Chapter 4: Configuring Internet Access
Exam Objectives
Getting connected to the Internet
Working with TCP/IP technologies on the Internet
Configuring Internet settings with Internet Explorer
Working with firewall devices to protect your computer
In this chapter, you examine how to connect to the Internet and discover some of the basics of how it works. This chapter is chock-full of terminology that you need to be familiar with as well as different methods available to access the Internet. Because the Internet now plays such an integral part in many people’s lives, as a CompTIA A+ Certified Professional, you should be familiar with where it came from — and how to connect to it.
Understanding the Internet
The Internet was originally created and implemented by DARPA (Defense Advanced Research Projects Agency; often referred to as just ARPA) in response to a U.S. Department of Defense (DoD) request. At the time, the DoD was concerned about its centralized communications network. Most communications were relayed through a central computing system or hub, and damage to that system could stop computer communication. To avoid this problem, the DoD gave ARPA the responsibility of devising a new system.
The first thing that ARPA had to do was to create communication protocols that would allow computers to talk to each other in a new and nonstandard, decentralized manner, and ARPA needed a small network on which it could test and develop the new protocols. It eventually interconnected four hosts, which formed the start of the ARPANET.
ARPANET (and now the Internet) was defined by a series of standards that are currently being put forth by the Internet Architecture Board (IAB), which represents the governing body of the Internet. These Internet standards are defined by IAB but are discussed in RFC (Request for Comments) documents. The first RFC defined how the initial hosts on the ARPANET would send to and receive data from each other.
All RFCs — currently, more than 5,500 — are available from www.ietf.org. Technologies in RFCs sometimes make it into STD (Standards) documents, of which there are currently fewer than 70. An index of the standards can be found at
www.rfc-editor.org/std-index.html
During the 1970s, protocols were created and evolved, allowing for support of more and more services over ARPANET, and the number of members continued to increase. Most ARPANET members were locations that did research for ARPA — mainly universities and research centers. Terminal connections via Telnet were created, as was the fashion of using the @ character (meaning at) as a separator between username and mail server for e-mail addresses. Emoticons were soon to follow, starting with joke markers, such as -) (tongue in cheek) in the late 1970s, and the first Smileys :-) in the early 1980s.
During the 1980s, several major events occurred:
TCP/IP became the standard communication protocol.
The term Internetwork, truncated to just Internet, became the name of the network.
Many operating systems standardized on TCP/IP.
The National Science Foundation took over management of the Internet.
The IAB was established to manage accepted standards on the Internet.
Also during 1980s, other countries started to join their national networks to the U.S. Internet, making it a true world-wide network. Several new application protocols were created to allow communication, such as NNTP (Network News Transfer Protocol) and IRC (Internet Relay Chat). This was also the decade that saw the first Internet worm released — namely, the Morris Worm, which was named for its creator.
TCP/IP — Transmission Control Protocol/Internet Protocol — is the protocol suite that is used by the Internet, but it comprises many different protocols that function at different levels of the network model. There are network protocols, transport protocols, and application protocols. In fact, the number of protocols is limitless. Many key protocols are discussed in earlier chapters (see Book VII, Chapter 3, and Book VIII, Chapter 1), but this chapter covers some of the others, such as
SMTP: Simple Mail Transport Protocol
POP3: Post Office Protocol version 3
HTTP: HyperText Transfer Protocol
FTP: File Transfer Protocol
IMAP: Internet Message Access Protocol
TCP/IP — the communication protocol used on the Internet — is actually a suite of protocols that covers all aspects of the communication process.
In the 1990s, the biggest single change to the Internet was caused by CERN (Conseil Européen pour la Recherche Nucléaire, or the European Council for Nuclear Research) developing a new method of linking documents stored on different servers. CERN modified SGML (Standard Generalized Markup Language), created a new language called HTML (HyperText Markup Language), and named the technology the World Wide Web. This single technology changed the face of the Internet, which went from a method of linking documents for information to a conduit for shopping, personal expression, media production and delivery, and untold other things.
Since 2000, technologies created for and used over the Internet have steadily risen to allow for remote access, collaboration, file sharing, streaming media, and VoIP (Voice over Internet Protocol). Government services and major corporations have all embraced the Internet as a major method of communicating with clients, and people in general have changed how they communicate, using instant messaging and social networking sites. Internet gaming has become popular, with software companies generating steady revenue streams from monthly gaming fees. Today, if the Internet disappeared, many people would be at a loss to figure out how to communicate with one another.
Many countries now offer public access terminals for the Internet in convenient locations, such as libraries. Users can connect to the Internet through these public access terminals, Wi-Fi hot spots, and any number of other methods. Some cities have gone so far as to set up city-wide public wireless access.
The Internet has evolved from something small to become what we now know as the Internet. Even today, the Internet is constantly evolving, with new protocols created daily and new uses for the technology limited only by imagination. I wonder what the Internet will look like by the end of the next decade.
Using an ISP
Essentially, the Internet is a large, routed network, with technology similar to the networks found in a large corporation. The main difference between the Internet and a corporate network, though, is that all the small networks that make up the Internet are conjoined, but corporate networks are kept private. To access the Internet, you must access one of the networks that are connected to the Internet. These networks are run by Internet service providers (ISPs), which are in place simply to allow you to access the Internet. Figure 4-1 illustrates how a connection to the Internet works. In order to get connected to the Internet, the following would occur:
1. Connect your computer to your ISP’s network by using a communication device, such as a modem or router.
2. The ISP connects its network to its provider’s network by using a router and a communication link, such as a leased Telco line.
3. Eventually, a connection is made to part of the Internet backbone, which allows connections to every network that is connected to the Internet.
Figure 4-1: How you connect to the Internet.
