Suse Linux 9.3 For Dummies- P10 ppsx

To Internet backbone A neighborhood one or more homes with cable modems Another neighborhood all homes with cable modems share same cable Cable Modem Termination System CMTS Cable compan

The coaxial cable that carries all those hundreds of cable TV channels to your home is a very capable signal carrier In particular, the coaxial cable can carry signals covering a huge range of frequencies — hundreds of megahertz (MHz) Each TV channel requires 6 MHz — and the coaxial cable can carry hundreds of such channels The cable modem places the upstream data in a small frequency band and expects to receive the downstream data in a whole other frequency band

To Internet backbone

A neighborhood (one or more homes with cable modems)

Another neighborhood (all homes with cable modems share same cable)

Cable Modem Termination System (CMTS)

Cable company head end (the central distribution point)

Your PC Cable Modem

1

Ethernet card in PC From

cable TV

1 1

0 0 0

Figure 7-4:

Cable modems provide high-speed Internet access over the cable TV network

At the other end of your cable connection to the Internet is the Cable Modem Termination System (CMTS) — also known as the head end — that your cable

company installs at its central facility (Refer to Figure 7-4.) The CMTS con-nects the cable TV network to the Internet It also extracts the upstream digi-tal data sent by your cable modem (and by those of your neighbors as well) and sends all of it to the Internet The CMTS also puts digital data into the upstream channels so that your cable modem can extract that data and pro-vide it to your PC via the Ethernet card

Cable modems can receive downstream data at the rate of about 30 Mbps and send data upstream at around 3 Mbps However, all the cable modems

in a neighborhood share the same downstream capacity Each cable modem filters out — separates — the data it needs from the stream of data that the CMTS sends out Cable modems follow a modem standard called DOCSIS, which stands for Data Over Cable Service Interface Specification You can buy any DOCSIS-compliant modem and use it with your cable Internet service; all you have to do is call the cable company and give them the modem’s identify-ing information so that the CMTS can recognize and initialize the modem

In practice, with a cable modem you can get downstream transfer rates of around 1.5 Mbps and upstream rates of 128 Kbps These are maximum rates, and your transfer rate is typically lower, depending on how many users in your neighborhood are using cable modems at the same time

If you want to check your downstream transfer speed, go to bandwidth place.com/speedtestand click the link to start the test For my cable modem connection (for example), the tests reported a downstream transfer rate of about 1.4 Mbps

Typical cable modem setup

To set up cable modem access, your cable TV provider must offer high-speed Internet access If the service is available, you can call to sign up The cable companies often have promotional offers such as no installation fee

or a reduced rate for three months Look for these offers If you are lucky, a local cable company may have a promotion going on just when you want to sign up

The installation is typically done by a technician, who splits your incoming cable into two — one side goes to the TV and the other to the cable modem The technician provides information about the cable modem to the cable company’s head end for setup at its end When all that is done, you can plug

in your PC’s Ethernet card to the cable modem and you’re all set to enjoy high-speed Internet access Figure 7-5 shows a typical cable-modem hookup

The cable modem connects to an Ethernet card in your PC If you don’t have an Ethernet card in your PC, the cable company technician often provides one

Here are some key points to note about the cable modem setup in Figure 7-5:

 Split the incoming cable TV signal into two parts by using a two-way splitter (The cable company technician installs the splitter.) By the way, the two-way splitter needs to be rated for 1 GHz; otherwise, it may not let the frequencies that contain the downstream data from the Internet pass through

 Connect one of the video outputs from the splitter to your cable modem’s F-type video connector using a coaxial cable

 Connect the cable modem’s 10BaseT Ethernet connection to the Ethernet card on your PC

 Connect your TV to the other video output from the two-way splitter

Ethernet card

in your PC

10BaseT Ethernet cable

To cable distribution box

Two-way splitter

Television set

Your PC

Cable Modem

lc le Coaxial cables

Figure 7-5:

The cable

TV signal

is split between the TV and the cable modem

When you use a cable modem to directly connect your SUSE Linux PC to the Internet, the connection is always on, so you run a greater risk that someone may try to break into the PC than do dialup users SUSE Linux includes a fire-wall, which you may want to use to protect your PC from unwanted Internet connections See Chapter 19 for more information on how to enable the firewall

To isolate your SUSE Linux PC or local area network from the public Internet, you may want to add a NAT (Network Address Translation) router between your PC and the cable modem One of the NAT router’s network interfaces con-nects to the Internet and the other concon-nects to your LAN — the router then acts as a gateway between your LAN and the Internet As an added bonus, you can even share a cable modem connection with all the PCs in your own local area network (LAN) by adding an Ethernet hub Better yet, buy a combination NAT-router-and-hub so you have only one box do the whole job By the way,

the NAT router/hubs are typically sold under the name Cable/DSL router

because they work with both DSL and a cable modem

The NAT router translates private Internet Protocol (IP) addresses into a public IP address When connected through a NAT router, any PC in the inter-nal LAN can access the Internet as if it had its own unique IP address Result: You can share a single Internet connection among many PCs (An ideal solu-tion for an entire family of Net surfers!)

