INTERNET FUNDAMENTALS. The Internet A vast network of networks that electronically connects millions of people worldwide. Formed in 1968, when the U.

INTERNET INTERNET FUNDAMENTALSFUNDAMENTALS

The InternetThe Internet A vast network of networks that electronically connects millions of

people worldwide. Formed in 1968, when the U. S. Department of Defense’s Advanced

Research Projects Agency (ARPA) funded what would become the first global computer network—the Advanced Research Projects Agency Network (ARPANET).

The ARPANET allowed university and government engineers to research and work from any location on the network.

In the late 1980s, the Department of Defense decommissioned the ARPANET, and all sites switched over to the National Science Foundation network, called NSFnet.

The NSFnet, plus thousands of others, compose what has become the largest network of networks: the Internet.

The World Wide Web (www)The World Wide Web (www) The Web presents information through multimedia formats:

graphics, sound, animation, and video. The Web uses several tools to provide a visual layout:

Hypertext links Browser software Code structure

The Web resembles an electronic library – each location or site is like a book.

These books are created using Hypertext Markup Language (HTML).

These materials, along with interactive objects such as Java, JavaScript, and VBScript adds functionality to web pages.

How the Internet WorksHow the Internet Works Internet communication is made possible by the

Transmission Control Protocol/Internet Protocol (TCP/IP) software on your computer.

This software sends information to the computer with which you are connected, which then passes it on to other computers until it reaches its destination.

TCP/IP ensures that your information is transferred quickly and reliably. It divides your data into packets and sends each packet separately across the Internet.

The routing flexibility of TCP/IP software ensures the accurate and steady flow of information, regardless of any one user’s connection.

Internet ProtocolsInternet Protocols Hypertext Transfer Protocol (HTTP)

The set of rules required to exchange files, such as text, images, video, and multimedia content, across the Web. Files contain references to other files, so they are “linked” to one another.

File Transfer Protocol (FTP)Used to access programs and transfer files across the Internet.

Simple Mail Transfer Protocol (SMTP) – Electronic MailInvolves an outgoing and incoming mail server. You receive e-mail from an incoming mail server using the Post Office Protocol (POP) or the Internet Message Access Protocol (IMAP).

TelnetThe Internet standard protocol for remote terminal connection service. Some public Telnet servers are still widely used by administrators to remotely manage servers, firewalls, and routers.

Internet ProtocolsInternet Protocols Network News Transfer Protocol (NNTP) - Newsgroups

After registering with a newsgroup, you can read and post news

Gopher (An older menu-based program in UNIX-based systems used to find resources)One of the first tools developed to unite the Internet so that users could access the entire Internet rather than just one site. Gopher allows you to browse for information (usually text-based) without having to know exactly where the information is located. Most Gopher servers have been replaced with HTTP (Web) servers.

The Difference The Difference Between FTP and Between FTP and

HTTPHTTP

FTPFTP

File Transfer Protocol, or FTP, is a protocol used to upload files from a workstation to a FTP server or download files from a FTP server to a workstation.

It is the way that files get transferred from one device to another in order for the files to be available on the Internet.

When ftp appears in a URL it means that the user is connecting to a file server and not a Web server and that some form of file transfer is going to take place.

FTPFTP

Most FTP servers require the user to log on to the server in order to transfer files.

HTTPHTTP

In contrast, Hyper Text Transfer Protocol, or HTTP, is a protocol used to transfer files from a Web server onto a browser in order to view a Web page that is on the Internet.

Unlike FTP, where entire files are transferred from one device to another and copied into memory, HTTP only transfers the contents of a web page into a browser for viewing.

FTP is a two-way system as files are transferred back and forth between server and workstation.

HTTPHTTP HTTP is a one-way system as files are transported

only from the server onto the workstation's browser.

When http appears in a URL it means that the user is connecting to a Web server and not a file server.

The files are transferred but not downloaded, therefore not copied into the memory of the receiving device.