In addition to connection services, most ISPs provide other services, such as
E-mail addresses and message space on servers
Local news servers that replicate Usenet news groups
These are discussion groups for various topics in a Bullet1in board format.
Web page storage space
Most Internet access service used to be provided over standard modems or through a dedicated link, such as 56K frame relay. Dialup access to the Internet is giving way to permanent connections, such as cable and ADSL (Asynchronous Digital Subscriber Line), which offer great improvements in access speed.
Working with an ASP
The acronym ASP is used for two different technologies: Active Server Pages and application service providers.
Application service providers host servers for their clients. These servers may be database or mail servers, and may be shared or dedicated to a single customer. In either case, the server’s hardware and software are maintained by someone other than the customer. This is a useful setup for smaller organizations because they do not have to invest in large servers or personnel to manage them. Rather, they basically rent space on them.
You will not be tested on ASP for the exam. I include this information, though, because application service providers are sometimes considered to be a type of ISP, although they usually offer only data and content services and not connection services.
Understanding Internet Protocols
When many people think of protocols and computers, network and transport protocols come to mind. These two types of protocols seem to get all the credit. Network and transport protocols are the network communications components that connect your computer to a network, sending and receiving bundles of data between hosts. They include such protocols as TCP/IP, IPX/SPX, and NetBEUI.
Generically, a protocol is a set of standards or conventions that are followed when formatting data to be used for electronic communications, and data transfer is just one level in the electronic communications model. This definition of protocol is not limited to data transfer, and a number of protocols work at other layers: most notably, the application layer. Application layer protocols establish a standard or format for data that is to be communicated. These protocols are so-named because they are the first layer to which programs or applications on a computer (as well as the server components) communicate.
TCP/IP
TCP/IP is not a protocol in and of itself; rather, it is a suite of industry-standard protocols. It is a routable wide area network (WAN) protocol that shares many similarities with Novell’s IPX/SPX, both of which are covered in Book VIII, Chapter 3. One main difference, however, between IPX/SPX and TCP/IP is that TCP/IP is an open (free) protocol, and IPX/SPX is proprietary. TCP/IP standards are developed, established, and used by the computing community itself. Novell is responsible for the development and standards for the IPX/SPX protocol.
Figure 4-2 shows some protocols used as part of the TCP/IP protocol suite and what each protocol is responsible for. At the lowest level, IP offers best-effort delivery services. That is, IP attempts to deliver all network packets to the best of its ability. It also processes any errors reported back from routers. At the next level, TCP offers guaranteed delivery services, and UDP (User Datagram Protocol) offers best-effort delivery services.
Session services for TCP/IP are offered by either NetBIOS over TCP/IP (NetBT) or Windows Sockets (Winsock). The NetBIOS session interface is used by all Microsoft network clients, including Windows 9x and Windows NT 4.0, as their method of communicating with Microsoft servers on the network. Windows 2000 and later Microsoft OSes use the NetBIOS interface for backward compatibility, preferring to make connections using the Winsock interface. The Winsock interface is Microsoft’s implementation of BSD sockets, which is the primary session interface that has been used on all Unix and Unix-based systems. Because most Internet servers originally ran Unix, the application layer protocols (such as HTTP, FTP, SMTP, and POP3) are all designed to communicate through the socket-based session interface.
Figure 4-2: TCP/IP uses many protocols at different layers to accomplish its task.
E-mail is one of the applications that made the Internet indispensable to most people. E-mail was an early tool for ARPANET that enabled users to communicate ideas and concepts to colleagues many miles away. E-mail allows for individually addressed text messages to be transferred over the Internet and delivered directly to the targeted recipient(s). Compared with conventional land-based mail (snail-mail), these transfers are instantaneous.
Attachments that accompany e-mail messages are converted into a text stream by means of encoding. MIME (Multipurpose Internet Mail Extensions) is currently one of the most popular encoding methods on the Internet. Other popular encoding formats include BinHex and UUencode. Encoding, which converts binary data containing 8 bits per byte to ASCII or text data with 7 bits per byte, enables binary attachments to be sent over the text-based e-mail network. When you receive attachments, they must be decoded by your e-mail program. If your e-mail program cannot do this, however, you have to use a third-party application to decode the files.
When it comes to reading your e-mail, you can choose from a wide variety of applications. In fact, the list of clients is extensive, including command line clients, Windows-based clients, and Web-based clients.
SMTP is the Internet protocol used to send e-mail.
POP3 and IMAP are the Internet protocols used to receive e-mail.
Some e-mail clients may support more than one access protocol. SMTP and POP3 are the most commonly used protocols although IMAP is increasing in popularity on private networks. Figure 4-3 shows how these three protocols fit together, and the following sections discuss them in more detail.
Figure 4-3: Where mail protocols are used.
SMTP
Simple Mail Transport Protocol (SMTP) is a mail delivery protocol, used to transfer mail messages from your mail client to a mail server. After the mail message is in queue on the server, SMTP is also used to transfer the message to the mail server that is responsible for the target domain, such as @mailtarget.loc. The primary goal of SMTP is to get the mail messages to the targeted server.
POP3
Post Office Protocol version 3 (POP3) is a client access protocol, used to access or retrieve mail from a server. POP3 does not send e-mail — that is the responsibility of the SMTP. When you configure your e-mail client, you will configure it with the pair of servers: POP3 for downloading or reading, and SMTP for sending (see the preceding section). POP3 clients usually download all mail messages for their servers and delete the mail from the server. This action then leaves the mail only on the client computer.
IMAP
Internet Message Access Protocol (IMAP) is also a client access protocol for mail. As an IMAP client, you retrieve a list of messages that exist on the mail server and download only messages that you want to read. Any downloaded messages are also left on the server. Changes to your mail files locally can also be replicated to the server. Because you can download all messages, you can work entirely offline. If you delete messages while working offline, those deletions will be replicated to the server the next time you connect, in turn deleting the messages on the server.
