Deciding How to Connect to the Internet

Nowadays, you have the following popular options for connecting a small office or home office to the Internet (of course, huge corporations and governments have many other ways to connect to the Internet):

Digital subscriber line (DSL)-Your local telephone company as well as other telecommunications companies offer DSL-a high-speed data transmission service over a regular phone line. You can use DSL to connect your Red Hat Linux system to the Internet. In this case, you must connect a special DSL modem to an Ethernet card on your Red Hat Linux system. When you use DSL, your Red Hat Linux system is always connected to the Internet. Typically, DSL offers data transfer rates of anywhere between 128 Kbps and 1.5 Mbps. You can download from the Internet at much higher rates than when you send data from your PC to the Internet (upload). One caveat with DSL is that your home must be between 12,000 and 15,000 feet from your central office (this is a phone company facility where your phone lines end up). The distance limitation varies from provider to provider. In the United States, you can check out the distance limits for many providers at www.dslreports.com/distance.
Cable modem-If the cable television company in your area offers Internet access over cable, you can use that service to hook up your Red Hat Linux system to the Internet. As with DSL, connect a cable modem to an Ethernet card in your Red Hat Linux system. Typically, cable modems offer higher data transfer rates than DSL for the same cost. Downloading data from the Internet is much faster than sending data from your PC to the Internet. You can expect routine download speeds of 1.5 Mbps and upload speeds of around 128 Kbps, but sometimes you may even get higher speeds than these.
Dial-up networking-This is what most of us were using to connect to the Internet before DSL and cable modems came along. In this case, your Red Hat Linux system uses the Point-to-Point Protocol (PPP) or Serial Line Internet Protocol (SLIP) over a dial-up link to connect to another system already on the Internet. Usually, that Internet-connected system belongs to your Internet service provider (ISP). This method of connection is referred to as dial-up networking-establishing a network connection between your Red Hat Linux PC and another network (such as the Internet) through a dial-up modem. In this case, the maximum data-transfer rate is 56 Kbps. Most dial-up users connect to their ISP using PPP; SLIP is rarely used nowadays.

As far as costs go, DSL and cable modem service connect you to the Internet and also act as your ISP-they provide you with an IP address and give you email accounts. If you use a dial-up modem to connect to the Internet, you get the phone line from the phone company and then select a separate ISP who gives you a phone number that you dial and all the other necessary goodies like an IP address and email accounts.

Table 13-1 summarizes these three options for a small office or a home office connecting to the Internet. You can consult that table and select the type of connection that's available to you and that best suits your needs.

Table 13-1: Comparison of Dial-Up, DSL, and Cable
Feature	Dial-Up	DSL	Cable
Equipment	Modem	DSL modem, Ethernet card	Cable modem, Ethernet card
Also Requires	Phone service and an ISP	Phone service and within12,000 to 15,000 feet of central office	Cable TV connection
Connection type	Dial to connect	Always on, dedicated	Always on, Shared
Typical speed	56 Kbps maximum	640 Kbps download, 128 Kbps upload(higher speeds cost more)	1.5 Mbps download, 128 Kbps upload
One-time costs(estimate)	None	Install = $100-200, Equipment = $200-300, May require activation cost	Install = $100-200, Equipment = $200-300
Typical monthly cost (2003)	Phone charges = $20/month, ISP charges = $15-$30/month	$50/month, May require monthly modem lease	$50/month, May require monthly modem lease

Note: Costs vary by region. Costs shown are typical ones for U.S. metropolitan areas.

Connecting with DSL

DSL stands for digital subscriber line. DSL uses your existing phone line to send digital data in addition to the normal analog voice signals (analog means continuously varying whereas digital data is represented by 1s and 0). The phone line goes from your home to a central office where the line connects to the phone company's network-by the way, the connection from your home to the central office is called the local loop. When you sign up for DSL service, the phone company has to hook up your phone line to some special equipment at the central office. That equipment can separate the digital data from the voice. From then on, your phone line can carry digital data that can then be directly sent to an Internet connection at the central office.

Understanding How DSL Works

A special box called a DSL modem takes care of sending digital data from your PC to the phone company's central office over your phone line. Your PC can connect to the Internet with the same phone line that you use for your normal telephone calls-you can make voice calls even as the line is being used for DSL. Figure 13-1 shows a typical DSL connection to the Internet.

Figure 13-1: Connecting to the Internet Using DSL.

Your PC talks to the DSL modem through an Ethernet connection, which means that you need an Ethernet card in your Red Hat Linux system.

Your PC sends digital data over the Ethernet connection to the DSL modem. The DSL modem sends the digital data at different frequencies than those used by the analog voice signals. The voice signals occupy a small portion of all the frequencies that the phone line can carry. DSL uses the higher frequencies to transfer digital data, so both voice and data can travel on the same phone line.

The distance between your home and the central office-the loop length-is a factor in DSL's performance. Unfortunately, the phone line can reliably carry the DSL signals only over a limited distance-typically three miles or less. This means that you can get DSL service only if your home (or office) is located within about three miles of your phone's central office. Your phone company can tell you whether your location can get DSL or not. Often they have a website where you can type in your phone number and get a response about DSL availability. For example, try www.dslavailability.com for U.S. locations.

