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Staying Safe on Public Wi-Fi

Use café and airport Wi-Fi without handing your data to strangers.

What HTTPS Does for You

Public Wi-Fi is any network you share with strangers, like at a café, library, hotel or airport. Many have no password, or one posted on the wall for everyone. On those networks, other people may be able to see some of what you send.

The good news is that most of what you do today is already protected by HTTPS. HTTPS is the secure way websites talk to your browser. It encrypts, or scrambles, everything between your device and the website. Someone else on the café Wi-Fi can't read your passwords, messages or bank details on an HTTPS site.

Most browsers show a small icon next to the web address for a secure site, and warn you loudly when a site isn't secure. Most apps on your phone and computer also use encryption behind the scenes.

HTTPS still leaves a few things open:

• Others on the network can often tell which sites you visit, even if they can't see what you do there.
• A rare site without HTTPS is not protected at all. Don't type passwords there.
• HTTPS can't help if you join a fake network and then type your password into a fake page.

So the rules are simple. Check for the secure icon before signing in. Never click past a browser warning that says the connection isn't private. If something feels off, wait until you're on a network you trust.

Windows also helps. When you join a new network, check that its network profile type is Public network, in Settings > Network & internet > Wi-Fi, under that network's properties. That hides your computer from other devices there. On a Mac, the firewall in System Settings > Network does a similar job.

Evil Twins, Hotspots and VPNs

An evil twin is a fake Wi-Fi network set up by a scammer, named to look like a real one. At a café called Sunny Beans, you might see "Sunny Beans WiFi" and "Sunny Beans Free WiFi". One could be a trap. If you join it, the scammer controls your connection and may show fake sign-in pages.

• Ask staff for the exact network name before joining.
• Be wary of a sign-in page that asks for your email password or card details just to get online.
• When you're done, forget the network. Forgetting tells your device to stop joining it automatically. A scammer can copy a common name, and your device might join the copy later by itself. In Windows, go to Settings > Network & internet > Wi-Fi > Manage known networks.

A simple way to skip the risk is your phone's hotspot. A hotspot lets your phone share its mobile data with your laptop over its own private Wi-Fi. It uses your data plan, but you control the network and its password.

You met VPNs in Mobile Networking. A VPN, short for virtual private network, wraps all your traffic in an encrypted tunnel to the VPN company's servers. On public Wi-Fi, it hides which sites you visit from others on that network.

A VPN doesn't do everything:

• It doesn't stop phishing pages, malware or bad passwords.
• The VPN company can see your traffic instead, so choose a trusted one.
• It doesn't make you anonymous to the sites you sign in to.