Configuring an e-mail client
When you want to read e-mail, you must first configure an e-mail program on your system. This e-mail program is also known as an e-mail client because it connects to the service provider’s e-mail server and downloads the e-mail to your system using POP3 or IMAP.
Windows systems come with Outlook Express, which you can configure to connect to the ISP’s e-mail server. Windows Vista and Windows 7 use Windows Live Mail.
To make this connection with an e-mail client, you need the following information:
Username: The username is provided by the service provider and most times may be the first part of your e-mail address. For example, the account [email protected] would most likely have a username of bobsmith.
Password: The password is supplied by the ISP when it created your account. Make sure that you change that password so that no one can easily guess the password.
SMTP Server (outgoing server): This is the address of the server that will send e-mails for you. You can input the IP address or the FQDN of the server, such as mail.myisp.com or smtp.myisp.com.
POP3/IMAP Server (incoming server): This is the address of the server that you download your e-mails from. It is most likely the same system as the SMTP server that sends your e-mails. Again, you can use the IP address or the FQDN of the server, such as mail.myisp.com or smtp.myisp.com.
The following steps demonstrate how to configure the e-mail client software on a Windows XP computer:
1. Launch Outlook Express by choosing Start⇒All Programs⇒Outlook Express.
2. Choose Tools⇒Accounts.
3. Choose Add⇒Mail to create a new mail account, or edit/verify an existing mail account by selecting it and choosing Properties.
I have chosen Add Mail for this walk-through.
4. Type the name of the mail account to create; then choose Next.
For my account, I am typing Glen E. Clarke.
5. Type your e-mail address; then choose Next.
I am typing [email protected].
6. Specify whether you are using POP3 or IMAP to connect to the mail server and download the mail.
You will most likely use POP3.
7. Type the address of your SMTP server and POP3 server as shown in Figure 4-4; then choose Next.
You are asked for your account name and password. You will need to get this information from the e-mail provider.
8. Enter your account name and password. Choose Next and then Finish.
Configuring the mail settings on Windows 7 is similar, but you must install the Windows Live Essentials to get a mail client installed first. After the mail client is installed, it can then be configured with an account including the SMTP and POP3 mail server settings.
Figure 4-4: Configuring SMTP and POP3 server settings.
When configuring e-mail software, you may need to specify other configuration settings depending on the software you are configuring. The following are some common settings that may need to be configured:
Port and SSL settings: You may need to configure the e-mail client port for nonsecure and secure (SSL) e-mail:
• For nonsecure e-mail, the default port is 110 for POP3 and 143 for IMAP.
• For secure (SSL) e-mail access, the ports are 995 for secure POP3 over SSL and 993 for secure IMAP over SSL.
Exchange: You may need to connect your e-mail software to the company Exchange server. Microsoft Exchange Server is the name of the Microsoft mail server product that companies use to host their own e-mail. To connect to the Exchange server from Outlook, you need to specify
• The name of the Exchange server
• The mailbox name you want to connect to
Gmail: Many people are using online e-mail providers such as Hotmail and Gmail to access their e-mail over HTTP. You can configure most e-mail software to connect to the Hotmail or Gmail mailboxes by just typing in the e-mail address of the account.
HTTP mail accounts, such as Hotmail and Gmail, have become increasingly popular. These accounts leave their mail messages on the server in a manner similar to IMAP.
HyperText Transport Protocol
Much older than the Internet, the concept of hypertext has been around since 1945 when Vannevar Bush wrote an article titled As We May Think. The word hypertext was coined in 1965 by Ted Nelson. Hypertext was a means of indexing, or cross-referencing, data found in different documents, allowing users to quickly move to linked documents.
In the early days of the Internet, you could transfer data as files between computers. After being uploaded to the server by the data owner, these files were available for download from those servers, which meant you had to know what files you needed and what servers they came from. Your text files, formatted documents, and graphics could be transferred between computers. After you downloaded the files, they could be opened and viewed, but there was no way to view them in an attractively formatted style in the online environment, especially in a format that was universally accessible. Most formatted documents were created and formatted in proprietary programs like Microsoft Word or Adobe PageMaker — and thus readable only by people who have those programs.
To address the problem of knowing which servers you were accessing data from, Paul Lindner and Mark McCahill (University of Minnesota) came up with an idea that became the Gopher protocol in 1991. Gopher used hypertext concepts and allowed you to place a pointer on your server that would connect people to specific directories on other servers elsewhere on the Internet. This made browsing information scattered across servers very easy because switching between servers became completely transparent. Gopher became the most popular tool for downloading files and data from the Internet.
At the same time Gopher was being developed, the researcher Tim Berners-Lee at CERN was working on a hypertext system he called World Wide Web (choosing that name over The Information Mesh). This system implemented a protocol called HTTP, which allowed for transparent linking of documents between servers. This capability was possibly thanks to the new HyperText Markup Language (HTML) that was being used for World Wide Web data.
The tool that accesses HTTP servers and HTML files is, of course, the Web browser. A Web browser retrieves the files from the server, displays the formatted document, and links to other servers as required. Early Web browsers displayed text and images as separate but linked documents, so you could view images if you followed an image link. The Web really took off in 1993 when Marc Andreessen of the National Center for Supercomputing Applications (NCSA) released NCSA Mosaic and offered something the Gopher and other Web browsers lacked — the capability to view text and graphics mixed together in a single frame. Internet users flocked to this new technology that gave their data the same appearance as the paper-bound copies. Figure 4-5 shows a formatted document in a Web browser.
