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The Cable Modem Option

Cable companies have invested lots of capital (much more than telephone companies) to upgrade their networks in order to gain Internet market share. Their effort has paid off for you consumers, and many places in the United States now have access to high-speed Internet connections.

However, you have to consider some downsides:

Unfortunately, not all cable companies have caught up with 21st century technology. Many companies may provide you with TV service, but not with Internet service.

Many people don’t live in an area served by cable TV. Internet cable is also not a good medium to provide services such as Web page hosting.

Most cable companies require you to connect to their ISP. Many people like to use a different ISP because it provides better service. Using your own ISP also makes it easier to set up your computer (or network) to provide services going out to the Internet. Cable companies can’t prevent you from using a different local ISP, but they don’t charge you less — so you end up paying for two services, one of which you’re not using.

Few cable companies support Linux. You may get a connection, but you’re on your own if you need to troubleshoot problems, even problems that have nothing to do with Red Hat Linux but affect your machine.

If you decide that cable access is the right choice for your Internet access needs, here’s an overview of the process for connecting your Red Hat Linux computer to the Internet via a cable modem:

Do some research and subscribe to an ICP service.

Locate an Internet cable provider (ICP) — usually, your existing cable TV company — and subscribe to its ICP service.

Make a hardware commitment.

Obtain an Internet cable modem through your ICP. Many ICPs provide cable modems as part of their service. Otherwise, you can purchase the modem from the ICP or a consumer electronics store.

Get registered.

Register the cable modem with your ICP. You do have to register your modem with your ICP. During the registration process, your computer is assigned a network address to connect to the ICP. Network addresses are called Internet Protocol (IP) addresses.

You register your modem by giving your ICP the modem’s Media Access Control (MAC) address. The ICP generates an IP address by using the MAC address as its reference. You don’t need to do anything to your cable modem. The registration process is all done by your ICP, and your modem automatically is assigned an IP address. You’re ready to use your Internet cable modem to connect to the Internet. Woo-hoo! Blazing speed is yours now!

Set up the cable modem.

Cable modems have two connectors: a 75-ohm coaxial port and a twisted-pair (RJ-45) connector. (The coaxial connector is the same type that’s used for cable TV. The RJ-45 connector looks like a large telephone plug.)

Connect a coaxial cable from the cable modem’s coaxial port to the cable jack on your wall, just like you would a TV set.

Connect a network cable from the RJ-45 modem port to your Red Hat Linux computer. Normal network cables (referred to as Category 5 cables) don’t work if they’re connected directly from the modem to your computer. You need to use a crossover cable if you want to directly connect a computer to a cable modem. You can use normal Category 5 cables if you connect the cable modem and your computer to an Ethernet hub or switch.

Set up your Internet protocols.

Configure your computer to use DHCP on the network interface that connects to the modem. Restart your computer’s network interface, and you should be good to go.

The following sections take you through the process of finding a cable provider and setting up your access.

Finding an Internet cable provider

Finding an Internet cable provider (ICP) is as simple as calling your cable television company. Not all cable TV systems carry Internet traffic, but many do.

RememberLocating a cable television company that provides broadband Internet connections is unfortunately quite easy. It’s unfortunate because little competition exists within the cable industry. Federal law effectively restricts competition within municipalities and creates the environment for monopoly-like companies. The result, of course, is that prices remain higher than necessary. Oh, well, at least many cable companies are offering Internet connections.

Your ICP is your default Internet Service Provider (ISP). Most cable companies give you one or more e-mail addresses. However, cable companies don’t generally provide login accounts, like other ISPs do.

Login accounts are used for launching applications and storing information. They aren’t essential, but they’re useful. However, nothing stops you from maintaining a regular ISP and using its login account. You then have a high-speed Internet connection you can use to log in to any account you have.

TipWe don’t run you through the process of signing up for cable Internet service; we think that the process is simple enough. A good portion of the sign-up process involves waiting on hold and listening to Muzak. One suggestion, though: Make sure that you have pertinent information about your system and that the cable company knows you’re using Red Hat Linux 10.

Dealing with the hardware

One great thing about Internet cable is that you can buy the cable modems from your local electronics store or an Internet distributor. DSL equipment is less readily available. Cable modems are generally priced the same whether you purchase through your provider, the Internet, or a bricks-and-mortar store. (Cable companies sometimes run promotions where they return by rebate most, if not all, of the price of the modem.) But the convenience of running to a local store is great, especially if your cable modem breaks on a Saturday night and you just have to download the latest game patch.