Connecting to the InternetConnecting to the Internet Elements required to connect to the Internet:

Computer, WebTV, mobile phone, or Personal Digital Assistant (PDA)

Dial-up modem, digital subscriber line (DSL) modem, or cable modem

Operating System: Windows 95/98/Me, Windows NT/2000/XP, Linux/UNIX, Macintosh

Telecommunications/Client Software: Web browser, e-mail or news client programs

Internet Connection (telephone line or cable connection): dial-up or direct connection to an Internet Service Provider (ISP) or Value-Added Network (VAN) such as America Online (AOL) or Microsoft Network (MSN)

Internet Addresses: Web addresses (e.g., www.msn.com), e-mail addresses (e.g., [email protected]), server addresses (e.g., ss1.ProSoftTraining)

Connection TypesConnection Types Dial-Up Connection

Use a modem to access the Internet on a per-use basis. The user accesses the ISP via phone line and when finished, disconnects from the ISP.

The speed of access is determined by the speed of your modem. To gain faster access, you can install an Integrated Services Digital

Network (ISDN) line, which is a digital phone line.

Direct Connection Provide continuous access to the Internet Convenient and fast and capable of handling high bandwidth

Domain Name System (DNS)Domain Name System (DNS) To access a website, you must enter the address of the web

server in your browser. The IP address (the dotted quad) is one way to identify the

server; however, most users prefer to use domain names because they are easier to remember.

The Domain Name System (DNS) translates IP addresses into easily recognizable names.

Examples: IP address: 72.64.56.86

Domain name: www.microsoft.com

Domain NamesDomain Names Each domain name is unique. It consists of

letters and numbers separated by dots and includes two or more words (labels).

The last label in a domain name is usually a two- or three-letter code called a top-level domain.

Example: www.microsoft.comServer (Host) Name Registered Company Domain Category

Domain Name (Top-Level Domain)

Domain Name SyntaxDomain Name Syntax A domain name, read left to right, specifies

general divisions, then specific companies, and individual computers (web servers or e-mail servers)

com = a commercial site

microsoft = the name registered by the company

www = the name of the web server at the company, also called the web site host

Domain NamesDomain Names A fully qualified domain name (FQDN) is the complete

domain name of an Internet computer. It provides enough information to covert the domain name to an IP address.

Top-Level Domains.com = commercial or company sites.edu = educational institutions .gov = U. S. civilian government.mil = U. S. military.org = organizations.net = network sites, including commercial ISPs.int = international organizations

Two-Letter Country Codes – categorize domains by country or region. For example: us = United States

au = Australia

Registering a Domain NameRegistering a Domain Name To register a domain name, your Internet Service Provider

(ISP), your employer, or you must make a formal request to a domain name registrar.

In the U. S., the Internet Corporation for Assigned Names and Numbers (ICANN) verifies which companies can serve as domain name registrars. The ICANN is responsible for accrediting its registrars.

Each country has a different process for registering domain names.

Domain name registrars activate domain names using a first-come, first-served basis.

If your domain name choice is available, you will receive notice via standard and electronic mail.

Network Solutions (www.networksolutions.com) was selected as one of the original five registrars.

Registrars provide the following services: Domain name registration Registration service forms for domain name transfers,

modifications, etc. Resource links for payment options and policies. Search capabilities for registered domain names, host IP addresses,

and last name/first name queries using WHOIS (an internet utility primarily used to query databases to determine registered hosts)

Registering a Domain NameRegistering a Domain Name

Uniform Resource Locators (URL)Uniform Resource Locators (URL)

A URL is a text string that supplies an internet or intranet address and the method by which the address can be accessed.

URLs start with the http:// prefix which identifies them as web pages using the Hypertext Transfer Protocol.

For example, if you enter the following web address:

http://www.microsoft.com

The URL will access a web page because it begins with http. It then contacts the web server and domain named www.icann.org. It will locate a file on the server.

INTERNET SECURITYINTERNET SECURITY

Internet SecurityInternet Security The Internet harbors many security hazards. Most hazards can be avoided using your browser and virus

protection. Other security features include:

Hypertext Transfer Protocol Secure (HTTPS) Authentication (verifying the identity of the user) Digital Certificates (equivalent to an ID card and digitally signed by

the creator of the certificate) Encryption (reduces the possibility of information theft by

scrambling information using mathematical algorithms; encrypted text cannot be understood by anyone with the correct encryption key)

Firewalls (restrict unauthorized users, retain control of private information, and prevent unauthorized export of proprietary information)

FirewallsFirewalls Personal firewalls are available for individuals’ computers.

They offer protection for an individual system rather than an entire network (used by businesses).