Figure 4-5: Web browsers let you retrieve data from a server using HTTP.
HyperText Markup Language
HyperText Markup Language (HTML) is a form of SGML that offers a universal way to format documents. Standards for SGML are more complex than for HTML. SGML is actually a method of creating interchangeable, structured documents so that they can be universally accessed from different types of systems. SGML can take data from a variety of sources (such as word processors and graphics applications) and join them as a single structured document by using Document Type Definitions (DTDs). Different DTDs are identified in a document with the aid of markups or tags, which show or identify the divisions or sections.
HTML is actually just a DTD that is one of the many small parts of SGML. With the simple initial requirements for formatting of documents, Tim Berners-Lee decided that keeping the formatting language simple was the best course of action for the Web, so HTML was adopted in favor of SGML.
HTML files are text or ASCII files, but they contain formatting codes that are embedded in the text. The Web, or HTML, page displayed in Figure 4-5 was generated with the following script (Listing 4-1).
Listing 4-1: Script used to create web page shown in Figure 4-5
<html>
<head><title>A+ Sample Web Page</title></head>
<body>
<h1>Web Page Basics</h1>
<p>The web page is the basics of HTML.</p>
<p>It does require that somebody has to do a lot of typing to create the web content. This content has formatting tags embedded in the content, which suggest how to draw items on the page. The decision of how to actually draw or render the content is actually made by the client browser.</p>
<hr>
<img src=”photo.jpg” width=”320” height=”176” align=”right”>
Some different client browsers include:
<ul>
<li>Internet Explorer
<li>Mozilla Firefox
<li>Cello
<li>etc
</ul>
</body>
</html>
Early HTML files were saved with either the .html or .htm extension (for MS-DOS’s 8.3 character filename compatibility), but now may have a variety of extensions (such as .php or .asp) because of various scripting languages being used to build dynamic Web pages.
HTML has gone through many revisions; the last revision was version 4. Changes are being made to HTML with the integration of XML (Extensible Markup Language). XML, which adds functionality to support database data exchange, is designed to transfer not only sections of data from a database but also its structure. XML has become very popular and is a huge Internet buzzword.
As I mention, XML has been rolled into the HTML standard, forming the XHTML (Extensible HyperText Markup Language) standard, so HTML is now XHTML. The current version of XHTML is 1.0, with 2.0 just around the corner with a working draft already in place. For more information about XML, HTML, and XHTML standards, visit the World Wide Web Consortium at www.w3.org.
HTTPS and SSL
HTTPS is a secure version of the HyperText Transport Protocol. When you use HTTP, all communication between you and the server is in cleartext, so anyone can easily read all that communication. HTTPS uses SSL (Secure Sockets Layer) or its successor, TLS (Transport Layer Security), to provide authentication and encryption services.
HTTP communicates with a server on TCP port 80, and HTTPS uses TCP port 443.
To implement SSL, a Web server needs to have a security certificate installed to verify its identity for you. When you are confident that the server is who it says it is, you can then carry out secure and encrypted data transfers with it.
Early SSL used 40-bit encryption keys, which were not secure and were easy to break. Current SSL uses 128-bit or larger keys and is very hard to break, making data protected with SSL very secure.
Do not confuse the flurry of H-based acronyms used for the World Wide Web. HTML is the document formatting; HTTP is the cleartext transfer protocol that uses TCP port 80; and HTTPS is an encrypted transfer protocol — secured by SSL or TLS — which uses TCP port 443.
File Transfer Protocol
The first scientists using the Internet established early during the evolution of the Internet that there would have to be some format to allow for the transfer of data (as opposed to text messages) across the Internet. The solution was File Transfer Protocol (FTP), which allows files to be uploaded and downloaded from servers. FTP requires an accessible directory or folder, a server-side service (or daemon), and a client.
There are a large number of FTP clients to choose from, ranging from command line–based to graphical (like FileZilla or WinSCP). Figure 4-6 shows some different FTP clients available on the Windows platform. If you regularly work with FTP, then you will likely want to learn one of these clients, rather than relying on the FTP features that are included with most Web browsers.
Figure 4-6: Choosing the right client for the job is important.
Because of the method that traditional FTP servers used, they were not Network Address Translation (NAT) friendly when the server was placed behind a NAT gateway or firewall. That led to the creation of passive FTP, which changes the orientation of connections in the FTP process. To make use of a passive FTP server, your FTP client has to support and be configured to use passive FTP.
Because the FTP authentication and data-transfer process is all in cleartext or unencrypted data packets, a new protocol has been created — Secure Copy Protocol (SCP) — which transfers files over ssh (covered later in this chapter) on TCP port 22. SCP has been replaced for most people with Secure File Transfer Protocol (SFTP), which also uses ssh and is a more feature-rich protocol.
Command shells
A shell is an interface for users to connect to. When you log onto your Windows computer, your desktop environment is generated by explorer.exe. On Unix and Linux servers, if administrators choose not to load a graphical environment, the shell application would be command line driven, usually with some variant of bash (Bourne-Again Shell). Because most Unix or Linux server administration can be done from the command line, remote shell access to a server is very important, both from the aspect of remote administration and for security. In addition to these servers, many network devices (such as routers, switches, and hardware firewalls) support a remote management command shell. The two most common methods of connecting to these command shells are telnet and ssh.
