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How do I determine what devices may be interferring with my Wifi?

0

All I'm trying to discover is if there are "other" devices in my home which are broadcasting my old SSID. I was told to dl Wireshark, which I did, and I'm scanning. How on earth do I find the information I'm looking for?

asked 02 Feb '16, 10:44

Diane%20Skellie's gravatar image

Diane Skellie
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accept rate: 0%

1

Share us a trace, tell us the SSID and we can help you... Otherwise you can search the SSID in the trace withh the following display filter:

wlan_mgt.ssid == "YOURSSID"
(02 Feb '16, 12:24) Christian_R

I'm sorry...I have no idea how to do this. But thank you.

(03 Feb '16, 08:24) Diane Skellie

2 Answers:

1

If you really mean "broadcasting", i.e. you want to locate a forgotten AP, I'd say you have to capture in monitoring mode and be lucky enough that your wireless adapter's driver indicates signal strength. So you would switch off the AP currently in use, let the wireless card in normal client mode show you the networks around you, and if you find one broadcasting the SSID, start capturing in monitoring (not "promiscuous") mode with display filter set to the SSID and move around the house while watching the signal strength information in the radiotap header of the received packets. The closer the number is to 0, the stronger is the received signal as the value is in -dBm (so e.g. -91 dBm is a weaker signal than -84 dBm).

Monitoring mode is only supported on Linux and Mac; to capture using Windows, you would currently need an AirPcap WiFi dongle. So maybe some WLAN monitor application on a smartphone may turn out to be a more appropriate tool for your task than Wireshark, while the principle would remain the same.

If you had something else in mind, come back and describe the situation and task more in detail.

There may be a number of other reasons why your WiFi is underperforming than a forgotten equipment using the same SSID.

answered 03 Feb '16, 01:44

sindy's gravatar image

sindy
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accept rate: 24%

My old router name (which was returned to TDS) still shows up as broadcasting a strong signal. My new router only shows a fair signal. I'm told other things can hold onto the signal (Wifi boosters?). I'm trying to find out if that's the case. I am not a computer professional and my knowledge is very limited. My internet company tells me I'm crazy, but searches on the web have shown me that my issue happens to others. Perhaps this forum is not where I should be looking for help.

(03 Feb '16, 08:23) Diane Skellie

I'm not a "computer person"

That sounds like a teacher's challenge. I don't think you're crazy, I think that several effects have combined together to give you a false impression of what really happens.

So if you feel like that, my e-mail address should be visible to you (as a logged in user of this site) and you may contact me directly. Some idea about what is your specialization might help me choose the right approach.

(03 Feb '16, 09:04) sindy

I am logged in, but when I click on your name, I do not see an email address. Can you see mine? If so, please email me. I'd really like to resolve this.

(03 Feb '16, 14:42) Diane Skellie

1

As @sindy suggested, there is some ambiguity regarding what you mean by "devices" and "broadcasting" in a WiFi network. Below is an explanation of the main devices within a WiFi network and how to capture them.

  1. Access Points/WiFi routers = these devices broadcast the SSID to the world (assuming that the AP/wireless router do not hide the SSID). To determine the available WiFi networks (i.e., what SSID's are being broadcasted) you do NOT need Wireshark. If you have an Android device, you can download a free app called WiFi Analyzer. This app provides a scan (both on the 2.4GHz and 5GHz) and shows the available networks. As sindy mentioned, you can walk around and then remain at a location for a few seconds and watch the signal level change. This gives a good indication where the AP's/wireless routers are located.
  2. WiFi clients = these devices do NOT broadcast an SSID, but can cause interference since they can be located on the same WiFi channel or co-channel. If the clients are connected to your WiFi network, then your AP/wireless routers should list the clients connected to your network. However, if the clients are not connected to your network, then you need a WiFi capturing tool (e.g., Wireshark). So as sindy explained, you would need: a) A linux/MAC machine b) WiFi adapter = preferably one that works on both 2.4GHz and 5GHz c) WiFi driver = one that can be put in monitor mode d) Wireshark Now you have all the ingredients. You can start capturing WiFi data. But how can you see all the clients? The best way is to have a script that will scan the interested channels and then analyze the data.

My recommendation = accept one of the answers to close this question. Then create a new question with more details using the information provided in this post.

answered 03 Feb '16, 07:08

Amato_C's gravatar image

Amato_C
1.1k●14●20●32
accept rate: 14%

I'm not a "computer person", just a wifi consumer who can't get a good signal from my new router because of the ghost of my old router. Thank you very much for your input, but I think this may be way beyond my understanding of the world!

(03 Feb '16, 08:26) Diane Skellie