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 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 request Example: 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 ?

What exactly is a URL? / ? ftp:// : / / mailto: Example: Which protocol to use? www is the name of the web server (ares) cs.siena.edu is 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 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 server cs directs us to a sub network www 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 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 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 – 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 – 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 APNIC (Asia Pacific Network Information Centre) – ARIN (American Registry for Internet Numbers) - North America and Sub-Sahara Africa ARIN (American Registry for Internet Numbers) – LACNIC (Latin American and Caribbean IP address Regional Registry) - Latin America and some Caribbean Islands LACNIC (Latin American and Caribbean IP address Regional Registry) – RIPE NCC (Réseaux IP Européens) - Europe, the Middle East, Central Asia, and African countries located north of the equator RIPE NCC (Réseaux IP Européens)

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

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: ISP Domain Name Table …  … DNS Authority

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