How to Check If Someone Is Using Your Broadband Internet Router?

By Matthew Schieltz

The wireless router combined with your broadband modem provides the gateway you need to surf the Internet. Though you may share your WiFi network with friends and other trusted individuals, the possibility of outsiders tapping into your connection exists, and there are ways to check for this. Keeping your Internet gateway secure at all times with WiFi Protected Access (WPA) encryption built in to your router prevents these intruders from taking advantage of your WiFi network.

Things You'll Need

  • MAC addresses
  • Wireless router

Step 1

Obtain the MAC (media access control) addresses of all computers that are supposed to be on your network. In Windows operating systems, open the command prompt. Type "ipconfig /all." Find and write down the number next to the "physical address" listing. In Apple Mac operating systems, open System Preferences. Click the "View" menu and select "Network." Select your Internet connection and click "Advanced." Choose the "Ethernet" tab to find your MAC address under the title of "Ethernet ID."

Step 2

Go to your Internet router's configuration Web page. Type your router's IP address (your computer's default gateway) into the address bar of your Internet browser and press "Enter." Type the administration username and password to gain access to the router's configuration page.

Step 3

Look for the router's "DHCP" client table. Click the "status" section in the configuration Web page. This section often contains details of your network, such as the Internet router's firmware version details, the router's model number and details about your connection. Click the "Local Network" subsection. Click the "DHCP client table" section to open a new window or section.

Step 4

Compare the DHCP table details. Look at the number of "clients" or "host names" listed in the DHCP table. Compare the number of names on this list to the number of devices in your household or to those which you know are connected to your network. For example, if you have five computers and/or wireless devices connected to your network, then a maximum of five names should be listed in the DHCP table. Match the MAC addresses listed to those that you wrote down.

Step 5

Limit the maximum number of DHCP users on your network. Click the "Basic Setup" section in your router's configuration page. Locate the box indicating the maximum number of DHCP users allowed. Type the desired number in the box (e.g. type "2" if you only want to authorize two users). Save the changed settings. Limiting the number of DHCP users can prevent intruders.

Tips & Warnings

  • Find the default gateway in Microsoft operating systems by typing "ipconfig" in the command prompt and looking for the number next to the "default gateway" label.
  • Find the default gateway in Mac operating systems by opening the "Network" section from System Preferences. Click "Advanced" on the appropriate port (e.g. Wireless) and choose the "TCP/IP" tab; the default gateway number is the number next to the "Router" label.
  • Enable WiFi Protected Access (WPA) encryption through the wireless security settings on your router's configuration page. Keep the security settings on at all times.