I live in an apartment complex, and I have found that some folks leave their wireless routers open for anyone to join. In addition, for those that are "locked down," the default password was never changed. Why is this? Well networking computers used to be a difficult task, but with today's advanced routers and OSs, it's easy to setup your own network -- and cheap too.
You can go down to your favorite "big box" retailer and for less than $50 pick up a fast wireless router. If you already have cable Internet access, just plug-in the router, and it works (DSL requires some configuration). Unfortunately for the non-geek crowd, they are leaving themselves open to anyone who wants to access their network and the computers that are connected to it.
"How?" you might ask. First, go to Google and search on "router default passwords" and click on "I'm Feeling Lucky" (or click on "Google Search" and then click on one of the many search results). You will be taken to a site with default passwords for routers. So for folks who just plugged their router in (or who even added network security, but did not changed their default password), their system is open for anyone to use, because all the default usernames and passwords are easy to find in one place. (The usernames and passwords are also in your user manuals, so if they were not all in one place, a simple visit to the manufacturer's website would reveal them too.)
In addition to now giving anyone the ability to configure your router to their liking, it can get worse. Take for example the files and folders you shared on your computer for your family to access, now that you have a home network. Now since anyone who can get on your network can see these, you have shared them with the entire world. Perhaps you haven't shared any files or folders or you have required a password to access them. Still, that may not be enough.
Most users of Windows XP do not realize that it comes shipped with a default administrator username and password, too, therefore it has never changed either. Well once someone has breached (err accessed) your home network, it doesn't take much more effort to access your Windows XP computer. For example, I was able to learn my neighbors favorite music and see photos of their friends and family by using this technique. (I didn't look further, really I didn't -- I just wanted to prove that this is a problem.)
To recap, here's what you want to make sure you do when setting up your home network:
- Change the default username and password on your router.
- Change the default username and password for your OS (here's instructions for Windows XP).
- Secure your wireless connection with WPA (or WPA2).
- Only share unsecure files and folders that are okay for anyone to access. Require a login for sensative files.
- Cook your geeky brother-in-law a nice dinner for all his hard work.