Is Someone Stealing Your WiFi?

Category: Wireless

Is your wireless Internet connection sometimes mysteriously slow? It's possible that you're sharing it with a stranger. But how can you know for sure if a neighbor or a malicious hacker has tapped into your wifi? Read on to learn how you can detect bandwidth bandits, and give them the boot...

The Rankin File

How to Detect and Defeat Wifi Intruders

There are many possible reasons why your wireless Internet connection suddenly slows to a crawl. An unauthorized user stealing your bandwidth is one of them. It is unlikely that such a bandwidth thief will access your WiFi network if you have implemented the basic WiFi security described in my article, Wireless Network Security Checklist. But it’s certainly a possibility that should be checked. Anyone with the skills and determination to hack your secured network is probably up to some sort of criminal activity.

There are many casual, even “innocent” bandwidth thieves who see an available network and just assume it’s OK to “borrow” it. If they are challenged for a password when they attempt to log on, they'll probably just give up and move on to another target. If you haven't bothered to assign a wifi access password, the front door to your network is wide open. If you're not sure why that's a bad idea, see The WiFi Security Mistake You Must Avoid.

Wifi Hacking

A real cybercriminal is another matter. He is out to steal something of value from you or others. He may peruse computers on your network for identity and financial information he can use or sell. He may use your Internet connection to download files illegally or hack other networks, setting you up as the fall guy when the crime is traced back to your router. This sort of crook has the tools and skills needed to defeat most WiFi security measures, especially if you have a weak password.

Windows and Apple computers have built-in utilities that show what devices are connected to your network. You can use these tools to look for unknown computers that should not be connecting to your network. Obviously, the first step is to know what devices are authorized. Each authorized computer should be assigned a computer name that you can recognize easily, i.e., "Jane PC" or "Billy Laptop". Other devices, such as printers, will have built-in names such as “HP Model 8600.” You should be familiar with what you own.

Detecting Unwanted Wifi Connections

In Windows 7, click the Start button and type “network” in the search box. Click on the word “Network” which should be the first item in the search results. A multi-part display of connected devices will appear, listing computers, media devices, network infrastructure, and other items connected to your local network. “Computers” will include PCs, smartphones, and tablets. “Media devices” include printers, gaming consoles, smart TVs, and the like. “Network infrastructure” includes your Internet router and/or modem. "Other Devices" will include streaming video players, such as a Roku box.

For some reason, connected iPods, tablets and smartphones do not show up here. An unauthorized device will probably be among the “computers” listed, but if (for example) you see an Xbox that doesn’t belong to you, you obviously have an interloper. Apple OS X computers have a similar utility. You can access it via Finder > Go > Network.

Your router’s configuration program provides a better view of ALL devices connected to your network. By logging into your router, you can see a list of devices that currently have IP addresses assigned to them. Consult your router’s documentation (or Google it) to learn how to access this list. Devices that may appear in this list include desktop and laptop computers, tablets and ebook readers, iPods, smartphones, wireless printers, streaming devices such as Roku or AppleTV, gaming consoles, and television set-top boxes. Many routers also store logs of past connections, which you can peruse to see what devices connected when you weren’t looking. If you don't know how to login to your router, or you don't know the password, ask your Internet Service Provider for help.

If you discover an unauthorized user on a secured WiFi network, my advice would be to immediately change BOTH your router login password and your wifi access password (see my Wireless Network Security Checklist link above) and then restart your router. If the intruder re-appears, it’s time to contact your Internet Service Provider, or maybe even call the cops.

Real-Time Wifi Monitoring

None of the utilities described so far alerts you when an unauthorized device connects to your network. A nifty third-party Windows utility called WhoIsOnMyWiFi does. Running in the system tray, it checks your router’s network connections list at intervals that you can set, typically every two minutes. Audible and popup alerts tell you when an “unknown computer (is) found.” You can mark a device “known” and it won’t trigger an alert again. The program comes with a 30-day free trial. For $34.95, you get unlimited use, updates, and the ability to selectively “block” devices that try to connect to your network even if they provide the correct password.

However, it’s important to understand what this “blocking” really does. The “blocking” feature is really more of a “jamming” feature. From what I can tell, it's similar to a denial of service attack, but you become the "attacker," flooding the intruding computer's network. It does not stop an intruder from connecting to your router, but it does prevent them from accessing the Internet and any devices on your network.

My intuition tells me this would necessarily have some impact on the speed of your wireless network. Perhaps a better idea, if an intruder is detected, would be to change your router's wifi access password, then restart the router. That would boot the intruder from your network entirely, without continuously draining network resources.

Your thoughts on this topic are welcome! Post your comment or question below...

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Most recent comments on "Is Someone Stealing Your WiFi?"

Posted by:

22 Jul 2014

What about MAC address filtering?

What about a router that allows visitors to access the WiFi, but with limited rights, such as not being able to see the other PCs in the network?

