How The Internet Works

Internet Basics
Well for starters if your reading this you have somewhat of an idea of how to get on the Internet, and how to get or find certain sites. This image gives a good overview of how it works in general...

Actually the Internet is made up of more then just the WWW ( World Wide Web ), as the diagram depicts just that. News, FTP ( File Transfer Protocol), and the WWW are just a few sections of the Internet. So how does it all work anyway?

The Internet is basically a vast network of personal computers, servers, and all types of machines communicating over a common protocol, the I.P., or Internet Protocol. Each computer or in general, each device connected to the Internet, or any network for that matter, needs an I.P. address unique to that device, but we will get into that more a bit later. Look at the Internet as a huge bookshelf, with millions of different books of all types. Each book is a different machine, containing different information. So how do you even get on the Internet in the first place? Lets take a look at the different ways to connect to the Internet.

How the Internet connection works
You need to connect to the Internet somehow to receive and transmit data. How you connect can depend on where you live ( you may have limited choices ) or your budget. A majority of home-based Internet users connect via a dial-up connection, using a modem that's inside ( or in some cases outside ) your computer. A modem is a device that converts analog signals from the PTN ( public telephone network ) into digital signals inside your machine. Hence what modem actually stands for ( MODulation and DEModulation ). Dial-up modem users usually pay an average of about 15-$20 dollars per month for usage via and Internet Service Provider ( ISP ) that provides them the means of connecting, viewing web-based media and sending and receiving e-mail. xDSL ( Digital Subscriber Line ) also uses the existing copper wire of your phone lines to connect you, but provides much greater bandwidth using special methods such as a distance limited digital line.

Viewing web pages
It would probably be silly for me to explain how to view web pages here, since you are obviously looking at this page reading this in one form or another. Viewing web pages is handled by an HTTP request, or HyperText Transfer Protocol. Basically your web browser, such as Internet Explorer or Netscape Navigator, sends a request for the document you select to the server that the document resides on, the server looks up the page, and sends the document to you, text, multimedia content and all. Your browser interprets the format and displays it on your screen. Depending on the document, you may view, save, or execute the file or document or the multimedia content.

How Electronic Mail works ( E-mail )
Checking for e-mail is similar to viewing web pages, although the process uses different software and protocols. Using your mail software ( Such as Outlook, Outlook Express, Netscape Messenger, Eudora, Pegasus, Pine, etc. ) your computer checks for mail using the Post Office Protocol ( POP ) and then sends mail using the SMTP ( Simple Mail Transfer Protocol ). You specify the servers under the software configuration, including the outgoing and incoming mail servers, and also your authentication information such as your username and password. E-mail that is addressed to you is processed by your Internet Service Provider ( ISP ) and is stored into a queue, and awaits for you to retrieve it. The mail server authenticates you, and then will allow you to receive mail that is awaiting in your Que. Sendmail servers do not usually require authentication, but most sendmail servers use and I.P. lookup table. That is, if your not a user of that particular system, and/or not logged onto that network related to that sendmail server, the server will not allow you to send messages. Outgoing mail servers ( mail servers that send e-mail OUT of your network, are called open relay's if they allow outbound e-mail traffic from users of other networks. Unfortunately there are thousands of open relay's on the Internet, and those that send junk e-mail ( SPAM ), use these servers to their advantage.

Internet Protocol and the Domain Name System
So how does the Internet know who 'www.icehousedesigns.com' for example? How does it know what machine out of millions that name is assigned to?

Enter the magic of I.P. addressing, or Internet Protocol. Each device is assigned an I.P. address on the Internet such as '207.219.345.212'. Certain machines are also assigned 'domain names' such as web servers. For example. Yahoo! can be reached by typing in http://www.yahoo.com in your browser window, or also by typing 64.58.76.227, which is the I.P. address of Yahoo's website. So who knows what I.P. is assigned to where? All domain names are handled by a company called Network Solutions, who are responsible for maintaining the whois database. No two names can be alike. The database is updated generally once or twice a day. There are also name servers from around the world and thousands of ISP's that update their name servers to match that of the whois database, generally once daily during off-peak hours. After all, it would be way to slow if we had only one database to use having millions of users polling it for information, and it is a lot easier to remember a simple name then a number right? Name servers are also called DNS servers, or Domain Name Servers. So when the average user types in a web server to visit, the DNS servers looks up the name for a match in the database which it updates from the whois database, once it finds a match it resolved the name to an I.P. Address, and it connects you to the appropriate machine.

Online shopping and security
One of the buzz words of the Internet have been 'e-commerce', or Electronic Commerce. E-commerce basically means purchasing goods or services over the Internet, but just how secure is giving out your personal information over the net anyway? Generally speaking, with a well-established company such as E-bay, whom have developed relationships with millions of users, security is very tight. All personal information, credit card numbers, etc., are all sent to a secure server, and encrypted usually with a 128-bit encryption strength, which is virtually impossible to crack or intercept. However, with anything, it is not 100%. Just be wary about giving your personal information out online, and make sure if you do it is through a secure connection.

All about Junk E-mail ( SPAM )
I've been doing some research on a hot topic that's been around since the early days of the web, It's called mail harvesting, and it's the number 1 way an e-mail address gets collected and used for unsolicited e-mail. This will help you all in probably answering a common question, "Why do I get so much spam?"

The answer all comes down to mail harvesting programs. Now I could rant on for hours about this, but I'm going to try to sum it all up as much as possible.

Today on the Internet lies many marketing companies that use mailing lists that send out letters to addresses. Some companies use opt-in lists ( meaning you have to add your address to the list, you SUBSCRIBE ) but many more use generated lists, this is where the unsolicited part comes in. There are literally hundreds of 'mail harvesting' programs out there that can do 1 or more of the following things:

A. Follow links for keyword searches through search engines to sites, harvesting e-mail addresses from pages. For example, if a marketing company wanted to build an e-mail database of web designers, all they would have to do is enter "web design services" for example, into the harvesting program, and it will follow the returned results from engines to the specific sites and harvest the addresses from there.

B. Visit a domain all in itself, pulling e-mail addresses from pages.

This includes USENET groups, discussion forums ( which are commonly hit ), and ISP's.

There are several ways you can protect your e-mail address from harvesting programs....

1. Don't post your e-mail address in any USENET groups. As far as message forums go, Don't put your e-mail address in your message body. If the forum has a profile for its users, you shouldn't enter your e-mail address in there either as it is still subject to harvesting. The most advanced harvesters are looking for preprogrammed patterns in the most popular message boards such as the UBB.

2. A good Harvester will only follow CGI links if they find a certain pattern. Most amateur spammers still use programs that specify how man directories deep they go into a site. From my results using http://domain.com/a/b/c/d/e/f/email.html ( for example ) will cut down on a lot of spam. If you have a cgi-bin use an e-mail form which stores the e-mail in the cgi code ( or PHP ). Also just to be safe change the name of the cgi mail to something different...other then using the word 'mail'.

3. If you are entering your e-mail address on a web page, use this sample javascript to help stop harvesting programs:

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