my internet conection is being stolen?

These are all great answers but I wanted to share my approach. In my opinion, no single solution will keep you safe, using WPA or WPA2 is your best bet.

My approach to wireless network security has five main points:

1) Change your encryption to WPA or WPA2. This is the hardest for your neighbors to deal with. The fact is that the only way that people have been able to break into these is with a dictionary attack, so with a known word or phrase, which leads me to point #2.

2) Choose a lengthy encryption key: Use upper case, lower case and numeric characters. I use the generator in the sources section to generate random 63 character keys. I then will put that key on a USB drive to install on my laptops. I found that emailing the key to my iphone and then copy/paste it into the wireless settings worked well.

3) Use MAC filtering: A MAC address is a 12 digit hexadecimal number that is unique to each network card. The number will look something like this: 00-22-33-EA-43-1C If you can setup MAC filtering on your wireless router, all you have to do is go into the command prompt on your laptop (start, run, cmd.exe) and type in the ipconfig /all command and look for the Physical Address of your wireless adapter. If you are using MAC filtering, an attacker would have to find out what your physical address is and then spoof that address. While this can be done, it does add some security.

4) Change your administration password and only allow administration from a wired port. Additionally, you can setup admin access to use secure http and use a non-standard port as well. Some devices will even let you restrict admin to a specific IP address.

5) Turn off the SSID broadcasts. This won't advertise your SSID so unless you have a wireless network sniffer or a tool like Network Stumbler, they won't see your network. As long as your laptop is configured for this SSID, you'll never notice.

What's that you say? Why yes, when it comes to my wireless routers I AM paranoid.

If you are using WEP encryption that was broken about 5 years ago.

One: Set you router to stop broadcasting the network SSID Name, and change the name.

Two: Use WPA2 with at lease 12 letters/numbers.

Tree: set your router to block a range of IP addresses other then the computer you have.

change to the strongest form of encryption your computers will support [it is o/s dependent] and then change your password.

some routers will let you turn off the SSID broadcast as well. see if yours permits that and if so, do so then change the SSID as well. [you'll have to change it in all your wifi computers and move that new name to the TOP of the network list].

you can even choose a different [oddball] channel.

with a new and unbroadcast SSID and a new, stronger password, you should be good.

also -- some routers can be set to only accept connections to specific computers and devices. this is done by specifying the MAC address of the approved devices/computers. see if you can do this.

8-)

You need to have a network security system with a password. If it continues to happen, call your provider and see what they can do.

they figured out what your code was. if wireless, passkey protection it is extremely easy to hack.