Windows Server 2008 has an installation method called Server Core Installation that does not install the default GUI (explorer.exe) but rather allows all administration to be performed via a command prompt or using GUI tools remotely. This type of installation reduces maintenance, the attack surface, and management; and also uses less disk space.
telnet
telnet, developed in 1969, has been the long-standing standard for remote management, in spite of its long-standing security flaw. The largest single flaw with telnet is that the entire communication process between the client and server takes place in cleartext. For any person in a position to view the raw network traffic, the entire conversation can be viewed, including the logon usernames and passwords. Server administrators moved to newer management technology some time ago, but many hardware manufacturers kept using telnet until fairly recently. Windows includes a default command line telnet application, and you can also get third-party graphical telnet applications that allow you to easily manage multiple sessions or capture log files of sessions.
ssh
ssh, developed in 1995, is short for secure shell. Remote access to a shell on a computer is what ssh is designed to secure, just like the name suggests. In addition to allowing remote shell access to servers, ssh allows for opening secure tunnels, allowing secure access to other systems on a remote network through the tunnel. When working with ssh with the lowest security level, the server uses a certificate to generate initial encryption keys and then encrypt the data stream between the client and server. For stronger security, client certificates can be used for authentication of the client as well as the server using its certificate. Server administrators that dealt with telnet cleartext data for years quickly converted to ssh when it became available, making it the new standard in remote shell access. Some telnet holdouts, like network switch manufacturers, have finally listened to their customers and added support for ssh. It is now prevalent on all systems that traditionally supported telnet. In order to use ssh, you will require a client, such as PuTTY (www.chiark.greenend.org.uk/~sgtatham/putty).
ssh should be considered the minimum connection mechanism for remote devices. telnet, with its cleartext data transfers, should no longer be considered.
Installing and Configuring Browsers
Internet Explorer (IE) is the default Web browser for most Windows computers, partly because it comes installed with that OS. With this boost, Microsoft won the browser wars of the 1990s, which saw the main battle between IE and Netscape Navigator (even though both owed their roots to NCSA Mosaic). Although many different browsers were available in the beginning, these two products quickly rose to the top of the pile and battled it out.
Right around the turn of the century, Netscape released the source code for the core Netscape engine — Mozilla — to the open source community. This powerful engine quickly formed the core of many open source products, and one product — Mozilla Firefox — gained widespread adoption by the open source market. Firefox offers many features not originally included in Microsoft products, such as pop-up blocking and tabbed browsing, plus the ability to choose from thousands of add-ons (extensions) written by the open source community. This product was released at a time when IE was experiencing several security problems, and many people wanted a product that did not suffer from the same problems.
Like with all browser wars (and all wars), products are continually enhanced, and the next version of IE will include many features that have lured people to Firefox. You can find Firefox at www.mozilla.org/firefox, and the latest version of IE is at www.microsoft.com/ie. Both sites have links you can click to download and install the browser, and you have the option each time you start the nondefault browser to set it as your system default browser.
The following sections look at Internet Explorer, although similar settings are available in most Web browsers.
To configure IE settings, open IE and choose Tools⇒Internet Options, which opens the Internet Options dialog box shown in Figure 4-7. This dialog box contains seven tabs, and I discuss each in the following sections.
Figure 4-7: Manage Web browser settings through Internet Options.
Configuring General settings
From the General tab (shown in Figure 4-7), you configure settings for your home page, browsing history (including temporary Internet files), search defaults, and tabbed browsing. The other settings are primarily cosmetic. The settings for temporary Internet files allow you to choose the location of the files, how much space they will take on your hard drive, and your setting for refreshing content from the Web site directly.
Configuring Security settings
From the Security tab, you set security settings for sites in one of four zones. Most sites that you visit will fall into the Internet Zone, and the Local Intranet, Trusted Sites, and Restricted Sites affect only sites that you specifically enter onto those lists. Each zone can have different security settings. And, for each zone, you can choose from one of five security levels or specify your own custom settings. The five built-in levels are High, Medium-High, Medium, Medium-Low, and Low, although for the Internet setting, you can choose from only the three highest settings.
Click the Custom Level button to see exactly what settings are enabled. The settings in the resultant dialog box, also shown in Figure 4-8, allow you to set IE to handle a variety of components that may be embedded in Web pages. For example, you can have IE disable, enable, or prompt you when it encounters certain components on Web sites, such as .NET Framework–reliant components, ActiveX controls and plug-ins, downloads (for files and fonts), scripting (including ActiveX scripting and Java applets), user authentication (often done automatically in the background), and a slew of user interface options.
Figure 4-8: Security settings in Internet Explorer can make the browser much safer.
Configuring Privacy settings
The IE Privacy tab, which deals with cookies and pop-ups, works in a similar fashion to the Security tab. Here, you can configure settings for cookies on a per-site basis as well as configuring general settings by using either the slider for levels from Allow All Cookies to Block All Cookies (with four levels in between) or by clicking the Advanced button and then customizing your cookie settings.
Cookies — settings that are stored on your computer by your Web browser. When you return to the Web server later, these settings are sent back to a Web server. Web sites use cookies to track users, especially if the site uses a shopping cart–transaction system. Shopping carts allow you to browse a catalog, select items you want, and check out. This mechanism is not only used at shopping sites but also at download sites, where you can select multiple files and download them all in one action at the end of your visit.
In addition to shopping carts, many sites will store a unique ID in a cookie on your computer to track your return to the site. In some cases, the IDs are used to set user preference or to track unique visitors. Cookies are stored in text files on your system and generally use very little space. When visiting one Web site, you might see content that comes from another Web server, which is the case with most of the banner ads that appear on Web sites. If this other Web server attempts to have a cookie stored, it is called a third-party cookie. You might want to block third-party cookies or all cookies if you are concerned about having companies track your activity on their Web sites.
If you choose to block pop-ups, click the Settings button to configure settings as well as a list of sites that are allowed to use pop-ups.
