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Each of these services (sometimes referred to by the overused term TCP/IP protocols) operates by using defined ports, requires a special application, and has special settings. You’ll look at all eight of these services and learn how to configure them. As a quick reference, Table 25-1 has some common port numbers CompTIA would like you to know.

Table 25-1 TCP/IP Service Port Numbers

The World Wide Web

The Web provides a graphical face for the Internet. Web servers (servers running specialized software) provide Web sites that you access by using the HTTP protocol on port 80 and thus get more or less useful information. Using Web-browser software, such as Internet Explorer or Mozilla Firefox, you can click a link on a Web page and be instantly transported—not just to some Web server in your home town—to anywhere in the world. Figure 25-31 shows Firefox at the home page of my company’s Web site, www.totalsem.com. Where is the server located? Does it matter? It could be in a closet in my office or on a huge clustered server in Canada. The great part about the Web is that you can get from here to there and access the information you need with a click or two of the mouse.

Although the Web is the most popular part of the Internet, setting up a Web browser takes almost no effort. As long as the Internet connection is working, Web browsers work automatically. This is not to say you can’t make plenty of custom settings, but the default browser settings work almost every time. If you type in a Web address, such as the best search engine on the planet—www.google.com—and it doesn’t work, check the line and your network settings and you’ll figure out where the problem is.

Configuring the Browser

Web browsers are highly configurable. On most Web browsers, you can set the default font size, choose whether to display graphics, and adjust several other settings. Although all Web browsers support these settings, where you go to make these changes varies dramatically. If you are using the popular Internet Explorer that comes with Windows, you will find configuration tools in the Internet Options Control Panel applet or under the Tools menu.

Figure 25-31 Mozilla Firefox showing a Web page

Proxy Server Many corporations use a proxy server to filter employee Internet access, and when you’re on their corporate network you have to set your proxy settings within the Web browser (and any other Internet software you want to use). A proxy server is software that enables multiple connections to the Internet to go through one protected PC, much as ICS works on a home network. Unlike ICS, which operates transparently to the client PCs by manipulating IP packets (we say that it operates at Layer 3—the Network layer in the OSI model—see Chapter 23, “Local Area Networking”), proxy servers communicate directly with the browser application (operating at Layer 7, the Application layer). Applications that want to access Internet resources send requests to the proxy server instead of trying to access the Internet directly, both protecting the client PCs and enabling the network administrator to monitor and restrict Internet access. Each application must therefore be configured to use the proxy server. To configure proxy settings in Internet Explorer, choose Tools | Internet Options. Select the Connections tab. Then click the LAN Settings button to open the Local Area Network (LAN) Settings dialog box (Figure 25-32).

Figure 25-32 The LAN Settings dialog box

Note that you have three options here, with automatic detection of the proxy server being the default. You can specify an IP address and port for a proxy server by clicking the third checkbox and simply typing it in as shown in Figure 25-32.

In some cases, companies have different proxy servers for different programs, such as FTP. You can enter those proxy addresses by clicking the Advanced button and entering the individual addresses. You can also add addresses that should not go through the proxy servers, such as intranet sites. These sites can be added in the Exceptions box