Learning the DSL Alphabet Soup-ADSL, IDSL, SDSL

So far this chapter has used the term DSL as if there were only one kind of DSL. There are in fact three variants of DSL, each with different features, summarized as follows:

ADSL-Asymmetric DSL, the most common form of DSL, has much higher download speeds (from Internet to your PC) than upload speeds (from your PC to the Internet). ADSL can have download speeds of up to 8 Mbps and upload speeds of up to 1 Mbps. ADSL works best when your location is within about two and a half miles (12,000 feet) of your central office. ADSL service is priced according to the download and upload speeds you want. A popular form of ADSL called G.lite is specifically designed to work on the same line that you use for voice calls. G.lite has a maximum download speed of 1.5 Mbps and maximum upload speed of 512 Kbps.
IDSL-ISDN DSL (ISDN is an older technology called Integrated Services Digital Network) is a special type of DSL that works at distances of up to five miles between your phone and the central office. The downside is that IDSL only offers downstream and upstream speeds of up to 144 Kbps.
SDSL-Symmetric DSL provides the equal download and upload speeds of up to 1.5 Mbps. SDSL is priced according to the speed you want, with the higher speeds costing more. The closer your location is to the phone company's central office, the faster the connection you can get.

DSL speeds are typically specified by two numbers, like this: 1,500/384. The numbers refer to data transfer speeds in kilo bits per second (Kbps, or thousand bits per second). The first number is the download speed, the second the upload. Thus, 1,500/384 means you can expect to download from the Internet at a maximum rate of 1,500 Kbps (or 1.5 Mbps) and upload to the Internet at 384 Kbps. If your phone line's condition is not perfect, you may not get these maximum rates-both ADSL and SDSL adjust the speeds to suit the line conditions.

The price of DSL service depends on which variant-ADSL, IDSL, or SDSL-you select. For most home users, the primary choice is ADSL or, more accurately, the G.lite form of ADSL with transfer speed ratings of 1,500/128.

Setting Up a DSL Connection

To get DSL for your home or business, you have to contact a DSL provider. In addition to your phone company, there are many other DSL providers. No matter who provides the DSL service, some work has to be done at your central office-the place where your phone lines connect to the rest of the phone network. The work involves connecting your phone line to equipment that can work with the DSL modem at your home or office. The central office equipment and the DSL modem at your location can then do whatever magic is needed to send and receive digital data over your phone line.

Because of the need to set up your line at the central office, it takes some time after you place an order to get your line ready for DSL.

The first step for you is to check out the DSL providers who provide service and see if you can actually get the service. Because DSL can work only over certain distances-typically less than 2.5 miles-between your location and the central office, you have to check to see if you are within that distance limit. Contact your phone company to verify this. You may be able to check this on the Web. Try typing into Google (http://www.google.com) the words DSL, availability, and your local phone company's name. You should get a website where you can type in your phone number and learn if DSL is available for your number.

If DSL is available, you can look for the types of service-ADSL versus SDSL-and the pricing. The price depends on the download and upload speeds you want. Sometimes phone companies offer a simple residential DSL that's basically the G.lite form of ADSL with 1,500/128 speed rating-meaning that you can download at 1,500 Kbps and upload at 128 Kbps. Of course, these are the maximums, and your mileage may vary.

After selecting the type of DSL service and provider, you can place an order and have the provider install the necessary equipment at your home or office. Figure 13-2 shows a sample connection diagram for typical residential DSL.

Figure 13-2: Typical Residential DSL Connection.

Here are some key points to note in Figure 13-2:

Connect your DSL modem's data connection to the phone jack on a wall plate.
Connect the DSL modem's Ethernet connection to the Ethernet card on your PC.

When you connect other telephones or fax machines on the same phone line, install a microfilter between the wall plate and each of these devices.

Insider Insight

Because the same phone line carries both voice signals and DSL data, you need the microfilters to protect the DSL data from possible interference. You can buy them at electronic stores or from the DSL provider.

When you connect your Red Hat Linux PC to the Internet using DSL, the connection is always on and there is more potential for outsiders to break into the PC. You should make sure that the Red Hat Linux firewall setting is set at High Security. To configure the firewall settings, select Main Menu>System Settings>Security Level from the GNOME desktop.

There is another way to protect your Red Hat Linux system from intruders and, as an added bonus, share the high-speed connection with other PCs in a local area network (LAN). To do this you need a router that can perform network address dtranslation (NAT). The NAT router translates private Internet Protocol (IP) addresses from an internal LAN into a single public IP address and makes it possible for all the internal PCs to access the Internet. If you use a NAT router, be sure to change the administrator password from the default password after you install the router.

If you also want to set up a local area network, you'd need an Ethernet hub to connect the other PCs to the network. Figure 13-3 shows a typical setup the connects a LAN to the Internet through a NAT router and a DSL modem.

Figure 13-3: Connecting a LAN to Internet through a NAT Router and DSL Modem.