Configuring Content settings
From the Content tab, you can enable the Content Advisor, which makes use of voluntary tags that Web content developers can include on Web pages. These tags rate the level of language, nudity, sex, and violence found on the page. With the Content Advisor enabled, you can block content that is above the customized configured level. The Certificates section allows you view and modify (import and export) SSL certificates that IE uses. The Personal Information section allows you to modify the AutoComplete settings that are used on forms you encounter on Web sites.
Configuring Connections settings
A proxy server acts as a middleman when you request information from the Internet, allowing network administrators to restrict access through the network firewall, as well as audit what Web sites network users are going to. If you need to use a proxy server to browse the Internet, you can use the proxy settings to configure your access to proxy servers.
Proxy settings, found on the Connections tab, can be configured for each of the dialup settings individually or for your LAN connection. Both have similar settings, so I discuss the LAN settings, which you reach by clicking the LAN Settings button. The settings are shown in Figure 4-9 and include automatic proxy detection and configuration, which requires specific configuration settings on your network.
In addition to this setting, you can manually configure a proxy server address and port for your particular network and use that same server for http, https, ftp, gopher, and socks. The socks setting allows you to proxy protocols other than the default ones that are listed. You might use socks to proxy IRC or POP3. As with most cases, you can also configure a list of servers that are exceptions to using the proxy server, which might be the case when you have servers on your internal network that you don’t want to use a proxy server for.
Figure 4-9: If you are using proxy settings, you might need to regularly enable or disable the settings.
Configuring Programs settings
From the Programs tab, you can specify which programs to use for different types of Internet services, such as HTML editing, e-mail, and newsgroups. In addition, you can configure and manage IE add-ons, which are third-party components loaded automatically by IE.
Working with Advanced settings
The last tab in Internet Explorer’s Internet Options dialog box is the Advanced tab. It has a variety of settings you can modify (by enabling or disabling features and functions) how IE works. These settings are Accessibility, Browsing, HTTP 1.1, Java, Multimedia, Printing, and Security. See Figure 4-10.
Figure 4-10: Security Settings are just one of the types of Advanced Settings.
Using the Internet
When using the Internet, be aware where you are going when you click links on your Web browser. This section looks at what makes up the parts of a URL (Uniform Resource Locator), the string of text that appears on the address line in IE. The standard URL has an access method, a server name, and the path to a file or directory on the server. A typical URL resembles the following:
http://www.edtetz.net/sample_files/default.htm
In this example, http: represents the access method, //www.edtetz.net represents the name of the server being contacted, /sample_files represents the directory being navigated to, and /default.htm represents the file being requested. All URLs follow the same basic structure, but if you leave out one part of it — such as the document name — you will be given the default document for that directory or server.
Access methods
Table 4-1 summarizes some of the access methods for resources on the Internet. These access methods can be specified from the command line or from within a Web browser.
Table 4-1 Access Methods
|
Access Method |
Description |
|
|
Used to access Web content on servers |
|
|
Used to secure |
|
|
Used to copy files to and from remote servers |
|
|
Used to access remote terminal services with a remote server |
|
|
A hyperlink protocol similar to |
|
|
Activates the local e-mail client to send a message to the address specified in the server portion of the URL |
|
|
Used to access files on an NNTP server or Usenet newsgroup |
Domain names and Web sites
Every computer on the Internet has a unique IP address. This address enables a computer to find and establish communications sessions with any other computer — that is, as long as you know the IP address of the computer you want to connect to.
Every IP address is potentially a 12-digit number. Because every IP address could be a 12-digit number — and because most people cannot remember hundreds of 12-digit numbers — the domain name system (DNS) was established in 1984. With DNS, you specify a name, and the DNS resolver or client on your computer will look up the required address for you on a DNS server.
Because each server could never be able to hold the names of all the computers on the Internet, DNS servers split up the job. Each server is responsible for knowing only a small number of computers, but the servers know how to find other servers. Figure 4-11 illustrates how the DNS is structured. At the top of the structure is the root (.) domain, which knows about all the servers that manage the top-level domains (TLDs). TLDs include com (commercial), org (organization), mil (military), edu (education), gov (government), and net (network), as well as a two-letter domain for every country in the world, such as au (Australia), us (United States), uk (United Kingdom), and de (Germany). The servers at the top level know about the servers that are responsible for the next level down, and so on.
Figure 4-11: Overview of the domain name system.
Restrictions around top-level domains have become more relaxed. As such, the Internet Corporation for Assigned Names and Numbers (ICANN) has registered several new TLDs, such as travel (travel industry), name (personal names), museum (museums), mobi (mobile products and services), jobs (HR related), info (informative Web sites), and aero (air transportation and aerospace; maintained by Internet Assigned Numbers Authority [IANA]). There are also misused TLDs, such as ws (officially for the country of Western Samoa, but often used for personal Web sites) and tv (officially for the country of Tuvalu, but often used for television-related sites).
DNS is a global directory that allows friendly names to be resolved to IP addresses. Without this function being performed, you would have to know every server’s IP address.
Here’s how it all works in real life. Say you want to connect to a server with a DNS name of www.edtetz.net. Your DNS client checks against your local server to see whether it knows the IP address for that DNS name. Even if your server is not the owner of that DNS name, it may have looked it up before and have the information cached. If the information is not cached on the local server, your server forwards the request to one of the root-level servers, which directs it to the .net server, which directs it to the edtetz server, which then looks up the www record.
This system gives your browser the capability of finding any computer on the Internet with a name registered with DNS. Many people register their servers by the type of service that they offer, such as ftp.edtetz.net, smtp.edtetz.net, pop3.edtetz.net, or mail.edtetz.net. HTTP allows you to place links on any server to any other server on the Internet, which allows you to have a very complex path configured to lead people through the Internet. Because this path is web-like, the interconnection of HTTP servers is referred to as the World Wide Web (www). www is the standard name that is given to the HTTP or Web servers on the Internet.