Tools for Windows Systems Zone Alarm – www.zonealarm.com Black Ice – www.networkice.com

Firewalls Inspect all incoming traffic for security threats When used in conjunction with anti-virus software, a personal

computer is very secure, provided that the user updates the anti-virus and personal firewall software frequently.

Example of FirewallExample of Firewall

Firewalls are systems that establish access control policies among networks. They can block information from entering a network or from getting out of that network, they can permit different users to perform different kinds of operations, according to the user's authorizations.

Do Cookies Compromise Do Cookies Compromise Security?Security?

CookiesCookies Cookies are small text files placed on a website visitor’s

computer so website managers can customize their site to a visitor’s preferences. They also gain information about visitors that could be used for marketing needs.

Unless you register with a site, cookies do not have access to any personal information about you.

The text is entered into the memory of the browser. The browser in turn stores the cookie information on the hard drive so when the browser is closed and reopened at a later date the cookie information is still available.

Web sites use cookies for several Web sites use cookies for several

different reasons:different reasons:

To collect demographic information about who is visiting the Web site. Sites often use this information to track how often visitors come to the site and how long they remain on the site.

To personalize the user's experience on the Web site. Cookies can help store personal information about you so that when you return to the site you have a more personalized experience.

Web sites use cookies for several Web sites use cookies for several different reasons:different reasons:

If you have ever returned to a site and have seen your name mysteriously appear on the screen, it is because on a previous visit you gave your name to the site and it was stored in a cookie so that when you returned you would be greeted with a personal message.

A good example of this is the way some online shopping sites will make recommendations to you based on previous purchases. The server keeps track of what you purchase and what items you search for and stores that information in cookies.

Web sites use cookies for several Web sites use cookies for several different reasons:different reasons:

To monitor advertisements. Web sites will often use cookies to keep track of what ads it lets you see and how often you see ads.

To collect demographic information about who is visiting the Web site. Sites often use this information to track how often visitors come to the site and how long they remain on the site.

To personalize the user's experience on the Web site. Cookies can help store personal information about you so that when you return to the site you have a more personalized experience.

Web sites use cookies for several Web sites use cookies for several different reasons:different reasons:

If you have ever returned to a site and have seen your name mysteriously appear on the screen, it is because on a previous visit you gave your name to the site and it was stored in a cookie so that when you returned you would be greeted with a personal message.

A good example of this is the way some online shopping sites will make recommendations to you based on previous purchases. The server keeps track of what you purchase and what items you search for and stores that information in cookies.

Web sites use cookies for several Web sites use cookies for several different reasons:different reasons:

To monitor advertisements. Web sites will often use cookies to keep track of what ads it lets you see and how often you see ads.

CookiesCookies Cookies do not act maliciously on computer systems. They

are merely text files that can be deleted at any time - they are not plug ins nor are they programs.

Cookies cannot be used to spread viruses and they cannot access your hard drive. This does not mean that cookies are not relevant to a user's privacy and anonymity on the Internet.

Cookies cannot read your hard drive to find out information about you; however, any personal information that you give to a Web site, including credit card information, will most likely be stored in a cookie unless you have turned off the cookie feature in your browser. In only this way are cookies a threat to privacy.

CookiesCookies The cookie will only contain information that you

freely provide to a Web site.

Cookies have six parameters Cookies have six parameters

that can be passed to them:that can be passed to them: The name of the cookie. The value of the cookie. The expiration date of the cookie - this

determines how long the cookie will remain active in your browser.

The path the cookie is valid for - this sets the URL path the cookie us valid in. Web pages outside of that path cannot use the cookie.

Cookies have six parameters Cookies have six parameters that can be passed to them:that can be passed to them:

The domain the cookie is valid for - this takes the path parameter one step further. This makes the cookie accessible to pages on any of the servers when a site uses multiple servers in a domain.

The need for a secure connection - this indicates that the cookie can only be used under a secure server condition, such as a site using SSL.

Cookies in Netscape and Cookies in Netscape and Internet ExplorerInternet Explorer

Both Netscape and Microsoft Internet Explorer (IE) can be set to reject cookies if the user prefers to use the Internet without enabling cookies to be stored.

In Netscape, follow the Edit/ Preferences/ Advanced menu and in IE, follow the Tools/Internet Options/Security menu to set cookie preferences.

For more information, see:The Electronic Privacy Information Center The Unofficial Cookie FAQ