Configuring a Peer-to-Peer Network

When you're sure that the physical connection between your computers is set up correctly, you're ready to configure Windows XP. With today's Plug and Play network cards and with all the needed software built into Windows, this configuration is a snap.

If your computer is part of a Windows XP/200x Domain network, which will often be the case in a corporate setting, skip ahead to "Joining a Windows Domain Network." Otherwise, you have two choices for configuring your network software: You can make the settings manually, or you can let the Network Setup Wizard do the work for you.

NOTE

On a peer-to-peer network, if you want to share or use shared files or printers, you must run the Network Setup Wizard at least once. Windows XP's networking features are initially disabled in order to protect you from Internet hacking. The wizard enables networking after ensuring that your Internet connection is secure.

If you want to set up your network manually, you still must run the wizard first, and then go through the network settings.

Configuring the TCP/IP Protocol

After your network adapters are all installedand, if you're using a wired network, cabled togetheryou need to ensure that each computer is assigned an IP address. This is a number that uniquely identifies the computer on the network. There are three ways that these numbers can be assigned:

• If the network has a computer that uses Windows Internet Connection Sharing to share an Internet connection, or if there is a hardware internet sharing router, or if you are on a corporate LAN running Windows 200x server, each computer should be assigned an IP address automaticallythey're doled out by the Dynamic Host Configuration Protocol (DHCP) service that runs on the sharing computer or in the router. This is why I recommend using a router even if you aren't setting up a shared Internet connection.

• Each computer can be given an address manually, which is a called a static address as opposed to dynamic (automatic).

• If no static settings are made, but there is no DHCP server on the network, Windows will automatically assign IP addresses anyway. However, while the network will work, this is not an ideal situation, and can slow Windows down. I'll talk about this problem later in the chapter under "Configuring Network Components."

If you're setting up a new computer on an existing network, just use whatever scheme the existing computers use; check their settings and follow suit with your new one. The following procedures will show you how. If you're setting up a new computer, follow these steps to ensure that the network is set up correctly:

1.	Open the Network Connections window. Right-click the Local Area Connection or Wireless Connection icon corresponding to your LAN connection and select Properties.
2.	Highlight Internet Protocol (TCP/IP) as shown in Figure 16.17, and click Properties. Figure 16.17. Highlight your LAN connection's Internet Protocol entry and click Properties to configure TCP/IP.
3.	Make the appropriate settings in the Properties page shown in Figure 16.18. If you are going to use Windows Internet Connection Sharing, first set up the one computer that will be sharing its connection, as described in Chapter 19, "Connecting Your LAN to the Internet." All of the computers, including the one sharing its Internet connection, should be set for automatic configuration as shown in Figure 16.18. If you are going to use a hardware router, configure the router first, following the manufacturer's instructions. Enable its DHCP feature. Set the starting DHCP IP address to 100, so that numbers from 2 to 99 can be used for computers with static settings. Also, if your ISP has provided you with static IP address settings, be sure to enter your ISP's DNS server addresses in the router's setup screens so it can pass them to the computers that rely on the router for their IP setup. (For more information about configuring a shared Internet connection, see Chapter 19.) Then, all of your computers should be set as shown in Figure 16.18. If you will not have a shared Internet connection, you should configure your network with static IP address information. Assign a unique number to each of your computers, starting with 2 and counting up. Open up the Internet Protocol Properties page as shown in Figure 16.18, and make the following settings: Use the following IP address select this item IP Address Enter 192.168.0.x, replacing x with the number you chose for this particular computer Subnet Mask Enter 255.255.255.0 Default Gateway leave blank Obtain DNS server address automatically select Figure 16.18. Internet Protocol (TCP/IP) Properties is the place to make IP address settings.

TIP

If your computer will move back and forth between networks that use automatic configuration and a network that uses static settings, say between work and home, make the static settings in the Alternate Configuration tab. This way, Windows will use the static settings only when a DHCP server is not present.

Using the Network Setup Wizard

Windows XP comes with a Network Setup Wizard program that you must run after installing your network. Its purpose is to configure your computer based on its relationship to other computers on your network and to the Internet.

Even if you want to manage all of the setup details yourself, on a Workgroup-type network you still have to run the Network Setup Wizard at least once; until you do, file and printer sharing is disabled. Then, after running the wizard, you can skip ahead to "Manually Configuring Your Network," later in this chapter.

NOTE

If you're going to use Microsoft's Internet Connection Sharing, configure the computer that will be sharing its Internet connection first. Establish and test its Internet connection, and only then configure the other computers. I'll describe this procedure in detail in Chapter 19. Otherwise, you can configure your computers in any order.

