Wireless Networking for Small Businesses - Security Considerations

Unauthorized wireless network access is probably one of the biggest threats to small and medium sized businesses. This is described as a user from outside the company using the network. Unauthorized access can be something as simple as a neighboring business using the wireless LAN to access the Internet. If the unauthorized user is just surfing the Internet it would not present a very big problem except for potentially slowing your network down...

InfosecWriters pdf article by Rusty Morgan. See also wikipedia page on wireless security.