When you connect to a server, the URL might have a path listed beyond the root directory, or it might have the complete path to a file on the server. If no filename is given, the Web server usually displays a default document for that directory, such as default.htm or index.htm. If no default document exists for that directory and the server allows for viewing the directory listing, you will see a list of filenames found in the directory, with each filename being a link to the file. When no other condition is met, the server returns an Object not found or 404 error message.
Ways to Access the Internet
In addition to dialup connections, many other types of connections can connect you to the Internet, and some of these connection types might be available in your area from local Internet service providers (ISPs). Some of these are used for home connections, and others are used primarily for connecting LANs to the Internet:
Dial-up
Cable
DSL
ISDN
T1/T3
Fiber
Satellite
Wireless
Line-of-sight wireless Internet service
Cellular (mobile hotspot)
WiMax
The following sections take a closer look at each of these Internet connection types.
Dial-up
Good-old reliable dialup has remained a true friend of remote access and access to the Internet for years. For years, dial-up was the method available to most users, and dialup access was much better than no access. Dial-up is still a standard way to connect to the Internet in many markets in which faster alternatives do not exist. The listed data rate for dialup connections is 56 Kbps.
Cable
Cable connections implement a cable modem in your home or office that takes a digital network signal from your network card and translates (modulates) it into an analog broadband signal. This signal is then passed on to the cable network. Cable companies usually offer transmission speeds between 4 and 30 Mbps to their customers although actual speeds vary. This signal runs over existing cable, using previously unused signal areas of the medium. When using cable, you are on a shared medium with other users until your connection reaches the cable company’s office.
DSL
The most common form of Digital Subscriber Line (DSL) is Asynchronous Digital Subscriber Line (ADSL). An ADSL implementation works similarly to cable (see the preceding section) except that the device you have in your home or office takes the digital signal from your network card and passes it to a phone line. ADSL companies usually offer transmission speeds between 4 and 8 Mbps although actual speeds vary. Cable offers the same transmission speeds going to and from the Internet, but ADSL always has slower upload speeds because the connection is broken into upstream and downstream channels. With ASDL, surfing the Internet and copying large files from Web sites is very fast, but if you want to store a file on a Web site or send e-mails with large attachments, your speeds will be substantially slower. Typical upload speeds for ADSL range between 64 Kbps and 1 Mbps.
The standards for ADSL2 and ADSL2+ have been released, so some vendors may choose to implement these versions of ADSL, allowing for download speeds from 5 to 12 Mbps for ADSL2 and up to 24 Mbps for ADSL2+, although both offer upload speeds only in the 1–3.5 Mbps range. With ADSL, you share the line only until you hit the Telco switching office, which typically must be closer than 3 miles (5 kilometers).
Broadband, high-speed Internet connections through cable, and DSL (of which ADSL is a subtype) have replaced dialup in most regions.
ISDN
Integrated Services Digital Network (ISDN) service comes in two basic forms: basic rate and primary rate.
Basic-rate ISDN: Uses three channels: two 64 Kbps lines for data (128 Kbps) and one 16 Kbps line as a control channel, which is used for establishing and maintaining connections. The data channels are referred to as B channels, and the control channel is referred to as a D channel.
Primary-rate ISDN: Uses twenty-three 64 Kbps B data channels (1.44 Mbps) and one 64 Kbps D channel for control information.
T1/T3
T1 connections offer transmission speeds of 1.544 Mbps over 24 pairs of wires. Each pair of wires can carry a 64 Kbps signal, called a channel. T1 connections can be implemented over copper wire.
T3 connections, on the other hand, require a better medium than copper, such as microwave or fiber optic. They are capable of speeds ranging from 6 Mbps to 45 Mbps.
T1 and T3 are North American standards, and E1 and E3 are similar standards for the European community.
Fiber
Internet access over fiber connections is defined in the Optical Carrier (OC) standards. There are different levels of OC, with OC3 being a common type of Internet connection for large networks as it can carry voice, video, and other data at a transfer rate of 155.52 Mbps.
Internet service providers are now offering fiber to the home so that residential customers can get faster speeds than what are typically offered by DSL and cable connections. Fiber-to-the-home connections can have transfer rates of 150 Mbps!
Satellite
Satellite Internet services come in two basic flavors: one-way with terrestrial return and two-way. Because satellites providing service in most residential areas were designed to send data, the first Internet access over satellites involved downloading from the satellite, but data had to be uploaded via dialup modem. This transmission tied up phone lines, and upload speeds were rather slow. Two-way systems added technology to return a signal to the satellite. Speeds for uploads ran in the neighborhood of only 1 Mbps, but they did free up phone lines. Download speeds over satellite systems rival those of broadband services (such as ADSL and cable). Just like satellite television, satellite Internet is susceptible to the weather and elements.
Wireless
Wireless access to the Internet is provided through standard 802.11 (Wi-Fi) wireless networks, which are set up to provide coverage in prescribed areas. In some locations, wireless access is provided for free to customers of certain businesses, or by a municipal government like Fredericton, New Brunswick (www.fred-ezone.ca).
Sometimes, a company may set up access points in a wide range of locations, offering access through them as part of a subscription service. These wireless access points allow connectivity but only to the company’s Web site to set up an account. After you set up and pay for an account, you can use any of the company’s access points to access the Internet.
For more information about 802.11 networks, read Book VIII, Chapter 2.
Line-of-sight wireless Internet service
A line-of-sight wireless connection is typically used by a company that wants to connect two locations that are spread over a distance to a network. To connect these two locations, the company will typically place large wireless antennas on top of the buildings to allow the antennas to have a clear line of sight between one another with nothing in between to obstruct the wireless signal.