To start the wizard, click Start, Control Panel, Network and Internet Connections. From the task list, select Set Up or Change Your Home or Small Office Network. You can also start the wizard from the Network Connections page, using Set Up a Home or Small Office Network.

Read the "checklist for creating a network" if you wish, and then click Next again. Follow the wizard through the following steps.

Select a Connection Method

The wizard asks you to select a statement that best describes your computer's relationship to other computers on your network and to the Internet. The choices offered by the wizard are confusing, so I'm going to give a more detailed list of the different ways your computer might be set up. Identify the scenario in Table 16.2 that describes the particular computer you're setting up, and make the indicated selection in the wizard.

Table 16.2. Connection Scenarios for the Network Setup Wizard

Your Computer…	Make This Selection in the Wizard:
…will connect to the Internet via its own modem. You want to share this Internet connection with the rest of the network. …has two network adapters, one for the LAN, and a second one that that connects to a cable or DSL modem. You want to share this Internet connection with the rest of the network.	This computer connects directly to the Internet. The other computers on my network connect to the Internet through this computer.
…will connect to the Internet via its own modem. It is not to share its Internet connection with the rest of the network. …will be participating on the network for file and printer sharing only, and no computer on the network uses the Internet.	Other, Next, This computer belongs to a network that does not have an Internet connection.
…has no direct Internet connection of its own. It is to use a shared Internet connection that is made by a hardware Internet connection sharing router (wired or wireless), or by some other computer on the network that is set up to share its connection. …is on a corporate network. The Internet is available via the network, it has a firewall, and there are people who make sure our connection is safe. …will be using the network for file and printer sharing only, and won't use the Internet. However, other computers on the network do use the Internet.	This computer connects to the Internet through a residential gateway or through another computer on the network.
…has one network adapter. There is a cable modem connected directly to the network (to the same network hub), and you're paying for multiple computers to use the cable Internet service.	Other, Next, This computer connects to the Internet directly or through a network hub. Other computers on my network also connect to the Internet directly or through a hub.
…has two network adapters, one for a LAN, and a second one that connects to a cable or DSL modem (directly, or through a separate hub). This computer is not to share the Internet connection with the rest of the network. …uses a wireless Internet connection provided by a router or access point, and there is no WEP or WPA security key required for this connection.	You must take additional steps to secure your computer from hackers. See the following Caution for details.

CAUTION

If you have a network adapter that connects directly to the Internet via a cable or DSL modem, or through an unsecured Wireless connection, you'll choose This Computer Connects to the Internet Directly or Through a Network Hub… Windows will offer to turn off file and printer sharing and you should accept this offer. Windows will also turn on the Windows Firewall to offer some protection against hackers.

However, this is not enough, as some other people on the same Internet servicepeople you don't knowwill still be able to read and possibly change your shared files! You must ensure that File and Printer sharing the connection are disabled on the connection that goes to the Internet.

To disable File and Printer sharing, use the following procedure:

1.	Open the Network Connections window.
2.	Right-click the icon for the connection that goes directly to the Internet; this will be a Wireless Connection icon, or the Local Area Connection icon for the adapter that goes to the Cable/DSL modem. Select Properties.
3.	Uncheck Client for Microsoft Networks and File and Printer Sharing for Microsoft Networks. Then, click OK.
4.	If you have another wireless or Local Area Connection that goes to a separate LAN that you'll use for file and printer sharing, repeat this process for that connection, but this time ensure that Client for Microsoft Networks and File and Printer Sharing for Microsoft Networks are checked.

After making the appropriate connection selection, click Next and continue.

Select Your Internet Connection

If you indicated that you will be sharing your computer's Internet connection, or if there are two network adapters in your computer, Windows will ask you to select the one that is used to connect directly to the Internet. If you use a dial-up or PPPoE connection (a type of DSL service), choose the appropriate dial-up connection. Otherwise choose the network adapter that connects to your Internet service. Then, click Next.

Give This Computer a Description and a Name

Enter a brief description of the computer (such as its location or primary user) and a name for the computer. For the name, use just letters and/or numbers with no spaces or punctuation. Each computer on your LAN must have a different name.

If you're hard pressed to come up with a set of names, try the names of gemstones, composers, Impressionist painters, cartoon characters, or other interesting categories. I use the names of islands in the Indonesian archipelagowith more than 25,000 to choose from there's little chance of running out of unique names!

Some Internet service providers, especially cable providers, require you use a name that they'll provide. (If you have a hardware connection sharing device hooked up to your cable modem, the hardware device will use that name, and you can use any names you want on your LAN.)

Name Your Network

Choose a name for your network workgroup. The wizard will always try to get you to use the name MSHOME, but you can change it. This name is used to identify which computers should appear in your list of network choices later on. All computers on your LAN should have the same workgroup name, so if you don't use MSHOME, be careful to enter the selected name on every computer. If you have an existing network, be careful to enter the same workgroup name that the other computers are already using.

