You probably know the dangers of using public Wi-Fi at places like Starbucks and the airport. But if you assume your own home Internet is safe, you’d better make sure.

These days, if you buy an Internet router from a store or get one from your Internet service provider, it comes with built-in security features. But if your router is a few years old, it’s likely not secured — which means you could be exposed to hackers every time you surf the Web.

Even if your router is relatively new, take these steps to make sure your home network is secure so online scammers can’t get access to your computer — and possibly steal your passwords, install malware or take personal financial information. If you need help, contact your Internet service provider.

Use a strong password

Your modem, router or both are likely to come with a pre-set password from the manufacturer. You will find it taped to the bottom of the device or in the packing materials. It is likely to have a strong password, that is, a long, randomized string of letters, numbers and symbols.

That should be good enough, but if you want to change it, use a similarly strong password and write it down somewhere near or on the router itself. A weak, guessable password could let strangers ride along on your Internet connection.

Choose secure encryption

Security settings on a home network come in three encryption standards — WEP, WPA or WPA2. WEP was the standard for a long time, and the two WPAs are improvements. Choose WPA2 on the settings page of your router (typically reached by typing a specific IP address into any browser to get to an admin page) if your network is compatible, or step down to WPA if not. If WEP is all that works, you are protected, but you might want to get a new router to be sure you have the highest level of encryption. WEP can be cracked if someone really wants into your network.

Install antivirus and malware protection

You might think that common-sense “safe surfing” practices (don’t open that stranger’s email!) will be enough to protect your network from attack. But spammers and thieves always look for ways to get you to lower your guard. Antivirus and malware protection software can help you avoid the latest threats and deal with them if you happen to make the wrong move online.

Turn on your firewall

Most routers come with a firewall, which blocks unauthorized people from breaking into your network to steal data or install malware. If you are savvy enough to install the router yourself, you can turn on the firewall in the admin settings. (If not, get help from your Internet service provider.)

Your computer’s operating system also has a firewall that’s separate from your router’s firewall. Make sure you turn on the firewall included in your operating system. Here’s how:

In Windows:

  • Click the Start button, then go to the Control Panel
  • Click Security, and then click Windows Firewall
  • Turn firewall on or off (on is recommended), and then click OK

For Apple:

  • From the Apple menu, go to System Preferences
  • Click Security and Privacy, then Firewall
  • Click the lock icon to unlock it, and then type your admin name and password
  • Click Start to turn on the firewall

Just like your operating system has a firewall, your antivirus program also has one. (You don’t need to turn on both.) Usually when you turn on the antivirus software, you’ll be taken to a status page where you can turn on a firewall.

Set up a guest network

There’s no need to share your network login information with every visitor to your home. Most newer routers will allow you to create a second network with its own identity and password for the occasional user, such as in-laws coming for the holidays or your kids’ teenage friends.

Review parental controls

If you have young kids at home, be wary of their “alone time” with your tablet, phone or laptop. An innocent-looking game site can be crammed with third-party content vetted by nobody and ready to deliver malware straight to your network, if your device is connected to your network. Consider using a network control tool, like OpenDNS, which makes you an administrator of all traffic into your home network. You can block certain types of sites by category, such as porn or peer-to-peer file sharing (which can be quite dangerous). You also can use your computer’s own parental control content settings to avoid illicit sites.

Scan new devices

Frustrated by obstacles put up by savvy computer users, some criminals have taken to infecting USB flash drives. Plug it into your machine and whammo — they take control. Security researchers suggest that computer users migrate to online file-sharing using services such as Dropbox, Google Drive or OneDrive from Microsoft rather than hackable hardware, at least until manufacturers catch up and improve USB security.

Greg writes about personal finance, business and technology. His work has appeared in Businessweek, Newsweek, Forbes, Bankrate and a variety of trade ​publications.