Chapter 18 discusses setting up a firewall/router, using a Linux distribution designed
specifically for the task.
FIGURE 5-3
A firewall provides a safeguard between your LAN and the Internet.
In this example, the equipment you need includes:
An Ethernet port on each computer plus an extra port for the firewall/router
A LAN cable for each computer
A hub or a switch
A low-end PC (a PC with as little power as a 486 might do) running as a Linux
firewall/router
The DSL or cable modem
An alternative to this wired configuration is to replace the hub or switch with a wireless
access point. Then each computer equipped with a wireless LAN card can get on the network
without wires.
CROSS-REF
ISP
Linux
Linux
firewall/router Hub or switch
NAT
Broadband
connection
DHCP
Mac
Windows
Linux
Linux
183
Getting on the Internet 5
Connecting Servers
So far you??™ve seen configurations that let one or more computers from your home or small business
browse the Web. Allowing someone from the Internet to request services (Web pages, file transfers,
and so forth) from your computers requires some extra thought.
After you have TCP/IP (the primary set of protocols used on the Internet) configured to connect to
your ISP, requests for data can pass in either direction between your computers and the Internet
unless you use a firewall to restrict traffic.
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