When you are on a wireless network, most other wireless enabled machines (Handhelds, Bluetooth enabled devices, WAP enabled PDAs, Laptop computers, Wireless Scanners, Wireless Access Points, packet Sniffers, etc.) in your general proximity can see you in their network neighborhood, and possibly access any resources (file and print sharing services, data off your disk drives, etc.) being "shared" your system. Often when such a breach occurs over the air, there are usually no visible signs of any such an intrusion taking place. All one would probably see is possibly the mouse pointer changing to an hour glass, along with some seemingly benign/random activity on one's disk drives.

A machine so linking up with your unprotected wireless enabled system can do quite a bit of damage -it can possibly infect your system with a virus or a worm, plant a backdoor for a return visit, or simply walk away with your confidential data.

If you have on your computer a decent anti-virus software that is regularly updated with the most recent vendor-supplied virus updates, and if you patch up the operating system on your PC regularly, you probably would not have much to worry about as far as the computer virii and computer worms are concerned. If you have information that someone would be really interested in, the only fail-safe way to protect your sensitive data is to unplug your wireless adapter.

Wireless Encryption Protocol (WEP) and other wireless security protocols are usually quite effective in discouraging casual lookers away. Kind of like how a lock on steering wheel makes your car just a tad little less inviting to those car thieves. If someone is "seriously" interested in your data, they may be able to get to it if were to you remain on-air for a significantly long duration. Often all they have to do is to silently collect a significantly large number of data packets traveling between your system and the device (such as an access point, a WAP enabled router, or a bridge) that may be upstream from it, and reverse engineer it. Considering that most wireless devices send out initial authentication data (including SSID, MAC, and in many cases even your username and password) in clear text, often it is a matter of time.

Therefore, just because your hotel has a wep-secured wireless network, it would not be prudent to assume that the wireless network (WLAN) that you may be merrily connecting to is any safer than an open network. WEP enabled networks may be "idiot-proof", but they are far from being "fool-proof." Most computer security professionals would consider the security provided by wep-enabled devices to be a borderline case of disillusion of security -at best. Just because WEP enabled devices are just a little bit harder to break into, it would not be prudent for one to lower the guards when it comes to sharing with others a wireless network at a hotel, a motel, a convention center, or even at your corner coffee-shop.