Beating the wireless blues

Solve network problems that cross property lines

Even if your Wi-Fi network has glorious coverage one day, it might act up the next. The problem might be good neighbors running bad Wi-Fi technology.

All equipment that operates in the 2.4-GHz band (including Wi-Fi hardware) is designed to minimize interference with other devices using that band -- such as cordless phones. Wi-Fi equipment has to sort out usable signals from the radio mishmash in the air. But some Wi-Fi chip sets don't play nicely with others.

For example, chip maker Broadcom Corp. last year released test results that it says show chips made by its rival, Atheros Communications Inc., interfere with other wireless network devices. Broadcom supplies 802.11g chips to Apple, Belkin Corp., Buffalo, Linksys Group Inc., and Motorola Inc., as well as to Dell Inc., EMachines, and Fujitsu Ltd. for their laptops. Atheros technology is found in most D-Link Inc. and NetGear Inc. gateways and devices.

The problem, Broadcom alleges, stems from a proprietary Turbo setting available on Atheros-based gateways; this setting doubles the raw speed of the link if you use another Atheros-based device.

Atheros says that its engineers don't detect interference problems from its chips. CEO and president Craig Barrat says, "You can argue that the aggregate amount of interference generated is roughly unchanged." Barrat also says the company stands by its claim that its chips comply with FCC regulations. Grimm of the Wi-Fi Alliance says, "We're currently studying the issue of potential interference from channel-bonded 802.11g products in the lab."

So if your neighbor has Atheros-based equipment with Turbo mode, you might need to have a chat -- if you can figure out who's responsible. Conversely, if you use Atheros-based gear, you might get a knock on the door from a neighbor asking, "Did you just install a new gateway?"

In any case, you could cut some of the interference if you and your neighbors agree to set the gateways to use different channels. But if you can't track down your interfering neighbor, and changing channels doesn't help, consider installing a directional antenna. Such an antenna in the right part of your house and aimed at the rest of it should boost your gateway enough to overcome the interference, without ruining anyone else's good time.

Improve wi-fi security

Wi-fi earned a reputation early on as an insecure technology to link machines in a LAN. Most Wi-Fi devices ship with security features disabled, so anyone with a Wi-Fi-enabled laptop or PDA can park outside your home or place of business and access your wireless network.

The first line of defense, known as Wired Equivalent Privacy (WEP), didn't meet the security test. WEP is built into every Wi-Fi device, and using it is better than nothing, but its encryption routines are flawed. WEP keeps casual snoops at bay, though widely available software will let a serious intruder break a WEP key in as little as 15 minutes on a busy network.

You can limit access to your network by using Media Access Control (MAC) address filtering on your gateway, where you restrict access based on a unique code that's built into every Wi-Fi adapter (and ethernet adapter, for that matter).

MAC filtering may keep out neophyte hackers, but it also isn't foolproof: Since MAC addresses are sent in the clear even when you encrypt, a competent snoop can defeat MAC filtering easily.

Instead of relying solely on MAC filtering, combine its use with WEP's replacement, Wi-Fi Protected Access (WPA). WPA fixes all the broken parts of WEP, and it comes built-in on any Wi-Fia??certified device that's been released since September 2003. WPA firmware upgrades are available for many (but not all) older 802.11b gear sold between 1999 and 2002. Check the manufacturer's Web site for more information about your particular brand of card and gateway.

For Windows XP, you must download a patch before you can use WPA, though newer PCs may ship with the patch installed. The patch adds basic support for WPA in the operating system, along with several other new technologies that are required for WPA to work correctly.

Laptops with Intel Corp.'s Centrino mobile wireless technology will also let you install the WPA patch; but even though Intel has released updated drivers, individual laptop manufacturers have to integrate those drivers into their versions of Windows XP before WPA will work on them. Check with your notebook manufacturer's tech support to find out whether, and how, to upgrade. Intel's new 802.11g Centrino adapter, due to appear in laptops this year, will fully support WPA without extra downloads or patches.

When you use WPA, you protect your network with a passphrase (a longish password, from 8 to 63 characters in length). You enter the passphrase into a WPA configuration page on your gateway; thereafter, anyone who wants to connect enters the same passphrase into the Wi-Fi card settings. Without the passphrase, a would-be user can't connect.

To enter the WPA passphrase into your Wireless Network Connections profile, double-click My Network Places, then click View Network Connections in the left pane. Right-click your Wi-Fi network connection, select Properties, and double-click an existing network in the Preferred Networks pane (in the lower half of the Properties dialog box). In the Association tab, choose WPA-PSK from the Network Authentication pop-up menu. (Unless you're on a business network, don't choose the plain WPA option.) In the Data Encryption pop-up menu, select TKIP, enter your WPA passphrase twice, and click OK to save the profile.

One proviso with WPA: Though this privacy standard is highly secure, a researcher reported in late 2003 that a passphrase less than 20 characters long composed entirely of words could be cracked. Use a longer passphrase, and include some punctuation marks or numbers for maximum security.

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Glenn Fleishman

PC World (US online)

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