Figure 7-6 shows a typical setup with a cable modem connection being shared by a number of PCs in a LAN

Here are the points to note when setting up a connection like the one shown

in Figure 7-6:

 You need a Cable/DSL NAT router with two 10BaseT Ethernet ports (the 10BaseT port — also known as an RJ-45 jack — looks like a large phone

jack) Typically, one Ethernet port is labeled Internet (or External or WAN for wide area network) and the other one is labeled Local.

 If you plan to set up a LAN, you also need an Ethernet hub For a small home network, you can buy a 4- or 8-port Ethernet hub Basically, you want a hub with as many ports as the number of PCs you intend to con-nect to your local area network

 Consider buying a single box that acts as both a NAT router and a hub with a number of Ethernet ports

 Connect the video cable to the video input port of the cable modem

 Connect the Ethernet port of the cable modem to the Internet port of the NAT router using a 10BaseT Ethernet cable (These look like phone wires, except that the Ethernet cables have bigger RJ-45 jacks and are often labeled Category 5 or Cat 5 wire.)

 Connect the Local Ethernet port of the NAT router to one of the ports on the Ethernet hub using a 10BaseT Ethernet cable

 Now connect each of the PCs to the Ethernet hub Of course, each PC must have an Ethernet card

In the next section, I explain how to configure the PCs in such a LAN so that they can all access the Internet through the router

Dialing Up the Internet

If you don’t have DSL or a cable modem, you can always reach the Internet the old-fashioned way — you can just dial up your ISP using your PC’s modem (you need a modem and a phone line for this to work) Connecting

your PC to the Internet through a dialup modem is called dialup networking.

In the following sections, I show you how to set up a dialup network connec-tion to your ISP

Ethernet cables (10BaseT)

Ethernet hub

NAT router Ethernet cables (10BaseT)

PCs in a local area network (LAN)

Each PC must have a 10BaseT Ethernet card

To cable distribution box

Two-way splitter

Cable modem Video cable

To television

Figure 7-6:

A NAT router isolates your PC from the Internet and also lets you share a cable modem connection with other PCs in a local area network

To use a modem to dial up and connect to the Internet, you have to first get

an account with an ISP Every ISP provides you a phone number to dial, a username, and a password Additionally, the ISP gives you the full names of servers for e-mail and news Typically, your system automatically gets an IP address by using a protocol known as DHCP

Connecting the modem

Modem is a contraction of modulator/demodulator — a device that converts

digital signals (string of 1s and 0s) into continuously varying analog signals that transmit over telephone lines and radio waves Thus, the modem is the intermediary between the digital world of the PC and the analog world of tele-phones Figure 7-7 illustrates the concept of a modem

Inside the PC, 1s and 0s are represented with voltage levels, but signals car-ried over telephone lines are usually tones of different frequencies The modem sits between the PC and the telephone lines and makes data commu-nication possible over the phone lines The modem converts information back and forth between the voltage/no voltage representation of digital cir-cuits and different frequency tones that are appropriate for transmission over phone lines

Before you dial out using an external modem, make sure that the modem is powered on and properly connected to one of the serial or USB ports of your

PC You must also connect the modem to the telephone line

Buy the right type of cable to connect the modem to the PC You need a straight-through serial cable to connect the modem to the PC The connec-tors at the ends of the cable depend on the type of serial connector on your

PC The modem end of the cable needs a male 25-pin connector The PC end

Modem

1 1 1

0 0 0

Figure 7-7:

A modem bridges the digital world

of PCs and the analog world of telephones

of the cable often is a female 9-pin connector You can buy modem cables at most computer stores Often, you can find 9-pin-female-to-25-pin-male modem

cables sold under the label AT Modem Cable Connect USB modems by using

a USB cable

If your PC has an internal modem, all you have to do is connect the phone line to the phone jack at the back of the internal modem card

