Small Wi-Fi networks that allow guest user access are open to very big security holes. They needn't be, though: Here's a quick way to clamp down on potential threats.
If your home or office network allows guest users, it's got big potential problem. On a typical WiFi network, every device on the network can communicate with every other device. That means that if a guest logs with malicious intent, he can attack other devices on the network, including network shared files and folders. And there's a danger even if the guest isn't a malicious one, because if the device is infected with malware, that malware can infect the other devices on your network -- notably yours.
There is a solution, though: You can isolate guests from everything else on the network, or if your router can't do that, you can isolate the devices from each other. Isolating guests only is called guest access, guest network, guest isolation, or creating guest zone. Isolating all devices from each other is called wireless isolation.
Ideally, you'd like to create a guest network. That's because when you use wireless isolation, even your devices can't communicate with each other, which can be problematic. Unfortunately, though, most routers don't let you create guest networks.
Linksys, though, has a router line called Linksys Smart Wi-Fi Routers that let you create a guest network, in addition to other nifty features. If you've got one of those routers, there are two ways to create a guest network -- one over the Web, and one using mobile apps.
To do it over the Web, log into your Linksys router by going to 192.168.1.1 or myrouter.local in your browser's address bar, pressing Enter, and then clicking "click here" underneath the Sign In button. Enter your router password (the default is "admin".) From the page that appears, click Guest Access. Just fill in the form, including setting a password for it, and you're done. You'll have to give your guests the password that you've created for them to access the network.
To do it via a mobile app, go to linksyssmartwifi.com and create a Linksys Smart Wi-Fi account. After you do that, head to either Google Play or the App Store depending on whether you have an Android or iOS device, and get the Linksys Smart Wi-Fi app. You'll be able to create a guest account using it.
If your router doesn't have a guest network, you'll have to use its wireless isolation feature -- that is, if it has one. Many routers, including some Linksys and Netgear routers, have this feature, although it's not always easy to find.
For Linksys, log into your router and go to Wireless --> Advanced Wireless Settings and look at the top of the screen for the AP Isolation setting. Turn it to Enabled. That does the trick. On a Netgear router, go to the main Wireless Setting page, and click the box next to "Wireless Isolation."
Again, keep in mind that doing this limits your devices' access to each other. And it can potentially cause other problems as well, including blocking Google Chromecast from working. But it'll keep you safer if you give guest access to people.