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More Internet for Dummies...

At the time the Internet was still under some semblance of control by the National Science Foundation and was connected to only a few thousand computers. The Net was shut down and all viruses purged from its host computers, and then the Net was put back into operation. Morris, meanwhile, was put in jail.

There is some concern that, despite improved security measures (for example, "firewalls"), someone may find a new way to launch a virus that could again shut down the Internet. Given the loss of centralized control, restarting it could be much more time-consuming if this were to happen again.

But reestablishing a centralized control today like what existed at the time of the “Morris Worm” is likely to be impossible. Even if it were possible, the original ARPANET architects were probably correct in their assessment that the Net would become more susceptible for massive failure rather than less if some centralized control were in place.

Perhaps the single most significant feature of today's Internet is this lack of centralized control. No person or organization is now able to control the Internet. In fact, the difficulty of control became an issue as early as its first year of operation as ARPANET. In that year email was spontaneously invented by its users. To the surprise of ARPANET's managers, by the second year email accounted for the bulk of the communication over the system.

Because the Internet had grown to have a fully autonomous, decentralized life of its own, in April 1995, the NSF quit funding NSFNET, the fiber optics communications backbone which at one time had given NSF the technology to control the system. The proliferation of parallel communications links and hosts had by then completely bypassed any possibility of centralized control.

There are several major features of the Internet:

* World Wide Web -- a hypertext publishing network and now the fastest growing part of the Internet.
* email -- a way to send electronic messages
* Usenet -- forums in which people can post and view public messages
* telnet -- a way to login to remote Internet computers
* file transfer protocol -- a way to download files from remote Internet computers
* Internet relay chat -- real-time text conversations -- used primarily by hackers and other Internet old-timers
* gopher -- a way of cataloging and searching for information. This is rapidly growing obsolete.

As you port surfers know, there are dozens of other interesting but less well known services such as whois, finger, ping etc.

The World Wide Web

The World Wide Web is the newest major feature of the Internet, dating from the spring of 1992. It consists of "Web pages," which are like pages in a book, and links from specially marked words, phrases or symbols on each page to other Web pages. These pages and links together create what is known as "hypertext." This technique makes it possible to tie together many different documents which may be written by many people and stored on many different computers around the world into one hypertext document.

This technique is based upon the Universal Resource Locator (URL) standard, which specifies how to hook up with the computer and access the files within it where the data of a Web page may be stored.

A URL is always of the form http://<rest of address>, where <rest of address> includes a domain name which must be registered with an organization called InterNIC in order to make sure that two different Web pages (or email addresses, or computer addresses) don't end up being identical. This registration is one of the few centralized control features of the Internet.

Here's how the hypertext of the World Wide Web works. The reader would come to a statement such as "our company offers LTL truck service to all major US cities." If this statement on the "Web page" is highlighted, that means that a click of the reader's computer mouse will take him or her to a new Web page with details. These may include complete schedules and a form to fill out to order a pickup and delivery.

Some Web pages even offer ways to make electronic payments, usually through credit cards.

However, the security of money transfers over the Internet is still a major issue. Yet despite concerns with verifiability of financial transactions, electronic commerce over the Web is growing fast. In its second full year of existence, 1994, only some $17.6 million in sales were conducted over the Web. But in 1995, sales reached $400 million. Today, in 1996, the Web is jammed with commercial sites begging for your credit card information.

In addition, the Web is being used as a tool in the distribution of a new form of currency, known as electronic cash. It is conceivable that, if the hurdle of verifiability may be overcome, that electronic cash (often called ecash) may play a major role in the world economy, simplifying international trade. It may also eventually make national currencies and even taxation as we know it obsolete.

Examples of Web sites where one may obtain ecash include the Mark Twain Bank of St. Louis, MO (http://www.marktwain.com) and Digicash of Amsterdam, The Netherlands (http://www.digicash.com).

