How to Detect and Remove Unauthorized Devices from Your Network

Finding an unknown device on your home network can be alarming. It could be a forgotten device you own, a neighbor who guessed your WiFi password, or worst case, an attacker who has gained access to your network. Knowing how to identify all devices on your network and remove unauthorized ones is a critical skill for maintaining network security.

Why Unknown Devices Are a Concern

An unauthorized device on your network can be used for several malicious purposes. The person could be stealing your bandwidth, slowing down your internet for everyone else. They could be intercepting your network traffic using man-in-the-middle techniques, capturing passwords and sensitive data. They might use your network for illegal activities, which could be traced back to your IP address.

Even seemingly harmless bandwidth theft is a security concern because the unauthorized user is inside your network perimeter, with potential access to shared files, printers, and other network resources.

Checking Your Router Device List

The first step is to log into your router administration panel and check the list of connected devices. This list typically shows the device name, IP address, and MAC address for each connected device. Some routers also show the connection type (wired or wireless) and how long the device has been connected.

Go through the list and identify every device. This can be challenging because device names are not always descriptive. A device might show up as a string of characters rather than a recognizable name. Cross-reference MAC addresses with your known devices to help identify them. Many router interfaces now show the manufacturer based on the MAC address prefix, which can help you identify device types.

Using Network Scanning Tools

For a more detailed view of your network, use a network scanning tool like Fing, Angry IP Scanner, or Nmap. These tools scan your network and provide additional details about each device, including open ports, operating system information, and service information. This extra detail can help you identify mysterious devices.

Fing is particularly user-friendly and available as a mobile app. It identifies devices by manufacturer and type, making it easy to distinguish between your Samsung TV, Apple iPhone, and Google Home device. The app also maintains a history of devices that have connected to your network, so you can see if unfamiliar devices connected in the past.

Identifying Mystery Devices

When you find an unrecognizable device, do not panic. First, check if it might be a device you forgot about. Common culprits include smart plugs, WiFi-enabled kitchen appliances, e-readers, older phones or tablets, and streaming sticks. Ask other household members if they connected any new devices recently.

Look up the MAC address manufacturer prefix. The first six characters of a MAC address identify the manufacturer. You can search this online to determine the device brand. If the manufacturer matches a device you own, that narrows down the identification.

Removing Unauthorized Devices

If you have identified a device that should not be on your network, the most effective response is to change your WiFi password. This immediately disconnects all devices, and only those with the new password can reconnect. While this means you need to reconnect all your legitimate devices, it guarantees that the unauthorized device is removed.

For a targeted approach, some routers allow you to block specific MAC addresses. This prevents the device from reconnecting without changing the password for everyone else. However, MAC addresses can be spoofed, so this is not foolproof.

Preventing Future Unauthorized Access

After removing unauthorized devices, take steps to prevent future intrusions. Use WPA3 or WPA2-AES encryption with a strong password. Disable WPS, which can be exploited to gain network access. Consider enabling MAC address filtering as an additional layer, though remember that this alone is not sufficient since MAC addresses can be faked.

Enable notifications for new device connections if your router or network monitoring app supports this feature. This way, you will be alerted immediately whenever a new device joins your network.

Regular Network Audits

Make it a habit to review your connected device list at least once a month. A regular audit helps you catch unauthorized devices quickly and also helps you maintain awareness of what is on your network. Remove any devices you no longer use, and update the list of recognized devices whenever you add new hardware.

Consider maintaining a written inventory of all devices on your network, including their MAC addresses and IP assignments. This makes future audits much faster because you have a definitive list to compare against.

Conclusion

Detecting and removing unauthorized devices from your network is an important part of maintaining security. By regularly monitoring your connected devices, using network scanning tools, and following up with strong preventive measures, you can ensure that only trusted devices have access to your home network.