With the availability of public hot spots and neighborhood wireless (WiFi) networks springing up in every direction, you might wonder if using someone else's wireless Internet service is secure. What exactly can Starbucks, a municipal network, or your neighbor see if you hop on to their networks? If they want, they might be able to see nearly everything that travels between your laptop and the network’s router.

Using someone else's wireless Internet service or even your own can create additional risks. When information is broadcast between a laptop and wireless router, anyone within range can use packet-sniffing software to pick up the broadcast. Someone listening in can trap usernames and passwords, email and file transfers. Only a connection made to a secure website remains secure, even across such a network, because the encryption originates at the website and extends to the user’s computer.

To secure a wireless LAN from local eavesdropping, all information that travels between the laptop and router must be encrypted using software security options built into the wireless router. In this case the entire LAN broadcasts in an encrypted format. The router only decrypts LAN traffic to send it on to the Internet. This does not make surfing the Internet any more secure than it otherwise is, but it does eliminate risks associated with potential eavesdropping on the LAN side.

Securing a wireless network also prevents “hitchhikers” from parking within range of the network, then using the wireless LAN to connect to the Internet. WiFi networks that are encrypted require a username and password to gain access, preventing freeloading.

Many municipalities now provide free wireless access for residents and visitors, which commonly requires parking in a certain part of town to be within range. These types of networks are rarely encrypted because requiring a password and username restricts accessibility. Many local neighborhood networks are also unsecured, as are some corporate networks. In cases like these, using someone else's wireless Internet service does open you up to risk.

To increase personal security while maximizing the convenience of using third party networks, avoid using a single username and password for all of your needs. When networking from a secure location, assign unique usernames and passwords for each registered site, for email, for banking, shopping and other needs. Web browsers like Mozilla™ Firefox™ can remember website usernames and passwords for you, keeping them encrypted locally for safety, then filling them in automatically when you visit a site. It is also advisable to occasionally change usernames and passwords associated with sensitive accounts.

Security schemes designed to protect privacy and personal information will not protect those using someone else's wireless Internet service for illegal purposes. Every network adapter, for example, has a unique MAC address which the computer reveals every time it connects to a network. It is a relatively trivial matter in most cases to trace that MAC address back to a real world user by various means, should authorities be motivated to do so.

Knowing that using someone else's wireless Internet service can be risky, it might be wise to limit your activities on unencrypted networks accordingly. When possible, avoid visiting sites that require a username and password, and put off sending or collecting sensitive email or files until you can connect from a secure location.