The almost out-of-control nature of the Internet manifests itself on the World Wide Web. The author of a Web page does not need to get permission or make any arrangement with the authors of other Web pages to which he or she wishes to establish links. Links may be established automatically simply by programming in the URLs of desired Web page links.

Conversely, the only way the author of a Web page can prevent other people from reading it or establishing hypertext links to it is to set up a password protection system (or by not having communications links to the rest of the Internet).

A problem with the World Wide Web is how to find things on it. Just as anyone may hook a new computer up to the Internet, so also there is no central authority with control or even knowledge of what is published where on the World Wide Web. No one needs to ask permission of a central authority to put up a Web page.

Once a user knows the address (URL) of a Web page, or at least the URL of a Web page that links eventually to the desired page, then it is possible (so long as communications links are available) to almost instantly hook up with this page.

Because of the value of knowing URLs, there now are many companies and academic institutions that offer searchable indexes (located on the Web) to the World Wide Web. Automated programs such as Web crawlers search the Web and catalog the URLs they encounter as they travel from hypertext link to hypertext link. But because the Web is constantly growing and changing, there is no way to create a comprehensive catalog of the entire Web.

Email

Email is the second oldest use of the Internet, dating back to the ARPAnet of 1972. (The first use was to allow people to remotely log in to their choice of one of the four computers on which ARPAnet was launched in 1971.)

There are two major uses of email: private communications, and broadcasted email. When broadcasted, email serves to make announcements (one-way broadcasting), and to carry on discussions among groups of people such as our Happy Hacker list. In the group discussion mode, every message sent by every member of the list is broadcasted to all other members.

The two most popular program types used to broadcast to email discussion groups are majordomo and listserv.

Usenet

Usenet was a natural outgrowth of the broadcasted email group discussion list. One problem with email lists is that there was no easy way for people new to these groups to join them. Another problem is that as the group grows, a member may be deluged with dozens or hundreds of email messages each day.

In 1979 these problems were addressed by the launch of Usenet. Usenet consists of news groups which carry on discussions in the form of "posts." Unlike an email discussion group, these posts are stored, typically for two weeks or so, awaiting potential readers. As new posts are submitted to a news group, they are broadcast to all Internet hosts that are subscribed to carry the news groups to which these posts belong.

With many Internet connection programs you can see the similarities between Usenet and email. Both have similar headers, which track their movement across the Net. Some programs such as Pine are sent up to send the same message simultaneously to both email addresses and newsgroups. All Usenet news readers allow you to email the authors of posts, and many also allow you to email these posts themselves to yourself or other people.

Now, here is a quick overview of the Internet basics we plan to cover in the next several issues of Guide to (mostly) Harmless Hacking:

1. Unix
We discuss “shells” which allow one to write programs (“scripts”) that automate complicated series of Unix commands. The reader is introduced to the concept of scripts which perform hacking functions. We introduce Perl, which is a shell programming language used for the most elite of hacking scripts such as SATAN.

3. TCP/IP and UUCP

This chapter covers the communications links that bind together the Internet from a hackers' perspective. Extra attention is given to UUCP since it is so hackable.

4. Internet Addresses, Domain Names and Routers

The reader learns how information is sent to the right places on the Internet, and how hackers can make it go to the wrong places! How to look up UUCP hosts (which are not under the domain name system) is included.

5. Fundamentals of Elite Hacking: Ports, Packets and File Permissions

This section lets the genie of serious hacking out of the bottle. It offers a series of exercises in which the reader can enjoy gaining access to almost any randomly chosen Internet host. In fact, by the end of the chapter the reader will have had the chance to practice several dozen techniques for gaining entry to other peoples' computers. Yet these hacks we teach are 100% legal!

__________________________________________________
Want to share some kewl stuph with the Happy Hacker list?  To send me confidential email (please, no discussions of illegal activities) use . Please direct flames to dev/null@cmeinel.com. Happy hacking!

© 1996 Carolyn P. Meinel. You may forward the GUIDE TO (mostly) HARMLESS HACKING as long as you leave this notice at the end..


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