Here are the points to note when setting up a connection like the one shown in Figure 13-3:

You need a NAT router with two 10Base-T Ethernet ports (the 10Base-T port looks like a large phone jack, also known as RJ-45 jack). Typically one Ethernet port is labeled Internet (or External or WAN for Wide Area Network) and the other one is labeled Local or LAN (for Local Area Network).
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 want to connect to your LAN.
Connect the Ethernet port of the DSL modem to the Internet port of the NAT router using a 10Base-T Ethernet cable (these look like phone wires with 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 10Base-T Ethernet cable.

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

Insider Insight

You can also buy NAT router with built-in 4- or 8-port Ethernet hub. With combined router/hub, you need only one box to set up a LAN and connect it to Internet with a DSL modem. These boxes are typically sold under the name Cable/DSL router because they work with both DSL and cable modem.

Connecting with Cable Modem

Cable TV companies also offer high-speed Internet access over the same coaxial cable that carries television signals to your home. After the cable company installs the necessary equipment at their facility to send and receive digital data over the coaxial cables, customers can sign up for cable Internet service. You can then get high-speed Internet access over the same cable that delivers cable TV signals to your home.

Understanding How a Cable Modem Works

A box called a cable modem is at the heart of Internet access over the cable TV network. The cable modem takes digital data from your PC's Ethernet card and puts in an unused block of frequency (think of it as another TV channel, but instead of pictures and sound, this channel carries digital data).

The cable modem places upstream data-data that's being sent from your PC to the Internet-in a different channel from that used for the downstream data that's coming from the Internet to your PC. By design, the speed of downstream data transfers is much higher than upstream transfers. The assumption is that people download far more stuff from the Internet than they upload. Probably true for most of us.

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 another frequency band.

At the other end of your cable connection to the Internet is a cable modem termination system (CMTS) that your cable company installs at their central facility. The CMTS connects the cable TV network to the Internet. It also extracts the digital upstream data sent by your cable modem (and by your neighbors as well) and sends them to the Internet. The CMTS also puts digital data into the upstream channels so that your cable modem can extract that data and provide it to your PC via the Ethernet card. Figure 13-4 illustrates how cable companies provide high-speed Internet access over their cable TV network.

Figure 13-4: High-Speed Internet Access over the Cable TV Network.

Cable modems can receive downstream data at the rate of about 30 Mbps and send data at around 3 Mbps upstream. 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.

In practice, with cable modem you can get downstream transfer rates of around 1.5 Mbps and upstream rates of 128 Kbps.

Insider Insight

If you want to check your downstream transfer speed, go to http://bandwidthplace .com/speedtest, and click the link to start the test. For my cable modem connection, the tests reported a downstream transfer rate of about 1.4 Mbps on good days.

Setting Up a Cable Modem Connection

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 like no installation fee or a reduced rate for three months. Look for these offers. If you are lucky, they 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 set up at their 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 13-5 shows a typical cable modem hookup.

Figure 13-5: Splitting the Cable TV Signal between the TV and the Cable Modem.

The cable modem connects to an Ethernet card in your PC. So you need an Ethernet card in your PC. The cable company technician often provides an Ethernet card.

Here are some key points to note about the cable modem setup in Figure 13-5:

Split the incoming cable TV signal into two parts by using a 2-way splitter (the cable company technician installs this). By the way, the 2-way splitter should be rated for 1 GHz; otherwise, it may not pass through the frequencies that contain the downstream data from the Internet.
Connect one of the video output from the splitter to your cable modem's F-type video connector using a coaxial cable.
Connect the cable modem's 10 Base-T Ethernet connection to the Ethernet card on your PC.

Connect your TV to the other video output from the 2-way splitter.

Caution

When you use cable modem to connect your Red Hat Linux PC to the Internet, the connection is always on, so there is more chance that someone may try to break into the PC. You should set the firewall setting to High Security. To configure the firewall settings, select Main Menu>System Settings>Security Level from the GNOME desktop.

You may want to add a NAT (network address translation) router between your PC and the cable modem. 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 can do the job with only one box. By the way, the NAT router/hubs are typically sold under the name cable/DSL router because they work with both DSL and cable modems.

The NAT router translates private Internet Protocol (IP) addresses into a public IP address. When connected through a NAT router, any PC in the internal LAN can access the Internet as if it has its own unique IP address. The end result is that a single Internet connection is shared among many PCs. This can be an ideal solution for connecting a small LAN to the Internet.

Figure 13-6 shows what a typical setup with a cable modem connection being shared by a number of PCs in a LAN.

Figure 13-6: Sharing a Cable Modem Internet Connection with Several PCs in a LAN.

Here are the points to note when setting up a connection like the one shown in Figure 13-6:

You need a cable/DSL NAT router with two 10Base-T Ethernet ports (the 10Base-T port looks like a large phone jack-it's also known as a RJ-45 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 want to connect to your local area network.
Consider buying a single box that acts as a NAT router and also 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 10Base-T 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 10Base-T Ethernet cable.
Now connect each of the PCs to the Ethernet hub. Of course, each PC must have an Ethernet card.