Menu

Internet

Most people that have been on the Internet for some years, have a general idea of the concept, and what makes the Internet ‘tick’. But there is a much bigger picture that goes unseen.

There are many factors that goes into making sure you get e-mail every day, are able to pull up a website, and check your stocks. When the Internet began well over a decade ago, it started small, and was used by the Department of Defense for communications in case of World War III.

Now, millions of people from all corners of the earth access the web daily, to play games, meet others, check the local weather, and for research. Friends are made, and business is conducted.

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 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.

As you see from this diagram, the user connects to the local phone switch, then over the PTN to the local carrier or another CLEC ( Competitive Local ExchangeCarrier ) then to the ISP’s equipment, hitting authentication, then logging in to the network. Of course if your using cable or wireless access to get on the Internet, your diagram would look different from that of the one above. If you were using wireless, your bandwidth would come from a local antenna or satellite dish, connecting you to your Internet Service Provider. If you were using cable, you would connect via your local cable company ( and then probably an ISP they outsource too ).

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:

<script
language=”JavaScript”>firsthalf=”username”secondhalf=
“@domain.com”document.w
rite(“<a href=\”mailto:” + firsthalf + secondhalf + “\”>Email
Me</a>”)</script>

Substitute the data for variable “firsthalf” with your username and the data for variable “secondhalf” with your actual domain for the e-mail address. Most web browsers are JavaScript enabled so that shouldn’t be much of a problem and basically safe to use as a simple solution. However one of the problems with this is that harvesting programs will attempt to put together any combination of phrases that even look like an e-mail address, but this would help.

Blocking user agents from domains with several well-known harvesting programs remains to be an option, but as I stated before there are far to many to block them all. Many other methods also embed tons of fake e-mail addresses into their web pages, in hopes the harvester will pick them up, resulting in a lot of bounced mail.

The pro spammers are now using reverse DNS lookup when compiling and sorting their lists. In the past its easy to generate false domains and e-mail addresses for spammers
to suck up. Now its easy for them to sort the lists if the domain isn’t a current one (i.e. false) its eliminated, therefore most of the anti-spam programs are ineffective. I’ve heard there is a way around this but its still being tested out.

I would recommend to those with web space to put up
some sort of script on your index page that will allow you to track the user-agent of visitors. Here is a brief list of the user-agents of more popular harvesting programs:

EmailSiphon
EmailWolf
ExtractorPro
Mozilla.*NEWT
Crescent
CherryPicker
WebBandit
NICErsPRO
EmailCollector

Just because a user-agent with a harvester program visited your page, doesn’t mean your address was successfully harvested.

Wireless Internet Fundamentals

Many people associate using wireless Internet with WAP. Wireless Application Protocol, uses WML (Wireless Markup Language). WAP is generally used with portable devices such as cell phones and other hand held devices. WAP was designed for speed, flexibility, size, and ease of navigation. What we are going to talk about in this article, is accessing the Internet via normal desktop computers, via a TCP/IP wireless network. WAP is good for those of you that need Internet access when you are on the run, however it’s not good for us that wish to have wireless access at home.

The wireless concept has been around since the mid 1800’s. The first example of wireless can be seen as far back as the very first experiments with radio. Since then we have seen cordless telephones, remote controlled toys, long distance calling via microwave, and now, wireless Internet.

The problem with wireless Internet is there have been many inexpensive means of broadband access prior to its implementation. The many faces of DSL and cable are just two examples. As of now, money and time are two very expensive factors when taking wireless Internet into consideration. As a new technology, upfront equipment costs and contracts can be very nerve racking to the average Internet provider. Then one has to take into consideration the various engineering issues associated with wireless Internet technology.

In today’s wireless Internet market, there are many key players developing fairly reliable, yet expensive hardware. As it is today, the market is growing rapidly, and technology in that area is growing right along side with it.

The Electromagnetic Spectrum

The Electromagnetic Spectrum, is the full range of frequencies, from radio waves to gamma-rays, that characterizes light.

As with other radio signals, wireless operates in the radio band on the Electromagnetic Spectrum, below the Infrared and visible bands of light. Starting from bottom to top on the Electromagnetic Spectrum we have:

The higher you get on the list, the closer together the crests on the waves get ( this is measured in wavelength ).

Electromagnetic radio radiation has the lowest frequency, the longest wavelength. Radio waves vary with wavelengths to about twenty meters apart.

The FCC ( Federal Communications Commission ) maintains and allocates every frequency in the radio band which is between 9 kilohertz and 300 gigahertz. For more about the radio spectrum and frequency allocation, visit the FCC Radio spectrum home page here.

As of now, a typical Line of site Internet connection operates at a frequency of 2.4GHZ, which is an unlicensed frequency. With current technology, this allows for decent bandwidth up to 10 miles in distance or more depending on engineering factors. With non-line of site, the frequency being used is 900MHZ. The same for cordless phones, and many other devices. However, currently distance is very limited at less than 3 miles.

The Fresnel Zone

The Fresnel Zone ( the s is silent, pronounced ‘fre-nel’ ) is the area between two line of site antennas where the radio waves spread out after they leave. The more obstructions in this area, the more the signal will weaken. As stated earlier, line of site is typically 2.4GHZ. Which is microwave. Microwaves can pass through walls fairly easy, but trees and other vegetation is much more of a problem. This is primarily due to the higher water content in vegetation.

Take a flashlight for example. The light radiates from its source, and the light dissipates and widens as it gets further from the flashlight itself. The highest concentration of light is in the center of the flashlight. Now take two flashlights, turn them on in the dark, and line them up so they are even, facing each other, about 10 feet apart. Now stand off to the side. Notice how the center is brighter than the rest of the area? Consider that the Fresnel zone.

Take this picture above. The two lines on the right and left represent two wireless radio towers, the pea green color represents the terrain, and the red represents the Fresnel zone. This red area is the most important area to keep clear of obstructions. The more obstacles in the way, the weaker the signal will become.

Summary

I hope this gives everyone a bit more insight on how wireless Internet works, and the technology and engineering that needs to be perfect to make it all work just right.

Bottom line is, despite several broadband Internet access types around currently, wireless will be a major player in the years to come. Especially for those that do not qualify for DSL, or wish to have something more reliable than frame relay or ISDN.