Whether your PC has an internal modem or you connect an external modem, you have to configure the modem

Configuring the modem

To configure the modem for dialup networking, follow these steps:

1 Choose Main Menu➪System➪YaST in KDE or System Menu➪YaST in GNOME.

The YaST Control Center runs and its main window appears

2 Click Network Devices on the left pane of the YaST Control Center and then click Modem on the right pane.

YaST opens the Modem Configuration window and displays information about the modem it detects (see Figure 7-8)

Figure 7-8:

Configure the modem from YaST

3 Click the Configure button and enter any requested information (click Next to move from one screen to the next).

On the ISP screen, click New and then type the ISP’s phone number as well as the username and password of your Internet account with the ISP (You can guess where to enter these items; just look for the fields labeled Username, Password, and Phone Number.) Aside from these fields, you can accept the default settings from the rest of the configura-tion screens

After you finish configuring the modem, the KInternet tool starts and displays a small window with a plug icon, as shown in Figure 7-9

4 Click the KInternet tool’s plug icon to activate the dialup connection.

If the connection does not seem to come up, right-click the KInternet icon, select View Log, and look for clues about any problems

Figure 7-9:

Click the KInternet tool to activate a dialup connection

Chapter 8

Setting Up an Ethernet LAN with Wireless Access

In This Chapter

Setting up an Ethernet LAN

Connecting your LAN to the Internet

Extending your network’s reach with wireless

Checking whether your network is up and running

You might use an Ethernet network for your local area network (LAN) —

at your office or even your home (if you happen to have several systems

at home) Even if you have a single PC, you may need to set up an Ethernet network interface so that you can connect your PC to high-speed Internet access that uses a DSL or cable modem (I cover DSL and cable modems in Chapter 7.) In this chapter, I explain how to set up an Ethernet network

If you want to surf the net from anywhere in your home with your laptop

PC, you can do so by adding wireless to your network In the last part of this chapter, I show you how to set up wireless networking for connecting

to an Ethernet LAN and accessing the Internet

Getting a Handle on Ethernet

Ethernet is a standard way to move packets of data between two or more

computers connected to a single hub (You can create larger networks by connecting multiple Ethernet segments with gateways.) To set up an Ethernet local area network (LAN), you need an Ethernet card for each PC Linux sup-ports a wide variety of Ethernet cards for the PC

Ethernet is a good choice for the physical data-transport mechanism for the following reasons:

 Ethernet is a proven technology that has been in use since the early 1980s

 Ethernet provides good data-transfer rates: Typically 10 million bits per second (10 Mbps), although 100-Mbps Ethernet and Gigabit Ethernet (1,000 Mbps) are now available

 Ethernet hardware is often built into the PC or can be installed at a relatively low cost (PC Ethernet cards cost about $10 to $20 U.S.)

 With wireless Ethernet, you can easily connect laptop PCs to your Ethernet LAN — without having to run wires all over the place I explain wireless Ethernet later in this chapter

Connecting PCs to an Ethernet LAN

Any time you hear experts talking about Ethernet, you’re also going to hear some bewildering terms used for the cables that carry the data Here’s a quick rundown

Nowadays, the most popular form of Ethernet cabling is unshielded twisted-pair cable (UTP), known as 10BaseT or 100BaseT (because it can support data rates up to 100 megabits per second) The Electronic Industries Association/ Telecommunications Industries Association (EIA/TIA) defines the following five categories of shielded and unshielded twisted-pair cables:

 Category 1 (Cat 1): Traditional telephone cable

 Category 2 (Cat 2): Cable certified for data transmissions up to 4 Mbps

 Category 3 (Cat 3): Cable that can carry signals up to a frequency of

16 MHz Cat 3 is the most common type of wiring in old corporate net-works and it normally contains four pairs of wire

 Category 4 (Cat 4): Cable that can carry signals up to a frequency of

20 MHz Cat 4 wires are not that common

 Category 5 (Cat 5): Cable that can carry signals up to a frequency of

100 MHz Cat 5 cables normally have four pairs of copper wire Cat 5 UTP is the most popular cable used in new installations today

To set up a 10BaseT Ethernet network, you need an Ethernet hub — a hard-ware box with RJ-45 jacks (These look like big telephone jacks.) You build the network by running twisted-pair wires (usually, Category 5, or Cat5, cables) from each PC’s Ethernet card to this hub You can get a 4-port 10BaseT hub for about $20 U.S Figure 8-1 shows a typical small 10BaseT or 100BaseT Ethernet