NOTE

The workgroup name must be different than all of the computer names.

Ready to Apply Network Settings

Review the list of selections you've made and either click Back to correct them or click Next to proceed.

You're Almost Finished

You'll need to run the wizard on the other computers on your LAN. If all the computers use Windows XP, select Just Finish the Wizard, and repeat the wizard process on the other computers. If you have computers running versions of Windows 95, 98, Me, NT, or 2000, you can create a diskette that will let you run the wizard on these older machines, or you can use your Windows XP CD-ROM in these computers.

To use a diskette, choose Create a Network Setup Disk, and insert a blank, formatted floppy disk. If you ran the wizard earlier and just changed some of the settings, choose Use the Network Setup Disk I Already Have, and re-insert the setup disk you created earlier.

Configure Other Computers

Repeat the wizard procedure on your other computers.

If a computer is running a version of Windows earlier than XP, you'll need the Network Setup Diskette you created earlier, or use the Windows XP CD-ROM. To fire up the wizard from a diskette, insert the diskette into the older computer. Click Start and Run, type a:setup, and press Enter.

To use the CD-ROM, insert the CD-ROM in the older computer and wait for it to auto-run the Windows setup program. Choose Perform Additional Tasks, and then Set Up Home or Small Office Networking.

Congratulationsyour network is set up! The next chapter will tell you how to start using your network.

Configuring Windows Firewall

After running the Network Setup Wizard, you must check that the Windows Firewall is set up correctly; otherwise you could end up exposed to Internet hacking, or could find that your network is so locked down that you can't use file and printer sharing. Windows Firewall is discussed in detail in Chapter 21, "Network Security."

If your Windows Professional computer is connected to a domain network, your network manager can and should configure your computer so that it uses a correctly configured Firewall "profile" when you are connected to the corporate network. You won't be able to change these settings. These administrators will also probably configure another "default" profile to protect you when you are disconnected from the corporate network, for example, when you are traveling or using your computer at home.

In this section I'll assume that you are managing your own computer, and that your network is not protected by a professionally installed firewall. Home and small office users should go through this quick checklist of steps to confirm that your network will function safely. The critical points are highlighted in boldface.

1.	Open the Windows Firewall window. You can get there from Start, Control Panel, Security Center, Windows Firewall.
2.	On the General tab, be sure that On is checked. Don't Allow Exceptions should normally be unchecked in order to use your LAN for file and printer sharing.
3.	On the Exceptions tab, be sure that the File and Printer Sharing entry is checked. Highlight this entry and click Edit. The dialog that appears should list the word Subnet four times, as shown in Figure 16.19. If any entry says Any rather than Subnet, you must change it: Highlight the entry, click Change Scope, and select My Subnet Only. Figure 16.19. The File and Printer Sharing service must be open to the local subnet only. Other entries present may also be checked, and they should also be set for "subnet" access only.
4.	On the Advanced tab, every connection name should have a check mark next to it. Check any that are missing.
5.	Click OK to close the Windows Firewall dialog and the Security Center window.
6.	If your computer connects to the Internet only via the LAN, that is, through a connection shared by a router or some other computer on your network, you can stop here. Otherwise, continue. If you computer connects directly to the Internet via a modem or a network adapter that connects to a broadband modem, Windows Firewall is not sufficient to protect you from hacking by other people who use your same Internet service provider! You must take the following steps to protect yourself:
7.	Open the Network Connections Window; if it's not on your Start menu, click Start, Control Panel, Network and Internet Connections, Network Connections.
8.	For each icon that represents a direct connection to the Internet (dial-up icons, or Local Area Connections that connect directly to a broadband modem), right-click the icon and select Properties.
9.	On the General tab, be sure that the only two items checked are Internet Protocol (TCP/IP) and QoS Packet Scheduler, as shown in Figure 16.20. Be sure that File and Printer Sharing and any "Client for" items are not checked. Check all of the connections that lead directly to the Internet itself. Figure 16.20. Connections that lead directly to the Internet must have only the Internet Protocol and QoS items checked.

This completes the procedure for setting up Windows networking on one Windows XP computer. Repeat the wizard procedure on your other computers, and you'll be able to start using your network.

If the other computers are running a version of Windows earlier than XP, you'll need the Network Setup Diskette you created earlier, or use the Windows XP CD-ROM. To fire up the wizard from a diskette, insert the diskette into the older computer. Click Start and Run, type a:setup and press Enter.

To use the CD-ROM, insert the CD-ROM in the older computer and wait for it to auto-run the Windows setup program. Choose Perform Additional Tasks, and then Set up home or small office networking.