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What Is a Public Network and Why Is It Dangerous?

You’ve probably heard that a public network such as public WiFi isn’t safe to connect to. At the same time, you’ll find dozens of apps dedicated to helping you find free WiFi. Even Facebook offers to help you find it if you enable the option in the app. It makes you second guess just what a public network is and which types are safe, and which aren’t.

Public Network

In simple terms a public network is a network, wireless or wired, that computers and devices you don’t trust are connected to. The term has been around for a while but Windows users are more familiar with it. In Windows 7, whenever you connect to a network, it asks you if it’s a public network, or a home network. The distinction that the OS draws between the two is that on a public network, you can’t trust all the other computers on it.

By this definition, public WiFi which forms a public wireless network isn’t safe. This also means a LAN at your university isn’t safe either even though it’s restricted to on-campus use. The same holds true for the free WiFi you use at airports and bus terminals. The free WiFi you use at your favorite coffee shop falls into this same category.

A private network, or as some might call it a ‘home’ network is one where you know every single computer and device that’s on it. The WiFi network at your home creates a private wireless network. Likewise, the WiFi network or the LAN at your workplace creates a private network as well.

File Sharing Over Public Networks

Generally speaking, both Windows and macOS do not allows systems to share files over public networks. macOS has a feature called AirDrop that lets you share files with anyone regardless if you’re on a public or private network but you need to enable that particular mode of sharing. By default, AirDrop on macOS restricts file sharing to your trusted contacts.

The Windows 10 Spring Update is expected to add a similar feature called Nearby Sharing. It too will let you share files with anyone on the same network however, it has safety features that prevent unknown systems from sending you files.

File sharing over a public network is generally considered dangerous not just because the files can be malicious but also because your system is somewhat open and more accessible when it is visible on the network to everyone else. If you want to share files over a public network, it’s best to use cloud drives instead of sending files over the network itself, or to use a secure sharing method like AirDrop on macOS.

Staying Safe

There are a few basic things you ought to do to keep yourself reasonably safe on a public network.

Disable Sharing & Discovery

To stay safe on a public network, you should first and foremost, disable sharing over the network. On Windows 10, you can do this from the Settings app under Network & Internet>Status. Here you will find several network settings that you can manage, including one for Sharing.

Click it, and it will take you to the Control Panel where you can disable network discovery and sharing.

On macOS, you can disable sharing and discovery from the System Preferences under Sharing. While you’re at it, restrict AirDrop or maybe keep it off unless you need it.

Enable Firewall

All operating systems come with a firewall that protects your system from threats on the network. On Windows 10, this firewall is Windows Defender which some users are tempted to turn off. Whatever OS you’re on, make sure you’ve enabled the firewall if you connect to public networks often.


A VPN is a reasonably good way to protect your system from malicious network traffic. A good VPN will encrypt your web requests and that in turn will give you better security. Your activity will be segregated so while you’re on a public network, you will be using it from a private one. If someone were to attempt to access your system, they’d have to get through an extra layer of security.

Updated Browsers & Safe Browsing

A threat over a public network usually comes from other systems and devices but it can also come from accessing unsafe websites or from using an outdated browser. Make sure your browser is up to date so that it can provide you basic protection and stick to visiting reliable websites that use HTTPS.

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