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Configuring Your NIC with the Red Hat Network Utility

To use your Red Hat Linux computer with an existing Local Area Network (LAN), you need a wireless or Ethernet NIC installed on your computer and a network hub, or switch, to which to connect the NIC. After you set up the hardware, you need to configure your Red Hat Linux network settings.

Remember If your LAN also has an Internet connection, you can set up that connection too. Although a high-speed Internet connection is best, in terms of the network configuration the type of connection doesn’t matter.

Technical Stuff IEEE and wireless networks

The dominant wireless standard is based on the IEEE 802-11b (and the older 802-11a and the about-to-be-released 802-11g) standard; 802-11b is also referred to as Wi-Fi (which is short for the wireless industry’s trade term wireless fidelity). If you hear people talking about a Wi-Fi NIC, they’re just talking about wireless NICs.

IEEE (pronounced “eye-triple-e”), or Institute of Electrical and Electronic Engineers, is a worldwide professional society of nerds. (Is it necessary to use words like nerds or geeks to convey some technical meaning?) The IEEE, the “triclops” of wireless networking, concerns itself with issues such as which frequency wireless networking devices should use. Fortunately, this group has devised this wonderful standard that now enables everyone who’s interested to communicate without stringing wires between machines.

Preparing to configure your wireless NIC

Before you can configure your wireless NIC, you need to figure out two things:

Which type of wireless NIC you have (or need)

How your wireless NIC should connect to your network

Two main types of wireless electronics (or chip sets) are now in use: Wavelan, built by Lucent Technologies, and Prism2, designed by Intersil. Both types are supported by Red Hat. The following list shows the manufacturers of each type. You can use the list to help figure out what kind of chip set your device uses:

Wavelan: Orinoco, Apple Airport Enterasys RoamAbout 802, Elsa AirLancer 11, and Melco/Buffalo 802.11b.

Prism2: D-Link DWL-650, LinkSys, Netgear, WPC11, and Compaq WL110. Other, less popular models include Addtron AWP-100, Bromax Freeport, GemTek WL-211, Intalk/Nokia, SMC 2632W, YDI, Z-COM X1300, and Zoom Telephonics ZoomAir 4100.

You need to figure out how your wireless NIC (or network adapter) should connect to your network. Wireless NICs can connect to a LAN in two ways:

Adapter-to-adapter: This type, referred to as an ad hoc connection, is useful if you have two or more computers that you want to talk and form their own, exclusive private network.

Adapter-to-wireless hub: This type, called infrastructure, provides a single entrance (an access point) into a LAN. An access point allows one or more computers to be connected to a network. However, unlike an ad hoc network, the individual computers can connect to any access point that allows them to.

The wireless-configuration instructions we provide work with either the infrastructure or ad hoc connection methods. Your wireless NIC can connect to either the access point or other computers (Linux and Windows) as long as you correctly configure your Network ID (ESSID) and encryption key.

Choosing between ad hoc and infrastructure

Using ad-hoc mode provides three advantages:

Lower costs: You don’t have to purchase an access point; an access point starts at around $50. Computers using wireless NICs running in ad-hoc mode communicate directly with each other, eliminating the need for a common access point.

Simpler configuration for Linux users: Older access point devices could be configured using only Windows-based software — the simple network management protocol (SNMP), to be exact. You had to physically connect a Windows computer to the access point via a wired Ethernet network and then use the software supplied with the device. That was difficult if you didn’t have any Windows-based computers. Newer access points tend to use HTML-based configuration systems, so you can use Mozilla to configure these newer devices.

No need to configure any access point: You need to configure only the wireless NIC in each computer on your network. You can use the Red Hat Network Configuration Utility to configure a wireless NIC, which simplifies the process. Each NIC must have the same Network ID and encryption key.

Ad hoc networks can also provide a bit more security because they connect to other networks — and the Internet — through a network router. Access points work as network bridges. Routers examine IP addresses and then decide where to direct network traffic from one network to another. Bridges automatically pass on all traffic. Ad hoc networks can be configured to more tightly — but not completely — control network traffic than access-point-based networks. You can configure ad hoc networks with a firewall more easily than a network using an access point. (Many of the current crop of access points now provide NAT and firewall support, however; using NAT effectively creates a firewall.)