Cellular (mobile hotspot)
Sometimes called wireless, 3G, or 4G, this system makes use of a cellular provider’s wireless network (as opposed to 802.11 networking). To connect to a cellular network, you need a cellular modem for your computer or a cellular router for your network. The cellular modem may be built into your computer, or added as a PCMCIA card or a USB adapter; some phones may even be used as a cellular modem. The benefit of this technology is that you can access the Internet from anywhere your wireless provider has coverage. This is the same technology I cover in Book VIII, Chapter 2 when discussing WAN cellular.
Speeds will vary with each wireless carrier, but you will see rated speeds anywhere from 384 Kbps up to 4.9 Mbps. Speeds are dependent upon the provider providing service on EDGE (Enhanced Data for GSM Evolution), High Data Rate (HDR), EV-DO (Evolution-Data Optimized, or Evolution-Data Only) or 3G (Third Generation) networks. 4G networks began emerging in 2010, driving data speeds to new levels.
WiMax
WiMax is a wireless standard that stands for Worldwide Interoperability for Microwave Access. WiMax is a technology that is designed to cover wide areas like a cellular network, but provide the transfer rate of a wireless network!
Firewalls and Home Routers
When dealing with the Internet, remember that a lot of bad things are out there, and you need protection from the dangers of the world. All software firewalls have the inherent problem that they are software running on the system that they are trying to protect, which is considered bad because software (including firewalls) is more susceptible than hardware firewalls to breaches caused by Trojans or other viruses.
Home routers are typically NAT (Network Address Translation) gateways, which allow multiple computers to share one public IP address. This gives you a layer of additional security because only remote servers or computers are allowed to communicate with your computer after you initiate a connection to the remote computer. When you open the connection to the external server, a temporary channel opens to that server’s IP address, allowing communication.
Some routers have more advanced firewall features to restrict the TCP and UDP ports that are allowed to be used between the two hosts, as well as the ability to filter or restrict access to URLs based on a series of rules. Figure 4-12 shows some of the security settings available on these devices.
Figure 4-12: Typical firewall settings on a home router.
In addition to these hardware residential and SOHO (Small Office/Home Office) routers and firewalls, you can choose from various high-end hardware firewalls. Also, Linux firewalls are available that boot directly from CD-ROM, such as Linux Embedded Appliance Firewall (LEAF), IPCop, or SmoothWall. For many Linux firewalls, you need a low-end computer with two network cards and a CD-ROM drive. For a home or small office, even a Pentium or Pentium II processor (or lower if you can find one) will provide enough power for the job.
You find out more about firewalls in Book IX, Chapter 2. The point is that if you are connecting to the Internet, be sure to have a firewall between you and the outside world!
Getting an A+
This chapter provides a brief history of the Internet and how you connect to it. Other concepts that are covered include
TCP/IP is the suite of protocols used on Internet.
The TCP/IP suite of protocols is made up of other protocols such as FTP, HTTP, telnet, ssh, TCP, UDP, and IP.
POP3, SMTP, and IMAP are the primary protocols used for e-mail.
HTML is the formatting system used for Internet Web pages.
Dialup, ISDN, T1, ADSL, and cable are the main methods used to connect to the Internet.
Prep Test
1 What is the governing body of the Internet?
A 
W3.org
B DodNet
C IAB
D IABnet
2 The TCP/IP networking protocol is composed of how many subprotocols?
A 2
B 5
C 10
D Many, too numerous to list
3 What purpose does MIME serve?
A It is used as an encryption method for e-mail.
B It encodes binary data into ASCII data so that it may be sent through e-mail.
C It is used to convert HTML data into an e-mail format.
D It is used to trap people inside invisible boxes.
4 What protocol is used to send e-mail?
A POP3
B IMAP
C HTTP
D SMTP
5 What protocols are used to read e-mail? (Choose two.)
A SMTP
B POP3
C IMAP
D UDP
6 Which of the following is used to format Web pages?
A HTTP
B WWW
C SSL
D HTML
7 What protocol is used to transfer files to and from a remote server?
A HTML
B POP
C FTP
D SMTP
8 What is the first part of an Internet URL (for example, http://) called?
A Pointer
B Access method
C Control source
D Activation header
9 What system converts names you type in URLs into IP addresses?
A Dual naming standards
B Name resolution server
C Name recognition system
D Domain name system
10 Which of the following are ways to connect to the Internet? (Choose all that apply.)
A HSINet
B Cable
D ISDN
E Wire
F T1
G IAB
Answers
1 C. The Internet Architecture Board (IAB) is the managing body of the Internet. See “Understanding the Internet.”
2 D. Some subprotocols that make up TCP/IP include SMTP, POP3, SNMP, FTP, TFTP, and 500 to 1,000 other protocols. Take a look at “Understanding Internet Protocols.”
3 B. MIME (Multipurpose Internet Mail Extensions) is used to convert binary files into something that can traverse the text-only e-mail system. Peek at “E-mail.”
4 D. SMTP is used to send mail messages over the Internet. Look over “SMTP.”
5 B, C. POP3 and IMAP are used to read mail that is on a mail server. Study “E-mail.”
6 D. HTML (HyperText Markup Language) is the formatting language or standard for Web pages. Refer to “HyperText Markup Language.”
7 C. FTP stands for File Transfer Protocol, which is the traditional method to transfer files to or from a server. Examine “File Transfer Protocol.”
8 B. The first part of a URL represents the access method that is being used to connect to the server. See “Using the Internet.”
9 D. The domain name system resolves requested names into IP addresses to allow you to connect to the named computer. Review “Domain names and Web sites.”
10 B, D, F. Cable, ISDN, and T1 are methods of connecting to the Internet. Check out “Ways to Access the Internet.”