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how to capture traffic of all devices that connected to a broadband modem with wireshark? or how to capture a adsl broadband modem?

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asked 02 Dec '15, 03:38

kj_saeid's gravatar image

accept rate: 0%

If the devices are connected to the broadband modem using Ethernet ports of the modem, try to use these instructions. It is very likely that you will need additional hardware, unless your modem is running OpenWrt or some similar linux-based firmware allowing you to run tcpdump directly on it.

If some questions still remain after reading the instructions, come back here and press "add a comment" to this answer to enter your additional questions.

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answered 02 Dec '15, 05:28

sindy's gravatar image

accept rate: 24%

thans for your answer, but please see this picture's link and answer how to capture traffic between wireless modem and ISP and between client and wireless modem with system that wireshark installed on?

thank you

(03 Dec '15, 03:01) kj_saeid

First of all, "wireless something" can be quite confusing.

A "wireless access point" normally describes an equipment to which "wireless clients" talk using IEEE 802.11 family of protocols, popularly known as "WiFi".

On the contrary, a "wireless modem" typically means an equipment which allows to connect your PC to the internet using a public mobile network and its air interface (the 2G/3G/4G, EDGE, HSPA, LTE etc. acronyms are relevant here).

Your picture suggests that when using the term "wireless", you are talking solely about WiFi and do not have in mind the 2G/3G/4G mobile network.

Supposing this is true, you can use a WiFi card capable of "monitoring mode" to analyse communication between the PCs and the access point. Everything what could ever be said about the subject has already been said here.

When it comes to capturing the communication between the ISP and your box in the middle of your picture, it becomes much harder. Basically, no interfaces capable of receiving the signal which is used on the cable towards the ISP are available at an ordinary PC (regardless whether it is a "cable modem", which is a name usually used for modems connected to coaxial network used for Cable TV distribution, or an "xDSL modem", which is a name usually used for modems connected to twisted pair network used for telephony service). So if your cable modem and your WiFi access point are actually two separate boxes, you could capture on the Ethernet cable connecting them, using the methods described in the link in my initial answer. If it is an "all-in-one" box, you may still be able to capture "almost at the cable" if the box can be flashed with OpenWrt. Or replacement of the all-in-one box with two separate ones may be an option.

And if you really feel brave, you may try the GNU radio project to connect to the cable and demodulate and decode the signal running there. But such approach requires a specific hardware (typically, a USB TV tuner) and basic skills in electronics allowing you to connect this hardware in parallel to the cable.

(03 Dec '15, 05:36) sindy

thank you very much :))

(03 Dec '15, 08:34) kj_saeid
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question asked: 02 Dec '15, 03:38

question was seen: 3,265 times

last updated: 03 Dec '15, 08:34

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