As growing numbers of corporations deploy Wireless LANs with 802.11a or 802.11b, Windows users are finding more Network Interface Cards in their notebook computers. For instance, there may be a PC Card that is a wireless NIC. You may also have a built-in 10/100 Ethernet adapter or an additional Ethernet PC Card. There is usually a 10/100 Ethernet adapter built into the notebook's docking station as well.

Generally the network cards that require cables but don't have cables attached are mostly harmless, as in the case where you use an Ethernet adapter in the docking station in the office, and during this period, the Ethernet adapter in the laptop is not plugged in. However, if you or users you support take your laptops home and plug the Ethernet adapter into a cable modem, or use the modem to dialup the Internet, this does not disable any wireless LAN adapters you may have installed. This means that your laptop may be vulnerable to a network-based attack through this adapter and it wouldn't enjoy the normal protection from your corporate firewall.

This situation would be particularly risky if you travel to other business offices regularly. Your laptop may connect to that wireless LAN without your knowledge, giving potential competitors or partners access to the confidential information on your hard drive.

A simple answer to this problem is to disable the adapter when it's not in use. Do this by right-clicking on the adapter's icon in the systray at the bottom right of the screen. However, this manual action is annoying and easy to forget.

If your configuration permits, consider adding hardware profiles as appropriate and disabling the unused adapters in each profile. You can access these in Windows 2000 from the System Properties dialog, on the Hardware tab. This will allow you to choose at bootup, which adapters to enable and which to disable.

While you're at it, you want to configure the Infrared port as well, to make sure that it requires a user to acknowledge any transfers of data before they take place.

Thomas Alexander Lancaster IV is a consultant and author with over ten years experience in the networking industry, focused on Internet infrastructure.