How to Tell If an Outside User Is on Your Wireless Network

POSTED AUGUST 2012

Wireless security is very important these days. You don't want anyone stealing your bandwidth or getting into your network to perform malicious attacks on your computer. This is a guide to help you know when someone else is on your wireless network. Since every wireless router is different, this article will discuss the basics and use one of the most popular wireless routers, the Linksys WAP54G as an example. The steps for your router may differ. This guide assumes you are connected to your router (either through a network cable or over its wireless signal) using DHCP correctly.

Steps

1. Open your web browser and input your default gateway's IP address. To find this:
   
   
   
   
   
   • Go to Start > run, and type cmd
   • Type ipconfig and press enter. It will list the default gateway here. Once you have your default gateway address, open your web browser and type it in the URL bar.
2. Input your router's username and password.
   
   
   
   • Default for Linksys products is usually username: (blank) password: admin
   • Default for Netgear routers is Username: admin password: password
   • Default for Dlink routers is Username: Admin; Password: (blank).
   • Default for Siemens routers is Username: Admin; Password: admin (all lowercase).
   • Default User Names and Passwords can be found sometimes under the router, on the label or using Google.
   • If you are having trouble finding the UN and PW then try http://www.portforward.com this website is usually used for opening ports for P2P programs and games,but when it shows you how to open your ports it tells you the default UN and PW for the router. The router list is HUGE.
3. If you are using the default username and password, go to the Administration tab to change it to something more secure. From the Router's user interface you will probably have a setting to log Users going through the router--enable it if not already.
   
   
   
4. Get a pen and paper, and use the steps shown above finding the default gateway to find your MAC or also called physical address of all computers/devices that use wifi/wireless in your home or that will be using it and write them down. From time to time check the log to see if any unknown addresses show up. If so, then someone is leeching off your internet. MAC/physical addresses are unique hexadecimal code that identifies each Network card inside every PC that uses Ethernet. No two MAC addresses are the same.
   
   
   

Finding who is on your network

1. Navigate to the Setup tab.
   
   
   
2. Scroll down until you see 'DHCP Server' if it is enabled, continue to the next step. If it isn't enabled, enable it.
   
   
   
3. Click on the "Status" tab and then on "Local Network" just below the main tabs.
   
   
    
   
   
    
4. Click the button that says "DHCP Clients Table". This list will tell you the computer name of everyone connected to your network on DHCP (DHCP automatically configures a computer's IP and DNS settings. This only works if everyone connected uses DHCP. If someone connects and uses their own static address, then this will not show them.)
   
   
   

Other Ways to Find who is on your network

1. Download and Install Who Is On My Wireless
   
   
   
2. Click the Scan Now button and it shows all computers on the network.
   
   
   

 Tips

• If you are concerned about people connected to your network, click the Wireless tab then click on Security and enable WPA or WPA2. Everyone that wants to connect will need the WPA or WPA2 key to connect. Do not use WEP. WEP encryption is so weak that it can be broken in less than a minute.
• If you want to deal with assigning your own IP address, disable the DHCP server on your router. You will have to assign your own internal IP address, but it will keep some people out that do not know your subnet (or how to do it)
• Use a different subnet. This will keep people guessing if your DHCP server is off. To do this, just change the router's IP address (on the Setup page) to something other than default (192.168.1.1). Try 192.168.0.1.
• Installing a firewall will HELP prevent cracking of your computer
• Enable MAC address filtering. Only allow MAC addresses of computers you know. While this is a good option for cursory protection, MAC addresses are broadcast between your computer and your wireless router in clear text. A would-be attacker can use a packet sniffer to see your MAC address and then use a MAC address spoofer to fool your router.
• Once you're connected to your network, disable the broadcast option. This will stop the router from broadcasting its name. You will still be able to connect, since you know the name.
• Beware that everything mentioned here, except enabling WPA/WPA2 encryption, does not prevent people from connecting to your network. It just makes it a little harder for the inexperienced user.