Posted by:

22 Jul 2014

I called the company mentioned, and they do, in deed, us a DOS (denial of Service) attack to keep the computer off line. (paraphrased) 'We send them very large packets of mealiness data every few second using the host machine until the machine logs off the network." They continued, "This is generally enough to discourage a machine from continually logging back on . . . . but for a persistent machine we have a (device) that hooks to your router, recognizes the fingerprint of the machine and keeps it from longing on, but that is more expensive than our basic software solution . . . . For information that should remain very secure (eg between my University and my main [disconnected from the web until transmission time] machine, we recommend that you change all your pass words for all your machines at every level, from sign-in to log-in and that you follow Very Best Practices (what you have preached) when you do this, don't take short-cuts." ....... "For home LANS of just a few (under 10 or so devices) (most), . . . people who don't wish or don't know how to change their passwords, we recommend our software because the $40-$50 package you chose is often well worth the hours of frustration and typos we all make that drive even professionals crazy....."

So, you were correct, they do use a DOS attack approach which WILL slow your machine down until whoever it is (with me a roommate who moved out) logs out. My bet is if your Ex knew you had one of these, she'd just leave her lap-top logged into your network while she was shopping leaving you at a dial-up speed for HOURS.

And for the bad-boys who read what the good guys are up to, they do log ALL entries so you can't buy one and use your neighbors ISP to disrupt their LAN, the door the cops will knock on will be yours, not theirs (UPPER end package).

Posted by:

22 Jul 2014

A quick and simple overview Bob. Just checked and all is fine. Thanks ;-)

Posted by:

22 Jul 2014

Nice article for computer geeks. All the things you suggest are great ideas, but I am no computer genius. Change the router password? Yes? And if I screw it up I am locked out of my own network. Security is No.1, but way too complicated unless one has hours and hours of spare time.

Posted by:

23 Jul 2014

And what about disconecting the wifi? Is it still in danger? Mine is disconected.

Posted by:

23 Jul 2014

Really great article and very useful info. Did not find anything unusual, but, it was a great reminder to be alert.
Changing the password is not a complicated procedure, but, it can save your system and is a lot more easy than taking the computer in to have it repaired or to redo your hard drive.
Thanks again for the article. EXCELLENT !!

Posted by:

23 Jul 2014

Boy, after I found out that someone was "stealing" my Wi-Fi Broadband connection, I learned my lesson. This happened about 4 years or so ago. I learned to have a better password, than the DSL's unit serial number, that was recommended by AT&T.

I don't remember if, I found this program, from reading one of the articles by Bob or that I found while looking for something else or I saw this program "listed" at a download website. I only know, that it intrigued me and I wanted to try it out, for myself.

Wi_Fi Guard is a small, FREE program for Windows & Linux, but, there is a $9.99 charge for a Mac ... It monitors my Wi-Fi and lets me know, when anything connects to my Wi-Fi. I have been using this program, for about 9 months or so and have found it, to really work! Believe me, when I say that it is small and takes practically no resources, I mean it. Here's what it can do, for FREE, if, you are using Windows or Linux:

Key Features:

1)Pings computers and other network devices and displays those alive.

2)Detects firewalled computers that do not respond to ping.

3)Scans your network at a specified interval.
Immediately alerts you if an unknown device is found.

Runs on Windows, Mac OS X and Linux.
Free for Windows & Linux, only $9.99 for Mac OS.

Here is the website, to check it out for yourselves.

Posted by:

26 Jul 2014

Very interesting article, thank you. Slow running here in Europe can be the ISP throttling your connection, usually in response to heavy traffic on your router - they deny it but it happens, best thing then is to challenge the ISP and magically things improve.
We also have a great system with some ISPs, BT in the UK, Orange and SFR in France. Every router emits two signals, one your personal WAP/WEP encoded, the other is a "public" signal which can be accessed by anyone with their own ISP ID and password - not secure but awfully useful when travelling. I don't know if these will show up using your techniques to view other users.
You can see folks sitting on public benches wherever there is a router in range, working away on pads, laptops etc. I haven't noticed any reduction in speed when people have been working outside my house.

Posted by:

04 Nov 2015

Bought new all in one computer. Went to set up office 365, rec'd message that verification was needed. Called number on back of card. Talked with Sam who told me I had a worm virus in my new computer because of my wireless connection. Some setting was not on. Trying to sell me a protection plan for $200/1 yr, $350/3 yrs, or $500/ lifetime. Scam or what?? I asked if he worked for Microsoft, he basically said he did but was independent. Who do I trust to fix my computer? I follow most of what I've read, but don't feel I can complete the task.

EDITOR'S NOTE: Almost certainly a scam. What number did you call?

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Article information: AskBobRankin -- Is Someone Stealing Your WiFi? (Posted: 22 Jul 2014)
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