Wireless network warning

Wi-Fi, the standard for wireless technology, uses an encryption system named wireless equivalent privacy (WEP) to provide security. WEP encrypts communication between wireless devices to prevent someone with the right equipment from listening to and using your wireless network. But WEP is flawed and can be broken using tools available on the Internet (that’s a big surprise). If a hacker breaks in to your Wi-Fi network, he can read your communications. But your problems don’t end there. Hackers can use your wireless network to connect to both your private network and the Internet; you give the bad guys a free lunch and a launch pad to the Internet.

On the other hand, wireless networking is so useful that many people make accommodations for the risk. The logic? If you assume that your wireless network has already been hacked, you don’t have to worry about when it might be hacked in the future.

You should use OpenSSH, Secure Sockets Layer (SSL), and virtual private networks (VPN) — all bundled with Red Hat Linux — to conduct all your internal and external communication. Keep in mind that using SSH, SSL, and VPN protects your information, but doesn’t prevent someone from connecting to your network. The next generation of Wi-Fi, 802.11g, is supposed to fix the WEP weakness. Until the WEP problems are solved, be aware of the risks.

Configuring your Ethernet or wireless NIC

To get your Red Hat Linux computer working on a LAN, you must first configure its network interface card, or NIC. The NIC is the device that electronically connects your computer to your LAN. To work with the other computers on your network, your Ethernet or wireless adapter must be given a network address and a few other pieces of information.

TipWe have divided the configuration instructions between Ethernet and wireless (or Wi-Fi) NICs. The instructions start by explaining how to start the Red Hat Network Configuration Utility. We then devote a subsection apiece to describing the particulars of configuring Ethernet and wireless devices. After we cover the device specifics, we discuss general configuration issues. The overall configuration process is outlined in these steps:

Start the Network Configuration Utility.

Configure your Ethernet or wireless device.

Configure your computer’s host name.

Configure your computer’s domain name service.

Restart your network.

Starting the Network Configuration Utility

Follow these steps to start the Network Configuration Utility:

Click the GNOME Main Menu button and choose System SettingsNetwork.

Tip Alternatively, you can click the GNOME Menu button and choose System ToolsNetwork Device Control. When the Network Device Control window opens, select the Ethernet or wireless device and click the Configure button. The Network Configuration Utility starts.

Enter the root password if you’re prompted to do so.

Figure 7-1 shows the initial configuration window. A NIC may or may not be displayed in the window. The NIC is displayed only if you configured your networking during the Red Hat installation.

Figure 7-1: The Devices tab in the Network Configuration window.

Click the New button if no NIC is displayed on the Devices tab or if you want to configure an additional one.

Otherwise, skip to Step 3 in the following section when you’re working with an Ethernet device; skip to Step 1 in the section “Configuring a wireless NIC,” later in this chapter, if you’re working with a Wi-Fi NIC.

The Select Device Type window appears.

Select the appropriate type from the list of devices and then click the Forward button.

For example, select Ethernet if you’re using that type of interface. If you’re using a Wi-Fi (also referred to as wireless or IEEE 802.11b) device, select Wireless Connection.

What you do next depends on whether you’re configuring an Ethernet or a wireless NIC. The following two sections are devoted to Ethernet and wireless NICs, respectively.

Configuring an Ethernet NIC

If you’re using an Ethernet NIC, follow the steps in this section to configure its parameters (if you’re using a wireless NIC, go to the following section):

Follow the steps in the section “Starting the Network Configuration Utility,” earlier in this chapter.

When you choose Ethernet from the drop-down list in Step 4 on the preceding list, the Select Ethernet Device window appears.

Select the appropriate Ethernet device and click the Forward button.

The Network Configuration utility detects all Ethernet devices attached to your computer. Most PCs have only one Ethernet device, so you don’t have to make a decision about which one to select.

