How to stay private on public Wi-Fi

File photo: A woman walks past a WiFi-enabled phone booth in New York July 12, 2012. (REUTERS/Keith Bedford)

If I've said it once, I've said it a thousand times: Avoid doing anything you would not want anyone in the world to know on public Wi-Fi. You may think you're safe in that busy café or big-name hotel, but public Wi-Fi is a major liability.

No matter how safe the connection seems to be, your computer is vulnerable to hackers, because you have no idea who is in charge of that router or who has access to it and the data that passes through it. Knowledge is power. Click here to learn how crooks attack your computer on public Wi-Fi.

There are lots of ways to protect yourself, of course. Your best defense is a virtual private network (VPN), which can prevent nosy strangers from snooping on your browser. You can also employ the usual firewalls and antivirus software to defend your computer from hackers and malware. Click here to learn more about VPNs and safe browsing on public Wi-Fi.

Even the best security systems have their weaknesses, and you have likely never heard of this one: File sharing on a public network can expose your computer to data thieves.

This is a scary problem, because you may not even realize that you’re sharing files. But if your computer is on the wrong setting, you may attract any number of cybercriminals. So how do you make sure your computer isn’t leaking information?

File sharing

File sharing is very handy, especially for groups of people. Whether you’re using iCloud, Dropbox or Google Drive, file sharing allows a large team to work on a single project at once … or families to browse digital photo albums … or data specialists to organize large batches of information. This is very convenient, as long as you’re on your own secure network.

But if you’re sharing files on public Wi-Fi, your folders may be accessible to anyone connected to the same network. In other words, file sharing automatically exposes your computer and everything you intend to share. Your vacation photos may end up in the wrong hands. So could your contracts, spreadsheets and tax information.

In fact, you don't have to be a hacker to take advantage of shared folders. Anyone who looks around their network folders can instantly run a search and find unguarded files.

It works the other way around, too.

An attacker can also set up a shared folder with malicious files. You may stumble into the mysterious folder and think, “Wait a minute, where did this come from?” Then you click on it and release the malware onto your desktop. There are other ways you can get into trouble. Click here to learn how to avoid getting hacked on the road.

Want to ensure your privacy? Make sure to turn off file sharing before you connect to public Wi-Fi. Here’s how to do it:

Turn off file sharing on Windows:

1. Search for "Control Panel," then click on the best match to open it.

2. Under "Network and Internet," click on "View network status and tasks."

3. On the next page, click "Change advanced sharing settings."

4. Under "File and printer sharing," tick off "Turn off file and printer sharing."

5. To prevent network snoopers from seeing your computer, tick off "Turn off network discovery" too.

6. Save changes.

Turn off file sharing on a Mac:

1. Open your Mac's System Preferences (the gear icon in your dock).

2. Click on the "Sharing" icon.

3. On the next "Sharing Page," uncheck File Sharing.

4. I also recommend that you uncheck all the other sharing services here when connecting to public Wi-Fi.

5. Close the window and you're set.

Turn file sharing back on

OK, you’ve done your business and can log off of public Wi-Fi now. You took all the necessary precautions, and there’s a good chance none of your information was compromised.

Just remember to switch your file sharing back on when you get back to your home or office. None of these services will work unless you restore your regular settings. When you’re back on your secure server, you can continue sharing to your heart’s content.

How else can you protect yourself from digital intrusion? Be sure to listen to or download my podcasts, or click here to find it on your local radio station. You can listen to the Kim Komando Show on your phone, tablet or computer. From buying advice to digital life issues, click here for my free podcasts.

Learn about all the latest technology on the Kim Komando Show, the nation's largest weekend radio talk show. Kim takes calls and dispenses advice on today's digital lifestyle, from smartphones and tablets to online privacy and data hacks. For her daily tips, free newsletters and more, visit her website at Komando.com.