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My machine is connected to a wireless router. Is it possible to analyse packets coming and going to the router? Can I use the bridged mode for achieving this? Actually I want the original packets coming to and going from the router(this may even include routing protocols) and not the NATed packets transmitted to the network.

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  • You do not say how are you connected, and what you intend to do with it, and to where are you and the router connected. If you are willing to do that, we can give you more interesting answers. Commented Nov 18, 2015 at 11:16
  • I am connected as a wireless client however I can connect using a LAN cable if necessary.
    – Sunny
    Commented Nov 18, 2015 at 15:19

2 Answers 2

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If you want to sniff the connections, and before the router does the NAT, you will have to do it at the ethernet side. There are is not a way to unNAT them on the wireless side.

To capture the traffic at the ethernet side, either you

1) connect both your PC and your wireless router to a switch that is able to do port mirroring (e.g. you mirror the port of the wireless router to the port where your PC is connected)

2) you put another ethernet card via usb in your PC, and configure linux as a router or better as a bridge for the traffic to traverse it

3) connect it to a switch with a network card with two IPs, and define it as a router to your wireless router (complicated setup).

After setting up one of this scenarios, you can use tcpdump, wireshark, or other related sniffing utils to listen to the connection.

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If you want to capture Frames in the router I would suggest you to use tcpdump regardless whether if it's a wireless or wired Connection, you will be able to capture it. man tcpdump this is a good start for you to know about tcpdump.

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  • The point about my comment is that we do not know wether he is connected by wifi or by ethernet to it, or if they are both in the same switch. We can assume is connected by wifi, however we are just assuming it. Commented Nov 18, 2015 at 13:58
  • Actually I want the original packets coming to the router, this may even contain packets of routing protocols. And I dont want to use wireshark or tcpdump directly as it will give me only the NATed packets
    – Sunny
    Commented Nov 18, 2015 at 15:02
  • It sounds to me that you have a wireless gateway, you're on the LAN side, and you want to capture packets on the WAN side. Is this correct? What type of device is it? If I'm correct, and this is just a typical home wifi gateway device, you'll have to set up a transparent filter between your wifi (WAN side) and your modem (or what have you), then on that filter, capture the packets (perhaps using tcpdump to a file, streamed to another box, or use wireshark live time)
    – stevieb
    Commented Nov 18, 2015 at 15:29
  • Sunny, please update the request about the NAT. Commented Nov 18, 2015 at 17:53

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