RememberBefore you purchase a cable modem, make sure that you

Ask whether you have to buy your modem through the cable provider. If not, you can shop around for the best price.

Make sure that the modem you buy is compatible with your service provider. The cable industry is converging on using the Data Over Cable Service Interface Specification (DOCSIS) as its Internet hookup standard. DOCSIS modems are quite easy to configure, so keep your fingers crossed that your service provider uses them.

If your provider doesn’t use DOCSIS, you likely have to purchase your modem through your provider.

Modern cable modems do more than just transmit network packets. They transmit data packets by modulating and demodulating electrical signals over the cable TV wires — thus, the name modem (modulate/demodulate). Cable modems now use the industry standard Data Over Cable Service Interface Specification (DOCSIS) protocol to deliver electrical signals across the cable network. The electrical signal carries the actual bits and bytes that comprise the network packets. A good analogy is an AM-FM radio system. The DOCSIS–based electrical signals carry data packets just like radio waves transmit speech or music.

The instructions we provide later in this chapter are designed for DOCSIS modems.

Setting up your cable modem is usually a straightforward process. Modern DOCSIS cable modems act as network bridges. A network bridge simply rebroadcasts network packets in both directions — incoming and outgoing. One side of the bridge connects to the cable TV company. The other side connects to your computer through your Ethernet NIC through a Category 5 crossover cable; you can also connect through a network switch or hub (LAN). If your modem is the bridge type — we believe that the cable industry in the United States mostly uses that system — it doesn’t require any configuration.

Setting up Internet protocols

You don’t have to configure your cable modem for it to work. What you do need to do, however, is tell your Red Hat Linux computer how to connect to the modem. Cable modems typically connect to your computer via an Ethernet network interface. Therefore, you need to connect the cable modem to your computer using an Ethernet-based network.

You need to configure your Red Hat Linux computer’s Ethernet adapter using the Dynamic Host Configuration Protocol (DHCP); you need an Ethernet adapter, of course, installed on your computer. Your cable modem sets the IP address of your Ethernet NIC by using DHCP. These instructions show how to do that:

Log in to your computer.

Click the GNOME Menu button (the button in the lower-left corner of your screen that looks like a red fedora) and choose System SettingsNetwork.

The Network menu pops up, prompting you to enter the root password if you’re not logged in as the root user.

Enter the root password if prompted, click OK, and create an Ethernet connection by clicking the New button.

The Select Device Type window opens.

Select the Ethernet connection option and click the Forward button.

The Select Ethernet Device window opens, showing the Ethernet device (or devices) that the Network utility found.

Click the Forward button.

The Configure Network Settings window opens, as shown in Figure 6-1. By default, the Automatically Obtain IP Address settings with DHCP option is selected; the Automatically Obtain DNS Information from Provider button is activated too. These are the settings you need to use with DOCIS cable modems. However, you can select a name for your computer.

Pick a name for your computer and enter it in the Hostname (Optional) text box.

This step is optional, so you can skip it and go to Step 7, if you want.

Click the Forward button.

The Create Ethernet Device window opens, showing a summary of your Ethernet interface’s configuration.

Click the Apply button and control returns to the original Network Configuration window.

The Network Configuration window shows your new Ethernet device. However, you still need to save your changes before exiting the configuration system.

Choose FileSave and click the OK button.

Before you click OK, an Information window pops up, telling you that your changes have been saved and that you need to restart your network or computer to make them take effect.

Control returns to the Network Configuration window.

Click the Activate button and your new Ethernet NIC turns on.

Choose FileQuit to close the Network Configuration window.

You have created and saved the configuration necessary to use your cable modem. You have also activated that connection. You can start using your broadband Internet connection. Open Mozilla, for example, and start browsing at lightning speed.

Figure 6-1: The Configure Network Settings window.

RememberWe strongly advise against leaving your Internet connection permanently active until you protect yourself with a firewall. Turn off your Internet connection — turn off the modem, for example. If you’re not using the default firewall that comes with Red Hat Linux, of if you’re looking for a more secure firewall, go to Chapter 8. After the firewall is working, you can restart your Internet connection and be reasonably safe from hackers.