The Configure Network Settings window opens as shown later in this section, in Figure 7-2.

Figure 7-2: Entering your static (non-DHCP) IP address settings.

Configure your TCP/IP address settings.

The Red Hat Network Configuration Utility selects DHCP (Dynamic Host Configuration Protocol) as the default method for determining your machine’s IP address. (DHCP dynamically assigns an IP address and other parameters to your Ethernet NIC, and you’re finished configuring your NIC.) If you’re connecting to a network that provides DHCP service, type your computer name in the Hostname (optional) field (for example, Cancun), click the Forward button, and go to Step 9.

If your network doesn’t use DHCP, you need to manually configure your IP address. Proceed to Step 4.

Click the Statically Set IP Addresses radio button.

You should ask your friendly local system administrator (unless you’re the administrator, in which case you may want to avoid talking to yourself) which system your network uses.

Tip Life is a bit more complicated if you have both a wireless and an Ethernet NIC on your computer. You can run both devices at one time, but the configuration is more difficult. You can solve the problem by clicking the Automatically Obtain IP Address Settings With radio button so that the dot disappears. This simple mouse click prevents the Ethernet NIC from starting automatically.

Assign an IP address to your computer by typing it in the Address text box.

Technical Stuff IP addresses are analogous to street addresses: They provide a number that uniquely distinguishes your machine from all others. Private IP addresses don’t require any registration with the powers that be — the InterNIC organization that distributes IP addresses. Public IP addresses aren’t routed on the Internet and can be used on LANs for your own use.

If you’re on a network with registered IP addresses, be sure to get an IP address from your system administrator. Otherwise, go ahead and use a private IP address. (Use any Class C address between 192.168.1.1 and 192.168.254.254; for example, 192.168.1.20 or 192.168.32.5.) Private IP addresses in this range are designated for use by private networks. By design, private IP addresses don’t get routed (sent from one machine to another) through the Internet, and anyone can use them. Private IP addresses would wreak havoc on the Internet if they were routed.

Type 255.255.255.0 or the netmask for your IP address in the Subnet Mask text box.

Technical Stuff The Internet Protocol (IP) defines only three network address classes: A, B, and C. Only Class C addresses are assigned by InterNIC. Use the 255.255.255.0 netmask for Class C networks, 255.255.0.0 for Class B, and 255.0.0.0 for Class A.

Remember Class C netmasks are used almost universally now, and we use only Class C addresses here. If you’re not using a Class C address, you’re probably experienced in the ways of TCP/IP and know which netmask to use. Godspeed. Otherwise, don’t fool with Mother Nature: Use a Class C address.

In the Default Gateway Address text box, type the IP address of the Internet gateway for your LAN.

The Internet gateway is the device (router or computer) that connects your network to your ISP and the Internet. Obtain the address from your system administrator if you’re at work and have one. If you’re a home user, a typical convention is to assign the highest address — 254 — of a Class C subnetwork as the gateway. For example, type 192.168.1.254.

Your TCP/IP Settings should look similar to the dialog box shown in Figure 7-2.

Click the Forward button.

The Create Ethernet Device dialog box opens, indicating that you have finished the configuration process. The dialog box shows a summary of the information you entered in the preceding steps.

Review the summary and click the Apply button.

You return to the Network Configuration window that now displays the newly configured Ethernet NIC.

Save the new configuration by choosing FileSave.

A dialog box opens, informing you that your changes have been saved. Click the OK button to continue.

Start the NIC by clicking the Activate button.

This step completes your Ethernet NIC configuration.

Your Ethernet NIC is now active. But you still need to configure your domain name service (DNS) if you aren’t using DHCP. Proceed to the section “Configuring DNS service,” a little later in this chapter.

Technical StuffKernel modules are the Linux equivalent to Microsoft Windows device drivers. Usually, Red Hat Linux can detect your Ethernet adapter and automatically load the correct module. However, if Red Hat Linux can’t find your Ethernet adapter, you probably can’t find the correct one on the supplied list. You can still go ahead and try; there’s no harm in that.

