be a web server– CS Server: Compaq Intel Pentium III running an Apache web

server for RedHat Linux 7.1– CS Server: Adequate for about 50-60 http requests per

minute– CS Server: Actually get about 250 request per day

Why is the CS website so slow? It depends on where you are?

Web Servers

Rough map of the world as seen from our web server

Ken Swarner’s office

www (ares)

Roger Bacon

Siena College

Web Servers

Web servers do NOT have to be dedicated– There can be other software– Other processes running– Other purposes

Web servers are often– Application servers– Database servers– Domain name servers– Personal computers

Web Servers

Powerful servers– Multiple processors for handling simultaneous requests– Lots of memory (RAM) so file don’t have to be retrieved from

slow hard drives Called swapping RAM is perhaps the most important investment

– Thick bandwidth for dishing out lots of content Who has powerful servers

– Yahoo & Google– Major networks: CNN, ABC, NBC, CBS, etc. (ESPN)– Microsoft, IBM, & ??? (Dell???)

Web Servers

How can I set up my own web server.1. First, you need to get software

2. Second, you need a pretty good internet connection

3. Third, you need to register a domain name

4. Finally, you need to actually make some webpages

How much does this all cost? How hard is it?

Web server software

Apache (its free and its very good)– UNIX and Windows versions– Problems:– Not super easy to setup or configure– If you are not already a nerd, you’ll probably need a lot of

time.

Microsoft makes several different servers– Somewhat affordable– Somewhat easier to setup than Apache

Internet connections

Dial-up $10/month DSL $30/month Cable $40-50/month

Internet connections

T1 – $500 to $1000/month– 1-3 Mbps

T3– $5000 to $15,000/month– 3-45 Mbps

Internet connections

OC-3 – $30,000 to $50,000/month – 150+ Mbps

OC-12 – Over $1,000,000 year – 600+ Mbps

OC-48 – Good luck finding one– used internally by companies like MCI who sell the above

connections– 2400+ Mbps

Internet Connections

Siena– 3 or 4 dedicated T-1 lines (bundled?)– I’d estimate that we have 4-5 Mbps– I’ll get back to you on exact details

RPI (2 years ago)– Equivalent of 2 dedicated T-3’s – 50+ Mbps– 10-15 times Siena’s bandwidth.

Domain Names

Once managed by the InterNIC Internet Network Information Center

– Non-profit organization of professional– Public interest in mind– Still manages .org in North America

Who manages domains now?

Domain Names The Internet Assigned Numbers Authority (IANA) is the

overall authority for the IP Addresses, the Domain Names, and many other parameters, used in the Internet.

– APNIC (Asia Pacific Network Information Centre) - Asia/Pacific Region

– ARIN (American Registry for Internet Numbers) - North America and Sub-Sahara Africa

– LACNIC (Latin American and Caribbean IP address Regional Registry) - Latin America and some Caribbean Islands

– RIPE NCC (Réseaux IP Européens) - Europe, the Middle East, Central Asia, and African countries located north of the equator

Domain Names

Many companies act as a 3rd (and even 4th) party and will register your domain name with the proper authorities.

The InterNIC itself acts as a 3rd party in registering many domain names.

Registering a domain just reserves the name.

Spoofing

Ultimately, Domain name servers determine Which domain names are associated with Which hosts. Remind me to tell you a story.

Domain Names

Domain Names

To get the Internet to recognize your domain you have to get your ISP to add your domain to is Domain Name Server

This will have a cascading effect and eventually your domain can be reached.

My computer

IP Address:204.168.0.207

ISP

Domain Name Table…www.breimer.org 204.168.0.207…

DNSAuthority

Multi-tiered

Domain Names & Hosting

Companies that register your domain name are often ISP’s and

Will set you up with:– A domain name– A dedicated IP address– And, they make sure you get added to the right

tables– Associates your IP address with your domain.

On-site vs. Off-site

Most hosting companies have their own servers and will provide off-site hosting

– Off-site means they host your stuff on their servers– You don’t have your own servers on-site

Most ISP can set you up on-site if you have– Your own server– Your own support personal– Your own infrastructure

Other hosting options

Free services (under their domain name)– Angelfire– Geocities

Cheap services (under their domain name)– Roadrunner– AOL

Piggy-backing (under their domain name)– College– Company