Fix your 10 common Wi-Fi problems(last five)

6. Which wireless channel should I use?
Wireless 802.11b and 802.11g routers have at least 11 channels, and most routers come set to channel 6 as the default. If you experience interference--from a neighbor's router, for instance--you can change your channel to solve the problem. Channels 1, 6, and 11 are non-overlapping channels; other channels overlap a bit. So if your neighbor's network uses channel 6, change your router to 1 or 11. You'll typically find channel settings on the router's basic wireless settings page. Just click the drop-down menu and select an alternate channel, then save the settings.

7. How do I share files on a wireless network?
First, you'll need to set up a workgroup and make sure that all PCs are assigned to the same workgroup. Next, enable file sharing in Windows. First, right-click on the folder you want to share, choose Sharing and Security from the right-click context menu, then click the Sharing tab. Put checks in the boxes labeled "Share this folder on a network" and "Allow network users to change my files" to enable others to modify the documents. Finally, click OK.

8. Should I allow other people to access my Wi-Fi service? What are the dangers?
Some users see no harm in sharing the Wi-Fi love, giving neighbors and even total strangers free access to the Internet. Others maintain that piggybacking can open their networks to potential danger. The decision is yours, but if you choose not to encrypt, make sure to disable file sharing. Assuming you have your hardware firewall turned on, the worst that probably will happen is that your throughput will drop if your piggybacking neighbors crank up BitTorrent every evening. If you want to determine whether others are using your unsecured network, most routers have a page that lists all the wireless clients currently connected.

Most people, however, are not comfortable with the idea of allowing just anyone to use their wireless service. In theory, the practice can make your network vulnerable to hackers, since anyone who uses your wireless signal is on your home network. Malevolent users, for instance, could release nasty viruses or hijack your PC. That's not terribly likely, but you should avoid the possibility by using WPA to protect yourself and keep others off your network.

9. Should I worry about packet sniffers grabbing my information when I browse the Web at public hotspots?
Yes, you should at least consider this possibility, although whether you do anything about it depends on the sensitivity of your data and your level of paranoia. Anyone can install packet-sniffing software that will enable him or her to eavesdrop on what you do at a public hotspot. These snoops can read your emails and see what Web sites you visit, but they will not have access to the files on your laptop, unless you have file sharing enabled. Also, they cannot see any messages or Web pages sent over the secure server connections typically used by banks and e-commerce sites. (Look for https:// in the URL.)

If you use a VPN to access your corporate network, you can use it at hotspots to encrypt all transmissions and shield them from packet sniffers. If you don't have a corporate VPN but frequently use public hotspots, you might consider a consumer VPN service such as the PersonalVPN from Witopia (US$39.99 per year, www.witopia.net) or BlowFish from HotSpotVPN (US$10.88 to US$13.88 per month, www.hotspotvpn.com). These employ powerful 128-bit encryption to protect your data as it is transmitted.

10. What is a hardware firewall? If my router has one, do I need to run the Windows firewall or other third-party firewall software?
Most wireless routers have a hardware firewall that safeguards the network by providing both incoming and outgoing protection. A hardware firewall will include network address translation (NAT) capabilities that make your PC invisible to anyone trying to attack it. If you enable the hardware firewall, you probably don't need a third-party software firewall. You should still run the Windows firewall, however, because it keeps a low profile and will stop basic worms if your PC gets hit by a drive-by downloader.