Monday, December 7, 2009

Reader Question: Is Someone Jamming My WiFi?

I recently received the following email message from a reader:


I read some of the information you provided regarding Internet signals getting jammed intentionally and otherwise. Perhaps you can shed light on an issue. When our neighbors are NOT home, I can use a PC with wireless internet (set up in a room of my home facing their home) without ever getting knocked off the internet. When they ARE home, the signal repeatedly is lost. However, A laptop in another part of the home is rarely affected.

So I set up the laptop in the PC room and lost signals (when neighbor was home) on both machines (Provider rep. suggested I do this). Neighbor walks dog or otherwise is not on their property and there is no issue with signals. AND it is random. Usually neighbor comes in for lunch break and the Inet signal is lost.

Home from work and it is lost. I unplug wireless and it comes back. On and off. This is a new development (maybe two months. After the local police informed said neighbors to stop calling 911 to report bogus complaints on us, the signals began to drop. So we believe after police warned them to stop wasting 911 resources, they got a jammer and jam our signals at every opportunity to harass us. (Honestly, this is our first and hopefully last neighbor war. We don't know why they hate us so much but have been informed they hate everyone so we try not to feel too special.)

Question 1 - How can we test or otherwise determine the signals are being jammed (we are sure they are but need proof) and pin point the source? Prove or show great reason why the source is illegal.

Question 2 - How can we protect the signal from getting jammed?

Thanks for your insight.

I've written here in the past about the jamming of cell phone, GPS and Wi-Fi signals. Here's some ideas and possible answers to the reader's two questions.

Question 1 - How can we test or otherwise determine the signals are being jammed (we are sure they are but need proof) and pin point the source? Prove or show great reason why the source is illegal.

The best way to confirm someone is jamming is to use something called a spectrum analyzer. Wireless frequency spectrum analyzers are commonly used measure signals and interference. You could spend thousands of dollars on a full blown analyzer from a company like Agilent or use a 2.4 GHz USB spectrum analyzer from a company like MetaGeek. The company sells a 2.4 GHz analyzer for $99 that comes with software that will run on both PCs and Macs. According to MetaGeek, this analyzer will track all radio activity from any 2.4GHz device including WiFi, cordless phones, microwave ovens, Zigbee and Bluetooth. The software that comes with the device also graphically shows which channels to use and which ones to avoid. Here's more of when you would want to use a device like this from the MetaGeek website:
  • If you install, maintain, or troubleshoot access points, find the open channel and minimize the interference.
  • If you work with consumers, avoid a revisit by using a Wi-Spy in case they own a microwave or cordless phone.
  • If you experience WiFi interference on a regular basis, discover competing access points.
  • Conduct site surveys.
You could purchase one of these and, attached to your laptop running on battery, walk around your home looking for jamming/interference signals. If you want to get up unto the higher frequencies where the 802.11n devices have the option of operating (802.11n can use both 2.4 GHz and 5 GHz frequencies.), it will cost you quite a bit more money to measure interference. MetaGeek sells something called the Wi-Spy DBx, a 5GHz analyzer, for $599 that also comes with software.

You may also want to first try KisMac or iStumbler on an Apple machine or NetStumbler on a PC. These applications run on the computer and give you access point information including channels being used. Sometimes just swapping a channel can fix interference problems. For example, if your neighbor is using channel 6 you may want to change your access point to use channel 11.

Question 2 - How can we protect the signal from getting jammed?

If your neighbors are jamming your signal with a well designed jamming device, determining and using an open channel on your wireless access point won't work. If the jamming has been going on for a while chances are the jammer they are using functions only at 2.4 GHz. I'm I think the best thing to try (if you are currently running a 802.11g network) initially would be to switch over to an 802.11n access point and upgrade to 802.11n on your computers. If you have newer computers that may have 802.11n support built in.

You could run the 802.11n network at the higher 5GHz frequency which would be immune to the lower 2.4GHz jamming signals. This would be an inexpensive attempt that would also give you the bonus of much better network bandwidth and immunity from other interference sources (e.g some cordless phones, microwave ovens, etc) in you home.

I'm looking forward to hearing if this works.


Divahdiva said...

Thank you so much. We are on it and will post the results.

Unknown said...

Thank you. My neighbours are jamming my Ring doorbell, and I'm in the process of contacting the police. I'll try all the things you've mentioned, but my neighbour is extremely crafty it's having an affect on my mental health.

Kiki_Park17 said...

I’m having a similar problem with my neighbors. They have been on my property since I put up cameras to test them in different ways. I did change the channel and things improve briefly. My neighbors have unlimited resources where I am taking care of my dying mother and neither of us have the money to buy a more advanced security system. I have some blink cameras but if the wifi is bad they are useless. He knows how to look for infra red cameras (I’ve learned to as well) however their system would see me if I touched their property. I have an app called Fing that
assesses my current wifi speed. Despite paying for the best wifi speed at one point yesterday it was at %30!
I’ll call ATT but I just know he’s doing it. They have a huge infra red camera that points into our yard. One of my blink cameras seems to set it off. I’m no longer scared but I want to catch him. Right now I’m having trouble just getting these crappy things to work.
I have also tried using Alfred with an old iPhone but the sensor doesn’t work behind glass and I’m not sure I want to risk putting it outside, for obvious reasons.
The police do believe he smashed my patio table and was in my yard doing things to scare me. Now I believe the harassment is turning into some kind of digital interference (and I’m worried he’s hired a hacker because yes, he would go on the dark net). Now I’m noticing main or packages missing. We never received mom’s pension check which is delivered by mail and arrives within 1-2 days of scheduled payments. I don’t have a camera on the front but it wouldn’t work to catch him, only deter him which is good. However what he has done this past year to terrorize me is unacceptable and I need to catch him. My father died last November, my mom was supposed to but she’s still alive though bed ridden. I don’t tell her about all of this but some. I have to tell her if I’m going to spend a couple hundred dollars and what on. We’ve never needed cameras. We were robbed about 23 years ago. My dad reinforced doors, windows and got another dog.
This person and his wife are horrible people. Once I got a ride from a woman in our neighborhood and she said he has hit on every woman in their neighborhood social group. He had to apologize because her husband made him. My mother and I are vulnerable sitting ducks. I need to find a way to catch
him. I know how to trigger him but I need to equipment to catch it. I wouldn’t do anything illegal. His most recent antics began after he had a fence installed and the fence company left a huge railroad tie? in our yard. They are so heavy and I have no way to dispose of it. When a strong person came for a visit we pushed it over the fence. The next night my table was smashed and there was 2 weeks of little stuff to scare me.
An advice would be of help. I can’t find any group on Reddit that might be able to help me with answers to my questions.

Gordon F Snyder Jr said...

Can you wire up and not use WiFi in the house? Wired Ethernet cameras are available and you could use one of those to monitor packages.

Anonymous said...

File a complaint with the FCC as well.