More and more, when people connect to the Internet, they're not connecting via wires. Instead, they're connecting wirelessly. A transceiver in their laptop or desktop computer communicates with a wireless device called an access point or router, which gives them access to the Internet.
Home networks are mainly wireless rather than wired. In fact, it's difficult these days to even find a router for your home that is wired rather than wireless. Wireless home routers commonly include ports for connecting PCs with wires as well as wirelessly, so there's no need to buy a wired-only router.
In addition to connecting at home, more and more corporations are setting up wireless networks. They do it because it's much cheaper to set up a wireless network than a wired one, and it's more convenient for users because they can connect to the Internet and corporate network anywhere in the building, not just when they're next to an Ethernet port.
People also connect to the Internet when they travel, by using hotspots at cafes, airports, and other locations.
This wireless technology is called Wi-Fi. It is not a single standard. It refers to an entire family of standards based on the 802.11 networking protocol. There are multiple 802.11 standards: the now little-used 802.11a; 802.11b; the higher-speed 802.11g; and the highest-speed (as of this writing) 802.11n. As this book went to press, the final 802.11n standard had not been formally adopted, but some "pre-n" Wi-Fi equipment was being sold.
With all of Wi-Fi's convenience comes dangers. The same technology that lets you browse the Web from your back porch can let invaders hop onto your network from outside your house or apartment.
By its very nature, Wi-Fi is an open technology. A wireless router broadcasts its presence to any device with a Wi-Fi adapter within its range, and if the router is unprotected, anyone who wants to can connect to it and use the network. That makes it easy for intruders to get in.
A common kind of intruder is called a war driver. This person drives through areas of cities and suburbs known for having Wi-Fi networks and searches for unprotected networks he can break in to. He uses software that makes it easy to find unprotected networks. Some war drivers use high-power antennas so they can find as many networks as possible. But, in fact, they don't even need this kind of equipment to get into networks. Software built directly in to Windows XP, for example, lets anyone easily find and connect to an unprotected network.
When war drivers target a business network, they may be looking for proprietary business information or be looking to do malicious damage. When they target a home network, they might look for personal information, such as credit card numbers, or be looking to damage computers.
But Wi-Fi intruders can cause other problemsand these may be even more serious than stealing information or damaging computers. They can use the network for illegal activities, and if those activities are uncovered, it will look as if the owner of the network is guilty because the war driver will be long gone.