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How to Detect and Stop an Outside User from Stealing Your Wi-Fi

Arun Prabhu Oct 23, 2018
Getting a Wi-Fi connection is living wire-free. No more hassles, take your laptop anywhere within the Wi-Fi zone to sit and work or play. Unfortunately, all your wire-free enthusiasm can also be shared by someone not really invited to your party.
An outsider who knows how to get into your Wi-Fi can not only use it for himself, but he can also hack the data on your computer. This is very dangerous as your computer's security is compromised.
The hacker can be doing something illegal and the police would catch your IP instead. Detecting the user can be easy, but it is quite difficult to ascertain the identity, especially if all you have are the history records of his/her usage, and no addresses.
Once you know if your Wi-Fi is being leached, there are some steps that you can take to prevent it from happening again. The thing is, they connect to your Wi-Fi the same way as you do, so it pays to have some figurative walls around your Wi-Fi signals.

Basics of a Wi-Fi Connection

If you don't know much about the components (both hardware and software) in your Wi-Fi system, it would be good to know the basics of what they are, to work on them.
  • The signal for your broadband Internet connection is brought to your house through a cable or satellite modem, or a digital subscriber line (DSL).
  • The wireless router is attached to the modem, which transmits the signal through your house to give you the Wi-Fi connection in your house.
  • Your router will have a dynamic host client protocol (DCHP). DCHP tells router who is allowed to access the Wi-Fi connection and who isn't.
  • Every machine is given an IP address. The IP address tells the router who has accessed the Wi-Fi. The IP addresses are assigned to each computer with the help of a media access control address, or a MAC address.

Detecting an Internet Thief and Stopping the Thief

Detecting an Intruder

You know someone is stealing your Wi-Fi if:
  • Your network service is slower than usual.
  • Your network service keeps breaking down intermittently.
  • Your network speed is lowered at the same times everyday.
  • Your router is 'on' and 'blinking' even if your PC is off.
You can make sure whether your Internet service is accessed by an unknown user by doing the following things:
  • You can check your router logs. This changes from router to router; you can access the 'Help' section to figure out where the log is stored.
  • You can see any attached devices on the router admin page. You can access the page by typing your IP address in the browser (default gateway IP retrieval explained later).
  • Check out the MAC addresses of all the attached devices (MAC addresses are unique to all devices). If any of the addresses don't match the ones you already know, then it's an external unknown device.

Stopping the Intruder

Once you know that there's an unwelcome user, you can strengthen your defenses against them.
  • Since the router gives all connected devices an IP address, your main computer's IP address should be a default address like or . This is the default gateway IP address of your computer.
  • To find IP address, press Start → Type "Run" → Type "cmd" in the Run tab → Type "ipconfig" in the new window that opens. You'll get a list of things. Find the default gateway IP in there and note it down.
  • Once you get that address, type it in the browser, where you'll get to set the router address and password. If it's default, you don't need to put in the password every time you access it. Which means that if the setting is default, anyone can access your router to get free Internet (you pay the bill, after all).  
  • Again, the default address and passwords are different for different brands of routers. You can get the default values from the respective brand's site.
  • If you are using the defaults, change the address and passwords to something secure, something totally unique, long and which only you and your family can figure out. So every time someone logs in, they have to put in the password to access the Internet.
  • If you still feel you need more security, click on the "Wireless" tab in the router folder, go to "Security" and enable the WEP encryption. You'll have to give a WEP key for encryption. Be sure to note down this key before pressing "Accept". All your data is now encrypted using this key. 
  • The thing is, the person stealing your Internet probably knows a thing or two about hacking and will eventually find out the key too. You can also use WPA or WPA2 encryption, it's a little harder to hack into. It works the same as WEP and you'll need the key to decrypt the data.
  • You can get additional security through your firewall. Enable the MAC filter in the firewall setting. Add in all the MAC addresses of the computers that you want to be allowed to use the Internet, the firewall will ban the rest.
Note that all the steps mentioned are more for slowing down rather than stopping, depending on the skill of the unknown user. Also, since the range of your Wi-Fi is so small, you may also be able to see who is using the Internet.
If you're not really confident about messing with your computer settings, you can use a software like 'Who Is On My Wi-Fi' to find out who is using it. Once you figure out, you can successfully report the thief to the authorities.