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Enabling Security Features on a Linksys WAP11 802.11b AP, Linksys BEFW11SR 802.11b AP/Router, WRT54G 802.11b/g AP/Router, and D-Link DI-624 AirPlus 2.4GHz

Xtreme G Wireless Router with 4-Port Switch

These have been consolidated because they are the recommendations for securing any AP/router and are not specific to a particular hardware.

• Assigning a unique SSID to your wireless network is the first security measure that you should take. Any attacker with a “default” configuration profile is able to associate with an access point that has a default SSID. While assigning a unique SSID in and of itself doesn’t offer much protection, it is one layer in your wireless defense.

• Many attackers use active wireless scanners to discover target wireless networks. Active scanners rely on the access point beacon to locate it. This beacon broadcasts the SSID to any device that requests it. Disabling SSID broadcast makes your access point “invisible” to active scanners. Because your access point can still be discovered by passive wireless scanners, this step should be used in conjunction with other security measures.

• Wired Equivalent Privacy (WEP) encryption, at a minimum, should be used on your home wireless network. Although there are tools available that make it possible to crack WEP, the amount of traffic that needs to be generated make it unlikely an attacker will take the time to do so on a home, or low-traffic, network. Adequate security for these networks is provided by 128-bit WEP.

• Filtering by Media Access Control (MAC) address allows only wireless cards that you specifically designate to access your wireless network. Again, it is possible to spoof MAC addresses, therefore you shouldn’t rely on MAC address filtering exclusively. It should be part of your overall security posture.

• Each of the four security steps presented in this chapter can be defeated. Fortunately, for most home users they do provide adequate security for a wireless network. By enacting a four-layer security posture on your wireless network, you have made it more difficult for an attacker to gain access to your network. Because the likelihood of a strong “return” on the attacker’s time investment would be low, he is likely to move on to an easier target. Don’t allow your wireless network to be a target of convenience.

Configuring Security Features on Wireless Clients

• Windows XP clients are configured using the Wireless Connection Properties and the Windows XP Wireless Client Manager. To associate with your access point once the security features have been enabled, your access point must be added as a Preferred Network. You need to enter the SSID and the WEP key during the configuration process.

• Windows 2000 does not have a built-in wireless client manager like Windows XP. You need to enter the SSID and WEP key into a profile in the client manager software that shipped with your wireless card.

• Linux users need to configure the /etc/pcmcia/wireless.opts file in order to access a wireless network with the security features enabled. The SSID and WEP key need to be entered in the appropriate section of the /etc/pcmcia/wireless.opts file. Restarting PCMCIA services or rebooting allows these settings to take effect.