Configuring a wireless NIC

This section describes how to configure the parameters for a wireless NIC, also called a Wi-Fi NIC. (Skip this section if you don’t have a wireless NIC.)

The following steps describe how to configure your wireless device:

Follow the steps in the section “Starting the Network Configuration Utility,” earlier in this chapter.

When you choose Wireless from the drop-down list in Step 4 on the earlier list, the Select Wireless Device window appears.

Select the appropriate wireless device.

Click the Forward button.

The Configure Wireless Connection window opens, as shown in Figure 7-3.

Figure 7-3: The Configure Wireless Connection dialog box.

Select either Managed or Ad-Hoc from the Mode drop-down list.

You use Managed mode when you’re using an access point. Use ad-hoc mode if you configured a wireless network without an access point.

Type ANY in the ESSID (Network ID) text box if you use an access point. Type the specific ESSID name for an ad hoc network.

All machines connected to an ad hoc wireless network must share the same ESSID. For example, you may choose the string mynetwork as your ESSID. In that case, you must enter mynetwork as the ESSID for all machines connected to your ad hoc network.

Enter the encryption key in the Key text box and then click the Forward button.

You should obtain the encryption key from your network administrator. If you have set up your own wireless home network, you can generate the key yourself. An encryption key, similar to a password, protects your wireless network from casual eavesdropping. Enter in the text box a key that’s 13 characters or fewer — for example, this_is_a_password; using all 13 characters maximizes the encryption key’s effectiveness.

TipEncryption keys are 40- or 128-bit binary numbers. They can be represented as text strings, as described in Step 6, or as a string of hexadecimal — hex — numbers. Hex numbers are commonly used in computer science to represent binary numbers. For your purposes, it’s sufficient to know that a hex number is represented by 16 characters: 0 through 9 and A through F. For example, hex 0 is represented as decimal 0; hex 3, as decimal 3; and hex 9, as decimal 9. But decimal 10 is hex A, and the decimal 16 hexadecimal value is F. The hexadecimal value of this sample key:

-- this_is_a_password --

is

746869735F69735F615F6B6579

You can enter the hex value in the Key field by prepending the string 0x to the key. In the example, you enter this line:

0x746869735F69735F615F6B6579

After you enter your encryption key and click the Forward button, the Configure Network Settings window opens. The processes of assigning a host name, IP address, netmask, and gateway to your computer are the same as for an Ethernet interface. Consult Steps 3 through 9 in the preceding section for instructions on how to configure your wireless NIC TCP/IP parameters.

Your wireless NIC configuration is complete. You still need to configure your domain name service (DNS) if you aren’t using DHCP. Proceed to the following section if that’s the case.

Configuring DNS service

You need to configure your computer to use from one to three DNS servers. You can use your LAN’s DNS servers, if they’re available. You can also use external DNS servers whether or not any exist on your LAN. To configure your Red Hat Linux computer to use DNS, follow these steps:

Click the DNS tab in the Network Configuration dialog box, which is where you leave off in the preceding list of steps.

Type the host name of your computer in the Hostname text box.

The host name is any name (for example, Cancun) that you want to use.

If you’re connecting to a network controlled by someone else (for example, at work), check with the system administrator before selecting a host name.

Type the IP address of your DNS server in the Primary DNS text box.

If your LAN provides a DNS server, you can use it as your primary name server (DNS).

If you have one, type the IP address of your secondary name server in the Secondary DNS text box.

Most ISPs provide a backup DNS server address. If your LAN has its own DNS server, you can specify your ISP server as your secondary DNS server, if you want.

Type the domain name of your network in the DNS Search Path text box.

Figure 7-4 shows a sample DNS configuration screen.

Figure 7-4: A sample NDS configuration.

A domain name is a 2-part name separated by a period. For example, paunchy.net is a domain name, which is the domain name of the sample LAN used in this book. You should replace the paunchy.net domain name, of course, with the name of your LAN.

Choose FileQuit.

The Network Configuration Utility closes. Your settings are saved and are activated the next time you reboot your computer. Proceed to the following section to activate your settings immediately.