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I am connected to my home router using wifi on my laptop. My ip is 192.168.0.107 but on wireshark I am seeing traffic from 192.168.0.106, which happens to be my smartphone. I was expecting to see only traffic to and from my computer though. I am running windows 8.1. I would like to know why I am seeing these packets which are shown in the picture here

2 Answers 2

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These are multicast packets, in particular Simple Service Discovery Protocol (SSDP) and Multicast Domain Name Service (MDNS) packets that are used for configurationless discovery in one single LAN or WLAN segment.

Your home router broadcasts these to all devices, including your PC.

So it's perfectly normal that you see those, this is as it should be.

Edit

So the other part of the question is "why don't I see traffic from other devices". You are actually not seeing any other traffic from your Smartphone, either (except the multicast). That's because unicast packets (with a destination address of a single IP device, e.g., 192.168.0.x, instead of a multicast address, e.g. 224.0.0.x) are not broadcast by your router to all other WLAN devices. Which makes a lot of sense, because due to the encruption, it would have to be resent separately to all the n other devices, taking up n+1 airtime. But since the destination address says "these devices are not interested in the packet in the first place", it doesn't. OTOH, the multicast packets are meant to be sent to every device on the network.

So if this is an XY question and your real question is "how do I sniff packets from some other device via WLAN", the answer to that is: You have to become the access point for that device.

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  • but the thing is there are lot of other devices on the LAN too. But I'm not seeing any traffic from other devices except the smartphone.
    – Non-named
    Commented Dec 12, 2017 at 2:40
  • You become the AP or you run in promiscuous mode. Commented Dec 12, 2017 at 9:26
  • @djsmiley2k: Wireshark already put the interface in promiscious mode. If the WLAN router isn't copying packets between the Smartphone and some destination to your PC, having the interface on the PC in promiscious mode doesn't help at all.
    – dirkt
    Commented Dec 12, 2017 at 10:26
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WireShark logs all the network traffic it sees. In particular, on a WiFi network, WireShark will see all other traffic on the same WiFi network.

To see traffic to and from your laptop only, you will need to use a filter, similar to the one you defined, but using your laptop's IP address:

ip.src == 192.168.0.107 || ip.dst == 192.168.0.107

This is the way WireShark is intended to work, so that you can use a PC to monitor other devices, such as WebCams, printers, TVs, sound systems, etc, which cannot be used to run WireShark themselves.

I have tested this on Ubuntu with a Laptop which uses a Broadcom WiFi chip-set, and absolutely confirm that WireShark behaves in this manner. This is why I added my answer, because I was seeing buffers which were not explained by @dirkt's answer (which completely answers the buffers logged in the question), and I assumed that the questioner would come across these in future logs.

I was puzzled by my down-vote, so I asked a friend to run similar checks and he got different results on Windows with an Intel chip-set. I was surprised that the same software would behave differently on a different OS, but he suggested that maybe Windows stops the interface running in promiscuous mode.

I don't mind being down-voted if I get something wrong, but I would like to be told what is wrong so that I can correct it. We wouldn't accept a question that says "something's wrong - please help", and I don't see why down-votes should be regarded differently.

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